The present of nuclear cardiology: a great past opens the way to a bright future.
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Cardiology↗
Biomedical subjects
R Sciagrà
Publications and source records attributed to R Sciagrà.
Gated single-photon emission computed tomography. The present-day ''one-stop-shop'' for cardiac imaging.
UNLABELLED: Gated single-photon emission computed tomography (SPECT) is the current state-of-the-art approach to myocardial perfusion imaging. Initially, major emphasis was given to the improvement in diagnostic accuracy of myocardial perfusion imaging for the detection of coronary artery disease, because the evaluation of wall motion and thickening allows the recognition of attenuation artifacts and increases the observer's confidence. Different processing algorithms make possible to perform a reproducible and reliable assessment of left ventricular (LV) function, which has been extensively validated against various reference METHODS: Several articles report the additional value of functional data derived from gated SPECT to increase the accuracy of myocardial perfusion imaging in particular patient groups, such as women, to enhance the detection of multivessel coronary artery disease, and to permit the recognition of severe stenosis. An extensive literature indicates that gated SPECT allows a more accurate and reliable prognostic stratification of patients with known coronary artery disease. More recently, the peculiar contribution of gated SPECT in the assessment of myocardial viability has been demonstrated, with the possibility to evaluate in a single myocardial perfusion study the presence of preserved tracer uptake and the amount of contractile reserve through the acquisition of gated SPECT during inotropic stimulation with dobutamine. The most recent advance in the application of gated SPECT is the use of this technique for the reproducible assessment of LV functional changes, at follow-up or during inotropic stimulation, with perfusion data in the background. Various clinical settings, such as assessment of response to medical or resynchronization therapy in dilated or ischemic cardiomyopathy, prediction of outcome in chronic coronary artery disease with LV remodeling, evaluation of different treatment strategies in acute myocardial infarction, could take advantage from the unique combination of perfusion and functional data made possible by the use of gated SPECT. In conclusion, myocardial perfusion imaging with gated SPECT is a convincing reality in the field of cardiac imaging and has a still largely unexplored potential for a wider use in heart disease.
Coronary Artery Disease↗
Classification of ischemic dysfunctional myocardium combining perfusion quantification and contractile reserve evaluation using nitrate-enhanced gated single photon emission computed tomography with dobutamine test.
AIM: In patients with ischemic cardiomyopathy, the differentiation of dysfunctional myocardium in scarred versus hibernating is oversimplified. We evaluated a more complex classification using an imaging technique currently employed for viability detection, having as reference the postrevascularization outcome of dysfunctional segments. METHODS: In 35 patients, we performed gated single-photon emission computed tomography (SPECT) (resting and nitrate-enhanced study, the latter with baseline and dobutamine acquisition) before revascularization. The outcome after revascularization was assessed by repeating resting gated SPECT. Dysfunctional segments without functional recovery in postrevascularization gated SPECT were defined scar (either nontransmural or transmural according to tracer activity); those with recovery were divided in stunned (unchanged uptake) or hibernating (improved postrevascularization activity). This reference classification was compared with the categorization based on prerevascularization gated SPECT. RESULTS: Contractile reserve in dobutamine gated SPECT differentiated scarred from viable segments with 78% accuracy. Tracer activity in nitrate imaging distinguished the degree of transmurality. Nitrate-induced activity increase was significantly higher (p<0.0001) in the hibernating segments (14.9+/-20.4%) than in transmural (4.8+/-13.4%) nontransmural scars (3.3+/-13%), or stunned segments (2.2+/-8%). The presence or absence of nitrate-induced activity increase predicted the postrevascularization perfusion changes in viable myocardium and differentiated hibernating from stunned segments. The prerevascularization classification showed a good agreement with the reference categorization (kappa=0.50). Conclusion. Combining contractile reserve evaluation and perfusion quantification within a single study with baseline-nitrate gated SPECT and dobutamine test it is possible to achieve a comprehensive classification of dysfunctional segments.
Adult↗
Prediction of functional recovery in patients with chronic coronary artery disease and left ventricular dysfunction combining the evaluation of myocardial perfusion and of contractile reserve using nitrate-enhanced technetium-99m sestamibi gated single-photon emission computed tomography and dobutamine stress.
This study aimed to assess whether contractile reserve evaluation using dobutamine gated single-photon emission computed tomography (SPECT) improves the capability of quantitative perfusion analysis to predict functional recovery of viable hibernating myocardium. Resting and dobutamine nitrate-enhanced technetium-99m sestamibi (sestamibi) gated SPECT studies were performed in patients with coronary artery disease who had left ventricular dysfunction. Tracer activity was quantified, and wall motion and thickening visually scored. Reversible dysfunction was identified with gated SPECT repeated after coronary revascularization. Using the best activity threshold, perfusion quantification achieved 85% sensitivity and 55% specificity. Contractile reserve detection was significantly less sensitive (64%, p <0.0005), but more specific (88%, p <0.00001) than perfusion quantification. However, in the subgroup of hypokinetic segments, the sensitivity of contractile reserve assessment was just slightly lower than perfusion quantification (72% vs 91%, p = NS), whereas specificity was significantly higher (94% vs 23%, p <0.00001). Conversely, in the adyskinetic segments, perfusion quantification was significantly more sensitive than contractile reserve (82% vs 59%, p <0.005), but similarly specific (76% vs 85%, p = NS). Therefore, the identification of reversible dysfunction based on perfusion quantification in adyskinetic segments and on contractile reserve detection in hypokinetic segments was significantly more specific (83% vs 55%, p <0.00001) than standard quantitative perfusion SPECT, without major loss in sensitivity (78% vs 85%, p = NS). In conclusion, contractile reserve evaluation using dobutamine gated SPECT enhances the reliability of nitrate-enhanced sestamibi SPECT when used to predict reversible dysfunction in hypokinetic segments, whereas perfusion quantification remains superior in adyskinetic segments.
Aged↗
Technetium-99m sestamibi imaging to predict left ventricular ejection fraction outcome after revascularisation in patients with chronic coronary artery disease and left ventricular dysfunction: comparison between baseline and nitrate-enhanced imaging.
Acceptance of technetium-99m sestamibi as a tracer of myocardial viability is growing, particularly when nitrate-enhanced imaging is used. However, few data are available on the ability of 99mTc-sestamibi to predict the evolution of global left ventricular ejection fraction (EF). The aim of this study was to examine the ability of resting and nitrate 99mTc-sestamibi single-photon emission tomography (SPET) to predict EF changes after revascularisation in patients who have chronic coronary artery disease with left ventricular dysfunction. Using baseline resting and nitrate 99mTc-sestamibi SPET, we studied 61 patients scheduled for revascularisation because of left ventricular dysfunction. EF was estimated using two-dimensional echocardiography before and after the intervention. A post-revascularisation improvement of > or =5 EF units was defined as significant. Using a 13-segment model, 99mTc-sestamibi activity was quantified and the nitrate-induced activity changes calculated. Three different criteria for detecting viability (defined as post-revascularisation reversible dysfunction) in asynergic segments were compared: (1) resting 99mTc-sestamibi activity > or =60%; (2) nitrate 99mTc-sestamibi activity > or =65%; and (3) nitrate-induced increase >+10% or nitrate-induced increase < or =+10% and nitrate activity > or =65%. EF increased significantly in 32 patients. The number of viable asynergic segments was significantly higher in these patients than in the remaining 29 subjects, and the difference was greater (P<0.0002) using definition (3) than using either baseline (P<0.002) or nitrate activity (P<0.0005). There was a significant relationship between EF changes and number of viable asynergic segments: Spearman R=0.38, P<0.005 using baseline; Spearman R=0.39, P<0.002 using nitrate activity; and Spearman R=0.55, P<0.000005 using definition (3). According to receiver operating characteristic (ROC) curve analysis, this last criterion achieved the best results (81% sensitivity, 69% specificity and 75% accuracy), with an area under the ROC curve of 0.838; this area was significantly larger than when using either baseline (0.744, P<0.02) or nitrate activity (0.747, P<0.005). 99mTc-sestamibi SPET appears able to predict the evolution of global left ventricular EF after revascularisation, thereby confirming the value of 99mTc-sestamibi as a tracer of myocardial viability. The combination of baseline resting and nitrate imaging seems to significantly improve the diagnostic accuracy of 99mTc-sestamibi SPET for this particular purpose.
Adult↗
Comparison of baseline and low-dose dobutamine technetium-99m sestamibi scintigraphy with low-dose dobutamine echocardiography for predicting functional recovery after revascularization.
Injection of sestamibi during low-dose dobutamine (LDD) infusion might improve tracer ability to detect viable myocardium. This study investigated the potential value of LDD technetium-99m sestamibi (sestamibi) single-photon emission computed tomography (SPECT) in predicting functional recovery after revascularization by comparing its results with those of sestamibi SPECT at rest and of LDD echocardiography. Before revascularization, 23 patients with chronic coronary artery disease and regional left ventricular dysfunction underwent sestamibi SPECT at rest and, on a separate day, LDD echocardiography and sestamibi SPECT with tracer injection during LDD infusion. Echocardiography at rest was repeated after revascularization. Semiquantitative sestamibi uptake results (grading from 0 = normal to 4 = absent) and wall motion (grading from 1 = normal to 4 = dyskinesia) were evaluated with a 16-segment model. The ventricular wall was divided into 3 vascular territories. At follow-up, 20 of 32 asynergic vascular territories showed functional recovery, whereas 12 showed no changes. For prediction of functional recovery, LDD SPECT achieved better accuracy than SPECT at rest (87% vs 65%, p <0.05); positive and negative predictive values of LDD SPECT were 90% and 83%, respectively, which was not significantly different from the related LDD echocardiographic values (84% and 69%). Thus, LDD sestamibi SPECT appears to be a promising method for detecting myocardial viability, which provides better accuracy than sestamibi SPECT at rest, and achieves predictive values comparable to those of LDD echocardiography.
Aged↗
Prognostic implications of Tc-99m sestamibi viability imaging and subsequent therapeutic strategy in patients with chronic coronary artery disease and left ventricular dysfunction.
OBJECTIVES: The aim of the study was to verify the prognostic implications of viability detection using baseline-nitrate sestamibi imaging in patients with left ventricular (LV) dysfunction due to chronic coronary artery disease (CAD) submitted to different therapeutic strategies. BACKGROUND: The prognostic meaning of preserved viability in these patients is still debated. Sestamibi is increasingly used for myocardial perfusion scintigraphy and is being accepted also as viability tracer, but no data are available about the relationship between viability in sestamibi imaging, subsequent treatment, and patient's outcome. METHODS: Follow-up data were collected in 105 CAD patients with LV dysfunction who had undergone baseline-nitrate sestamibi perfusion imaging for viability assessment and had been later treated medically (group 1), or submitted to revascularization, which was either complete (group 2A) or incomplete (group 2B). RESULTS: Eighteen hard events (cardiac death or nonfatal myocardial infarction) were registered during the follow-up. A significantly worse event-free survival curve was observed in the patients of group 1 (p < 0.0002) and group 2B (p < 0.03) compared to those of group 2A. Using a Cox proportional hazard model, the most powerful prognostic predictors of events were the number of nonrevascularized asynergic segments with viability in sestamibi imaging (p < 0.003, risk ratio [RR] = 1.4), and the severity of CAD (p < 0.02, RR = 1.28). CONCLUSIONS: Viability detection in sestamibi imaging has important prognostic implications in CAD patients with LV dysfunction. Patients with preserved viability kept on medical therapy or submitted to incomplete revascularization represent high-risk groups.
Aged↗
Detecting myocardial salvage after primary PTCA: early myocardial contrast echocardiography versus delayed sestamibi perfusion imaging.
UNLABELLED: The extent of myocardial salvage after primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI) is variable and cannot be predicted on the basis of either vessel patency or early regional wall motion assessment. The aim of this study was to evaluate the reliability of microvascular integrity, as shown by myocardial contrast echocardiography (MCE), as an indicator of tissue salvage and a predictor of late functional recovery, and to compare MCE with the quantification of tracer activity in sestamibi perfusion imaging. METHODS: Twenty-six patients with AMI who received successful treatment with primary PTCA were examined with MCE during cardiac catheterization immediately before and after vessel recanalization. Myocardial contrast effect was scored as 0 (absent), 0.5 (partial) or 1 (normal). Wall motion was assessed by two-dimensional echocardiography on admission and 1 mo later with a 16-segment model and 4-point score. Resting sestamibi SPECT was collected within 1 wk after AMI. The risk area was defined by MCE as the sum of the segments with no perfusion (score 0) before PTCA. Myocardial viability was defined by MCE as an increase in contrast score in the same segments after PTCA and by sestamibi SPECT as a preserved tracer activity (>60% of peak activity). The functional recovery after 1 mo detected by two-dimensional echocardiography was the reference standard for viability. RESULTS: A total of 50 segments showed perfusion defects before PTCA (risk area). Immediately after PTCA, the MCE score increased in 44 of 50 segments, whereas sestamibi SPECT showed preserved activity in 22 of 50 segments. After 1 mo, the wall motion score decreased in 22 of 50 segments (viable segments) and was unchanged in the remaining 28 segments. Thus, MCE showed a sensitivity of 91% and a specificity of 14% in detecting viable myocardium, whereas sestamibi SPECT showed a lower sensitivity (68%) but a significantly higher specificity (75%; P < 0.00001). The positive predictive values were 45% and 68% for MCE and SPECT (P < 0.005), respectively, and the negative predictive values were 67% and 71%, respectively. On a patient basis, SPECT was more specific (79% versus 21%; P < 0.01) and showed a higher overall predictive accuracy (88% versus 50%; P < 0.01) than MCE. CONCLUSION: The demonstration of microvascular integrity by MCE performed immediately after primary PTCA has a limited diagnostic value in predicting salvaged myocardium. Conversely, tracer activity quantification in resting sestamibi SPECT performed in a later stage is confirmed to be a reliable approach for recognizing myocardial stunning and predicting functional recovery.
Angioplasty, Balloon, Coronary↗
Prediction of post-revascularization functional recovery of asynergic myocardium using quantitative thallium-201 rest-redistribution tomography: has the reverse redistribution pattern an independent significance?
The significance of reverse redistribution on rest-redistribution thallium-201 myocardial scintigraphy is unclear. Previous studies suggested that reverse redistribution segments with normal resting activity include viable myocardium, whilst resting defects with further worsening correspond to scar. We evaluated whether reverse redistribution has an independent significance for the prediction of post-revascularization recovery, particularly as compared with the quantification of redistribution activity. We studied 26 coronary artery disease patients with left ventricular dysfunction, who underwent 201Tl rest-redistribution single-photon emission tomography (SPET) and echocardiography before revascularization. Viability was defined by the detection of wall motion improvement on follow-up echocardiography. 201Tl activity was considered normal if >/=80%, moderately reduced if <80% but >/=50%, and severely decreased if <50%. Reverse redistribution was defined as a defect in redistribution images with >/=10% decrease in relative 201Tl activity compared with the resting value. Reverse redistribution was detected in 33 segments (10%). Baseline dysfunction was equally observed in the reverse redistribution and in the non-reverse redistribution segments (64% vs 56%, P=0.40) and the rate of asynergic segments with post-revascularization recovery was not different between the two groups (33% vs 54%, P=0.11). The rate of functional recovery in redistribution defects without reverse redistribution was 53% in moderate and 30% in severe defects; the corresponding values for the reverse redistribution segments were 50% and 27% (all non-significant versus non-reverse redistribution segments). For the prediction of post-revascularization recovery in asynergic segments, the detection of reverse redistribution on rest-redistribution 201Tl SPET does not add any information to the quantitative analysis of redistribution activity.
Aged↗
Detection of malignant thymoma during myocardial perfusion tomography with Tc-99m sestamibi: potential implications for tumor evaluation and staging.
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Aged↗
Rest-redistribution thallium-201 SPECT to detect myocardial viability.
UNLABELLED: Rest-redistribution 201Tl imaging is currently being used for myocardial viability detection, but the ideal parameters for territory classification have not yet been defined. The aim of this study was to define the optimal criteria for detecting viable myocardium and predicting postrevascularization recovery with rest-redistribution 201Tl SPECT. METHODS: In 29 patients with left ventricular dysfunction, tracer activity within asynergic segments was quantified on rest and redistribution 201Tl SPECT. Viability was defined by the presence of functional recovery, which was detected by comparing wall motion in baseline and follow-up echocardiography. Discriminant function analysis and receiver operating characteristic (ROC) curve analysis were used to evaluate the relationship between 201Tl data and viability. RESULTS: Of 214 dysfunctioning segments (135 a-/dyskinetic), viability was demonstrated in 115 (75 a-/dyskinetic). Both rest and redistribution 201Tl activity in these segments were significantly higher than they were in the nonviable segments (p < 0.0001). Significant (> 10%) reversibility was observed in 39% of the viable and in 36% of the nonviable segments (p = 0.81). Discriminant analysis identified redistribution activity, followed by rest activity, as the most effective predictors of functional recovery. Similar areas were found under the ROC curve for rest (0.68 +/- 0.037) and for redistribution activity (0.70 +/- 0.036) (p = 0.13). ROC curve analysis identified the optimal cutoff for redistribution activity at < 60%, with 147 of 214 (69%) segments correctly classified (sensitivity = 78% and specificity = 58%). In the subset of a-/dyskinetic segments, redistribution activity presented a significantly larger ROC curve area (0.81 +/- 0.038 compared to 0.77 +/- 0.042, p < 0.05), and 103 of 135 (76%) segments were correctly classified (sensitivity = 81% and specificity = 70%). CONCLUSION: Redistribution activity is the most important parameter to be considered in rest-redistribution 201Tl to differentiate viable from nonviable segments; rest activity is also valuable, whereas the meaning of reversibility appears limited. Cutoff values about 60% appear to give the most reasonable balance between sensitivity and specificity.
Coronary Angiography↗
Comparison of baseline-nitrate technetium-99m sestamibi with rest-redistribution thallium-201 tomography in detecting viable hibernating myocardium and predicting postrevascularization recovery.
OBJECTIVES: This study aimed to define the optimal criteria for detecting viable myocardium with rest-redistribution thallium-201 (Tl-201) or baseline-nitrate technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) using discriminant analysis and to compare the accuracy of the two tracers in predicting postrevascularization recovery. BACKGROUND: Rest-redistribution Tl-201 imaging is currently used for detection of myocardial viability, but the optimal variables for territory classification have not yet been defined. Although Tc-99m sestamibi is reportedly less effective than Tl-201, its reliability can be increased by injecting it during nitrate infusion. METHODS: In 35 patients with left ventricular (LV) dysfunction, tracer activity within asynergic coronary territories was quantified on rest and redistribution Tl-201 and baseline and nitrate Tc-99m sestamibi SPECT. Asynergic territory viability was evaluated on the basis of the postrevascularization functional outcome. RESULTS: Percent activity within asynergic territories was significantly influenced by their viability (p < 0.005) and the type of acquisition (p < 0.0001) but not by the tracer used. Discriminant analysis identified redistribution Tl-201 activity and nitrate-induced Tc-99m sestamibi activity change as the two most significant predictors of postrevascularization recovery. The discriminant function defined for Tl-201, including redistribution activity and reversibility, correctly classified 38 of 56 asynergic territories, whereas that for Tc-99m sestamibi, including nitrate-induced activity change and activity in nitrate images, correctly classified 43 territories. CONCLUSIONS: Redistribution activity is more important than reversibility when differentiating viable from nonviable territories using rest-redistribution Tl-201. In Tc-99m sestamibi SPECT, nitrate-induced activity changes are particularly useful in identifying myocardial viability. Baseline-nitrate Tc-99m sestamibi SPECT appears no less effective than rest-redistribution Tl-201 in predicting postrevascularization recovery.
Adult↗
Cardiovascular and renal effects of low-dose atrial natriuretic peptide in compensated cirrhosis.
OBJECTIVES: Patients with cirrhosis and ascites have high plasma levels of atrial natriuretic peptide (ANP). Pharmacological doses of this hormone usually worsen systemic hemodynamics of cirrhotic patients. We assessed whether ANP influences cardiovascular homeostasis and renal function in patients with compensated cirrhosis at plasma levels comparable to those observed in patients with cirrhosis and ascites. METHODS: Radionuclide angiocardiography was performed in eight compensated cirrhotic patients during placebo (three periods of 15 min each) and ANP infusion (2, 4, and 6 pmol/kg.min for 15 min each), together with appropriate blood and urine sampling, to evaluate left ventricular diastolic, systolic, and stroke volume, heart rate, cardiac output, arterial pressure, peripheral vascular resistance, creatinine clearance, urinary sodium excretion, plasma renin activity, plasma aldosterone, norepinephrine and hematocrit. RESULTS: The infusion increased plasma ANP up to levels (52.03 +/- 2.29 pmol/L) comparable with those observed in 35 patients with ascites (46.42 +/- 1.57 pmol/ L). This increment was associated with significant reductions in left ventricular end diastolic volume, stroke volume, cardiac index (from 3.7 +/- 0.7 to 3.1 +/- 0.5 L/min.m2, p < 0.05) and mean arterial pressure (from 96.7 +/- 6.5 to 88.5 +/- 9.5 mmHg, p < 0.05), while heart rate and hematocrit significantly increased. Peripheral vascular resistance did not change. These hemodynamic effects occurred despite significant increases in plasma renin activity and norepinephrine. ANP also induced increases in creatinine clearance, urinary sodium excretion, and fractional sodium excretion. CONCLUSIONS: Low-dose ANP affected cardiovascular homeostasis and renal sodium handling in compensated cirrhosis, suggesting that this hormone may be involved in the pathophysiology of systemic hemodynamic and renal functional abnormalities of cirrhosis.
Aldosterone↗
Left ventricular cavity-to-myocardium count ratio in technetium-99m-sestamibi SPECT in the detection of resting left ventricular dysfunction.
UNLABELLED: The aim of this study was to assess the value of the cavity-to-myocardium count ratio (C/M ratio) calculated in resting 99mTc-sestamibi SPECT images to identify patients with depressed left ventricular ejection fraction (LVEF). METHODS: In the 95 patients studied, the C/M ratio was calculated from the midventricular short-axis slice using regions of interest drawn in the center of the cavity and in the most active area of the ventricular wall; its value was compared with LVEF measured using two-dimensional echocardiography. RESULTS: The C/M ratio correlated with LVEF (r = 0.6, p < 0.000001) and was significantly lower in patients with abnormal LVEF than those with normal LVEF: 0.026 +/- 0.028 versus 0.125 +/- 0.093, p < 0.000001. In the entire patient population, a C/M ratio < 0.07 identified the patients with depressed LVEF with a 94% sensitivity, 71% specificity and 82% accuracy. CONCLUSION: The resting 99mTc-sestamibi C/M ratio is a useful parameter in identifying patients with depressed LVEF directly from the SPECT perfusion images.
Echocardiography↗
Alternative approaches to the prognostic stratification of mild to moderate primary vesicoureteral reflux in children.
PURPOSE: We compared the prognostic stratification of primary vesicoureteral reflux by performing staging voiding cystourethrography in all children with a urinary tract infection or only in those with renal scarring on 99mtechnetium-dimercapto-succinic acid (DMSA) scintigraphy. MATERIALS AND METHODS: Staging voiding cystourethrography and DMSA scintigraphy were performed in 105 children with a urinary tract infection and reflux persistence was assessed by radionuclide cystography after a 2-year followup. RESULTS: Staging voiding cystourethrography revealed no reflux in 51 children (DMSA positive in 3), grades I to II reflux in 21 (DMSA positive in 6) and grade III reflux in 33 (DMSA positive in 19). On followup radionuclide cystography no new reflux was detected, and it was no longer demonstrated in 23 children (8 with grade III and 15 with grades I to II reflux). The finding of grade III reflux on staging voiding cystourethrography had a 76% positive and a 92% negative value for predicting persistent reflux with an 87% predictive accuracy. Limiting the evaluation of voiding cystourethrography data to the 28 children with a positive DMSA scan the combination of renal scarring and grade III reflux had an 84% positive and an 83% negative predictive value with 83% accuracy. This approach would have prevented 77 children from having to undergo voiding cystourethrography. CONCLUSIONS: Performance of staging voiding cystourethrography exclusively in children with renal scarring on a DMSA scan resulted in predictive accuracy that was close to what was achieved by performing voiding cystourethrography in all children with a urinary tract infection. To be able to limit cystourethrography to a select population could prove to be cost-effective.
Case-Control Studies↗
Detection of myocardial viability with 99mTc-labelled myocardial perfusion agents.
Detection of myocardial viability is an important clinical issue in the time course of acute myocardial infarction and in chronic coronary artery disease. The wide availability of myocardial revascularization procedures requires a refinement of specific indications for revascularization whenever left ventricular failure is the most prominent feature of coronary artery disease. In this instance the risk/benefit ratio has to be attentively evaluated with diagnostic tests able to predict favourable changes in regional and global left ventricular function, symptoms, life quality, risk of adverse events and ultimately prognosis. 201Tl has been shown to provide clinically televant information regarding the presence of myocardial viability in patients with extensive regional or global ventricular dysfunction. However, the increasing use of 99mTc labeled myocardial perfusion agents requires a careful evaluation of diagnostic and predictive accuracy of these agents also for the issue of myocardial viability. The widely accepted opinion of a lower predictive accuracy of these agents compared to 201Tl could be no longer true. The available clinical and experimental data indicate, at least for 99mTc-sestamibi, a comparable accuracy when independent and clinically relevant gold standard of viability like post-revascularization functional recovery is considered. Preliminary data indicate that protocols, like nitrate administration, slow infusion or delayed imaging, and accurate quantitation of 99mTc-sestamibi SPECT studies could enhance the predictive accuracy to a level comparable or even better than that of 201Tl and similar to the more demanding PET technology.
Coronary Circulation↗
Technetium-99m-sestamibi imaging with nitrate infusion to detect viable hibernating myocardium and predict postrevascularization recovery.
UNLABELLED: We tested the relationship of nitrate-induced changes in 99mTc-sestamibi perfusion tomography and first-pass radionuclide angiocardiography (FPRNA) with postrevascularization functional recovery of asynergic territories. METHODS: Twenty-eight patients, all with prior infarction and left ventricular dysfunction, underwent two 99mTc-sestamibi rest studies: one under baseline conditions and the other with nitrate infusion. The baseline study was repeated after revascularization. Changes in global and regional perfusion and ventricular function were evaluated by perfusion tomography and FPRNA. Hibermating myocardium was identified by functional recovery in postrevascularization FPRNA. RESULTS: Eleven patients and 31 segments in 19 coronary territories had functional recovery. Nitrate-induced FPRNA changes showed poor agreement with postrevascularization modifications: kappa = 0.24, ns, for the global and kappa = 0.32, p < 0.01 for regional function. The agreement between nitrate-induced and postrevascularization perfusion changes was good both considering the patients (k = 0.57, p < 0.01) and the abnormal coronary territories (k = 0.63, p < 0.0005). The agreement of nitrate-induced perfusion changes with postrevascularization functional outcome was excellent on a patient (k = 1, p < 0.0005), and coronary territory basis (k = 0.82, p < 0.0005). Conversely, the agreement between nitrate and postrevascularization FPRNA was poor: k = 0.18, ns. CONCLUSION: These data suggest that the nitrate-induced changes in 99mTc-sestamibi perfusion imaging are useful to detect hibernating myocardium which recovers its function after revascularization.
Angina Pectoris↗
Nitrate versus rest myocardial scintigraphy with technetium 99m-sestamibi: relationship of tracer uptake to regional left ventricular function and its significance in the detection of viable hibernating myocardium.
Rest technetium 99m-sestamibi uptake may underestimate myocardial viability in asynergic territories. Because nitrate administration was reported to improve thallium 201 uptake in perfusion defects, this study aimed to test the influence of nitrates on 99mTc-sestamibi uptake and on the tracer capability to recognize viable tissue in asynergic segments. In 23 patients with prior infarction and left ventricular dysfunction, regional wall motion was assessed by echocardiography before and after revascularization (13 segments/patient). Group 1 included 97 normokinetic; group 2, 97 hypokinetic; and group 3, 105 akynetic or dyskinetic segments; group 3 was divided into group 3A (72 segments unchanged after revascularization) and group 3B (33 segments with functional recovery). 99mTc-sestamibi uptake was graded using a scoring scheme in the same 13 segments both at rest and, on a separate day, injecting the tracer during isosorbide dinitrate infusion (ISDN). At rest, the mean 99mTc-sestamibi uptake decreased significantly from group 1 through group 3. With ISDN, the mean 99mTc-sestamibi uptake increased in all groups compared with rest, but the increase was significant only in groups 2 and 3, and within the latter, only in group 3B. Thus, with ISDN group 3B was no longer different from group 2. Only 6% of group 3A segments showed an improved uptake with ISDN, versus 33% of group 3B (P < .00005). At rest only 14 of 33 segments of group 3B showed a normal or slightly reduced uptake, whereas these were 25 of 33 with ISDN (P < .02). In conclusion, the acute administration of ISDN increases the uptake of 99mTc-sestamibi mainly in those asynergic territories that show postrevascularization functional recovery. Therefore, ISDN 99mTc-sestamibi imaging might improve the tracer capability to detect viable hibernating myocardium.
Angioplasty, Balloon, Coronary↗