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PubMed1989

Noninvasive cardiac risk stratification of diabetic and nondiabetic uremic renal allograft candidates using dipyridamole-thallium-201 imaging and radionuclide ventriculography.

The ability of noninvasive risk stratification using dipyridamole-thallium-201 (Tl-201) imaging and radionuclide ventriculography to predict perioperative and long-term cardiac events (myocardial infarction or cardiac death) was evaluated in 36 uremic diabetic and 29 nondiabetic candidates for renal allograft surgery. Of the 35 patients who underwent renal allograft surgery 8 +/- 7 months after the study, none had transient Tl-201 defects (although 13 had depressed left ventricular ejection fraction) and none developed perioperative cardiac events. During a mean follow-up of 23 +/- 11 months, 6 (9%) patients developed cardiac events. Logistic regression analysis was used to compare the predictive value of clinical data (including age, sex, diabetes, chest pain history, allograft recipient) and radionuclide data. Presence of transient Tl-201 defect and left ventricular ejection fraction were the only significant predictors of future cardiac events (p less than 0.01). No other patient variables, including diabetes or receiving a renal allograft, had either univariate or multivariate predictive value. All 3 patients with transient Tl-201 defects had cardiac events compared with only 3 of 62 (5%) patients without transient Tl-201 defect (p less than 0.0001). Mean left ventricular ejection fraction was lower in patients with cardiac events (44 +/- 13%) compared with patients without cardiac events (57 +/- 9%, p less than 0.005). Overall, 5 of 6 patients with cardiac events had either transient Tl-201 defects or depressed left ventricular ejection fraction. Dipyridamole-Tl-201 imaging and radionuclide ventriculography may be helpful in identifying uremic candidates for renal allograft surgery who are at low risk for perioperative and long-term cardiac events.

Adult↗
PubMed1990

Usefulness of semiquantitative analysis of dipyridamole-thallium-201 redistribution for improving risk stratification before vascular surgery.

Preoperative dipyridamole-thallium-201 scanning is sensitive in identifying patients prone to ischemic cardiac complications after vascular surgery, but most patients with redistribution do not have an event after surgery. Therefore, its positive predictive value is limited. To determine which patients with thallium redistribution are at highest risk, dipyridamole-thallium-201 images were interpreted semiquantitatively. Sixty-two consecutive patients with redistribution on preoperative dipyridamole-thallium-201 planar imaging studies were identified. Each thallium scan was then analyzed independently by 2 observers for the number of myocardial segments out of 15, the number of thallium views out of 3 and the number of coronary artery territories with redistribution. Seventeen patients (27%) had postoperative ischemic events, including unstable angina pectoris, ischemic pulmonary edema, myocardial infarction and cardiac death. Thallium predictors of ischemic operative complications included thallium redistribution greater than or equal to 4 myocardial segments (p = 0.03), greater than or equal to 2 of the 3 planar views (p = 0.005) and greater than or equal to 2 coronary territories (p = 0.007). No patient with redistribution in only 1 view had an ischemic event (0 of 15). Thus, determining the extent of redistribution by dipyridamole-thallium-201 scanning improves risk stratification before vascular surgery. Patients with greater numbers of myocardial segments and greater numbers of coronary territories showing thallium-201 redistribution are at higher risk for ischemic cardiac complications. In contrast, when the extent of thallium redistribution is limited, there is a lower risk despite the presence of redistribution.

Aged↗
PubMed1990

Risk stratification of single or double vessel coronary artery disease and impaired left ventricular function using exercise radionuclide angiography.

Patients with 3-vessel coronary artery disease (CAD) and normal left ventricular (LV) function have a worse prognosis if they manifest ischemia during exercise testing. The present study determines if exercise radionuclide angiography can aid in the risk stratification of patients with 1- or 2-vessel CAD and impaired LV function (ejection fraction less than 50%). Sixty-five consecutive patients with these findings were followed for a median duration of 24 months (range 12 to 49). Eleven of the 65 patients (17%) had severely ischemic exercise radionuclide angiograms, defined as: a decrease in ejection fraction with exercise; greater than or equal to 1.0 mm of ST-segment depression; and peak exercise workload less than or equal to 600 kg-m/min. During follow-up 11 patients had initial significant cardiac events: 4 cardiac deaths, 1 cardiac arrest, 4 myocardial infarctions and 2 bypass or angioplasty procedures for unstable angina greater than or equal to 3 months after the exercise study. Four of 11 patients (36%) with severely ischemic exercise radionuclide angiograms had events, compared to 7 of 54 patients (13%) without ischemic radionuclide angiograms. Event-free survival at 18 months was 73% for patients with severe exercise ischemia versus 92% for those without ischemia (p less than 0.05). Univariate analysis showed that severe ischemia on radionuclide angiography was the only variable of several tested that significantly predicted future cardiac events (chi-square = 8.16, p less than 0.005). Among patients with 1- or 2-vessel CAD and impaired resting LV function, severe ischemia on exercise radionuclide angiography identifies a subgroup at high risk for future cardiac events.

Coronary Disease↗
PubMed1992

Preoperative coronary artery disease risk stratification based on dipyridamole imaging and a simple three-step, three-segment model for patients undergoing noncardiac vascular surgery or major general surgery.

A 3-step, 3-segment scintigraphic model was developed to improve the accuracy of dipyridamole-thallium imaging for preoperative cardiac risk assessment and to simplify the prognostic interpretation of the images. The model was developed in a pilot study of 60 patients and validated in a group of 355 patients referred for vascular and major general surgery. Study end points included myocardial infarction and cardiac death. Step 1: The postoperative cardiac event rate was 1.3% in 225 patients with normal anterior, inferio- and posterolateral segment perfusion and without transient left ventricular dipyridamole-induced cavitary dilation. Step 2: The physiologic rationale for step 2 consists of identifying patients who are most likely to have left main, 3-vessel or high-risk 2-vessel coronary artery disease or a significant amount of jeopardized myocardium in the territory of a critical coronary stenosis. Of 29 patients with either reversible defects of all 3 segments, transient cavitary dilation, or at least 1 severe grade 3/3 reversible defect, 52% (15 of 29) sustained a postoperative cardiac event. Step 3: The remaining 101 patients were stratified according to age greater than 70 years (p = 0.01), presence of diabetes (p = 0.0004) and the number of segments displaying reversible defects (1 or 2) with cardiac event rates ranging from 5 to 36%. The 3-step, 3-segment model is a useful alternative to the conventional interpretation of dipyridamole myocardial perfusion images for the purpose of quick and efficient preoperative risk stratification based on the rationale of correlating surgical risk with the amount of potentially ischemic myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Relative value of clinical variables, treadmill stress testing, and Holter ST monitoring for postinfarction risk stratification.

The aim of this study was to compare the roles of clinical assessment, treadmill stress testing, and Holter ST analysis for postinfarction risk stratification in patients treated with thrombolysis. The study group consisted of 256 consecutive patients, all of whom underwent Holter ST monitoring early (mean 83 hours, range 48 to 180) after admission. Of these, 12 were excluded from the analysis either because Holter recordings were of insufficient quality (n = 6), or because reinfarction occurred within 24 hours of monitoring (n = 6). In the remaining 244 patients, 43 sustained a recurrent event (death, reinfarction, unstable angina) over the 8-month (range 3 to 12) follow-up period, and an additional 14 patients required revascularization. At multivariate event-free survival analysis, Killip class > or = 2 and Holter ST shift were independently predictive of the outcome. The strongest predictor was Holter ST shift at a cumulative duration of > 60 minutes. Of the 232 patients eligible for stress testing (12 sustained an event between Holter monitoring and the scheduled stress test), 196 were able to perform the test. The variable "inability to perform a stress test" was not independently predictive of outcome and did not influence the multivariate analysis. When clinical, Holter, and stress test variables were taken into account in patients who performed a stress test, Killip class was the only independent predictor of outcome (event-free survival). When revascularization was included as an end point, Holter ST shift was the only independent predictor of outcome. In conclusion, a significant proportion of recurrent events after thrombolysis occurs very early, before stress testing can be performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Systolic time intervals after phenylephrine administration for early stratification of patients after acute myocardial infarction.

This study was designed to assess the usefulness of the changes in left ventricular (LV) systolic time intervals after phenylephrine administration for detecting high-risk patients soon after acute myocardial infarction by correlation with the angiographic and ventriculographic findings. The procedure was performed in 76 consecutive patients (group I) on the fourth postinfarction day and in 12 normal subjects (group II) free of coronary artery disease. In 20 patients with LV ejection fraction < or = 40% (subgroup IA) the preejection period (PEP)/LV ejection time (ET) ratio increased from 0.410 +/- 0.107 to 0.535 +/- 0.102 (p = 0.01) after phenylephrine, whereas in the remaining 56 patients (subgroup IB) with LV ejection fraction > 40% and in the 12 normal subjects the PEP/LVET increased nonsignificantly. Of patients with LV ejection fraction > 40% a subset of 20 patients was distinguished with proximal stenosis in both left anterior descending and either a dominant right or left circumflex coronary artery (subset IB-a). In these the PEP/LVET increased from 0.347 +/- 0.056 to 0.445 +/- 0.019 (p = 0.0001) after phenylephrine, whereas in the remaining 36 patients (subset IB-b) without proximal lesions in 2 main arteries the PEP/LVET increased nonsignificantly. In conclusion, the PEP/LVET response to phenylephrine administration early after acute myocardial infarction is a precise, safe, noninvasive bedside method for early stratification of these patients.

Adult↗
PubMed1994

Risk stratification using the Society of Thoracic Surgeons Program.

In an era of progressive cost containment and public scrutiny, the wisdom of aggressive surgical therapy for high-risk candidates has been questioned. At our center in the previous 24 months, 728 patients with coronary artery disease were entered into The Society of Thoracic Surgeons national database, and the hospital outcomes plus length of stay were analyzed. Patients were separated according to the predicted mortality based on the groupings in The Society of Thoracic Surgeons database: 0 to 5% (453 patients); 5% to 10% (126 patients); 10% to 20% (96 patients); 20% to 30% (17 patients); and 30% and greater (36 patients). There was a close correlation with the predicted rates of mortality. Importantly, the preoperative risk stratification demonstrated a strong correlation with the significant morbidity and excessive length of stay in the highest-risk groups (predicted risk of 20% to > or = 30%). The incidences of the most common complications in the group with the highest predicted risk (> or = 30%) were 28%, renal failure; 33%, ventilator dependence; and 17%, cardiac arrest. In addition, at short-term follow-up (6 to 8 months), a 24.3% mortality was identified in patients with a predicted mortality that exceeded 20%. These data quantify the risks and morbidities associated with the care of seriously ill patients with coronary artery disease and demonstrate the need for professional and public discussions focusing on the association of a high preoperative risk status and the consumption of resources.

Aged↗
PubMed1987

Cell surface and cytoskeletal changes associated with epidermal stratification and differentiation in organ cultures of embryonic human skin.

Embryonic and fetal human epidermis differentiates in organ culture in an age dependent, though accelerated, manner. The older the specimen the less time is required for epidermal differentiation. Morphological markers of epidermal differentiation, including the different epidermal strata, keratohyalin granules, lamellar granules, and cornified cell envelopes, are formed in a manner that is faithful to development in vivo. The high molecular weight, "differentiation specific" (67 and 56.5 kDa) keratins are also expressed in these cultures, even in the absence of morphological evidence for keratinization. Unstratified, embryonic epidermis was found to stratify overnight in culture. The time course of cell surface changes, detected by lectin binding, and cytoskeletal changes, detected by expression of the high molecular weight keratins, was followed in these cultures. Peanut agglutinin (PNA) binding sites appeared overnight in culture coincidently with epidermal stratification while expression of the 67 and 56.5 kDa keratins was not detected until the third day of culture. The possible significance of these results is discussed.

Cell Differentiation↗
PubMed1995

Evidence for gammacerane as an indicator of water column stratification.

A new route for the formation of gammacerane from tetrahymanol is proposed; in addition to dehydration and hydrogenation, sulphurisation and early C-S cleavage are shown to be important in the pathway of formation, especially in marine sediments. Evidence is twofold. First, relatively large amounts of the gammacerane skeleton are sequestered in S-rich macromolecular aggregates formed by natural sulphurisation of functionalised lipids. Selective cleavage of polysulphide linkages with MeLi/MeI led to formation of 3-methylthiogammacerane, indicating that the gammacerane skeleton is primarily bound via sulphur at position 3, consistent with the idea that tetrahymanol (or the corresponding ketone) is the precursor for gammacerane. Second, upon mild artificial maturation of two sediments using hydrous pyrolysis, gammacerane is released from S-rich macromolecular aggregates by cleavage of the relatively weak C-S bonds. The stable carbon isotopic compositions of gammacerane and lipids derived from primary producers and green sulphur bacteria in both the Miocene Gessoso-solfifera and Upper Jurassic Allgau Formations indicate that gammacerane is derived from bacterivorous ciliates which were partially feeding on green sulphur bacteria. This demonstrates that anaerobic ciliates living at or below the chemocline are important sources for gammacerane, consistent with the fact that ciliates only biosynthesize tetrahymanol if their diet is deprived of sterols. This leads to the conclusion that gammacerane is an indicator for water column stratification, which solves two current enigmas in gammacerane geochemistry. Firstly, it explains why gammacerane is often found in sediments deposited under hypersaline conditions but is not necessarily restricted to this type of deposits. Secondly, it explains why lacustrine deposits may contain abundant gammacerane since most lakes in the temperate climatic zones are stratified during summer.

Animals↗
PubMed1985

Consideration of covariates and stratification in sample size determination for survival time studies.

Sample size determination for survival time studies is discussed, taking into account stratification. We present formulas and tables which also apply in the case of multicenter clinical trials. In addition, the same method is used to estimate the sample size requirement when a covariate is grouped into strata. Simulation studies compare the results to covariate adjustment by the Cox proportional hazards model.

Follow-Up Studies↗
PubMed1995

Stratification of injury severity using energy expenditure response in surgical infants.

AIM OF STUDY: Injury severity stratification has important clinical outcome significance and can influence nutritional management. Although surgery alone has been shown not to increase measured energy expenditure (MEE) substantially, large increases in MEE can result from severe underlying acute illness, which frequently necessitates surgery (like sepsis or intense inflammation). The authors hypothesized that the magnitude and duration of the MEE response to surgery associated with a severe preoperative acute injury would exceed that of surgery in which no substantial preoperative stress was present, thus representing an index of overall injury severity in surgical infants. METHODS: MEE (kcal/kg/d) was determined on postoperative days (POD) 2, 5, and 8 in 12 infants (average age, 47 days) after two separate injury insults (at least 8 days apart). In each patient, one operation resulted in a peak serum C-reactive protein (CRP) concentration of less than 6.5 mg/dL (low stress), and the second operation, preoperatively associated with sepsis or a major inflammatory insult, resulted in a peak CRP of more than 6.5 mg/dL (high stress). Data were paired so that each child served as his or her own control. The initial basal protein-calorie delivery was similar in both groups. MAIN RESULTS: The mean peak CRP values were 14.1 +/- 10.7 mg/dL (high stress) and 4.1 +/- 2.3 mg/dL (low stress) and returned to normal levels earlier (before POD 8) after injury insult in the low-stress group. Analysis of energy expenditure on POD 2 demonstrated significantly elevated mean MEE values in the high-stress group (58.0 +/- 12.2 kcal/kg/d v 39.4 +/- 9.5 kcal/kg/d in the low-stress group; P = .0001). In contrast, analysis of POD 8 energy expenditure showed significantly lower mean MEE values in the high-stress group (50.7 +/- 12.0 kcal/kg/d) v (66.4 +/- 15.1 kcal/kg/d in the low-stress group; P = .0118) group. CONCLUSION: The early (POD 2) hypermetabolic response to injury as determined by MEE effectively differentiated the two stress groups. This finding suggests that acute underlying illness is an important determinant of postoperative MEE. Furthermore, in the low-stress group, serial CRP levels returned to normal earlier, associated with significantly greater late (POD 8) MEE values. Because MEE is directly proportional to growth rate in healthy infants, and growth is retarded during acute metabolic stress, these findings suggest that increased energy is utilized for growth recovery following the earlier resolution of the acute injury response in the low-stress group. These data indicate that serial postoperative MEE can be used to stratify injury severity and may be an effective parameter to monitor the return of normal growth metabolism in surgical infants.

Analysis of Variance↗
PubMed1993

How many stratification factors are "too many" to use in a randomization plan?

The issue of stratification and its role in patient assignment has generated much discussion, mostly focused on its importance to a study or lack thereof. This report focuses on a much narrower problem: assuming that stratified assignment is desired, how many factors can be accommodated? This problem is investigated for two methods of balanced patient assignments; the first is based on the minimization method of Taves and the second on the commonly used method of stratified assignment. Simulation results show that the former method can accommodate a large number of factors (10-20) without difficulty but that the latter begins to fail if the total number of distinct combination of factor levels is greater than approximately n/2. The two methods are related to a linear discriminant model, which helps to explain the results.

Computers↗
PubMed1996

International stratification and the health of women: an empirical comparison of alternative models of world-system position.

Women's health status is investigated in the context of stratification in the world-system. We investigate three alternative conceptualizations of the world-system for their effects on women's health status, using country-level data. The models investigate the effects of world-system position, military expenditures, and health resources on women's health status. Comparison of the alternative conceptualizations of world-system position indicate that a continuous model is only negligibly better than three- or five-block models at explaining women's health status. Regardless of how it is measured, world-system position has dramatic effects on women's health.

Economics↗
PubMed1989

Risk stratification in patients with first non-Q wave infarction: limited value of the early low level exercise test after uncomplicated infarcts. The Multicenter Post-Infarction Research Group.

Risk stratification using clinical and historical variables plus early low level exercise testing was performed in 141 patients with a first non-Q wave myocardial infarction. The 111 patients who performed the exercise test had a 3.6% cardiac mortality rate in the first year compared with 13.3% in the 30 patients who could not exercise (p = 0.063), and a 1 year incidence rate of recurrent cardiac events (cardiac death or recurrent nonfatal myocardial infarction) of 10.8% compared with 23.3% (p = 0.127). Patients who developed ischemia (ST depression or angina) during the test had an increased incidence of cardiac events in the year after the infarction (odds ratio greater than 3, p less than 0.05). When patients were subgrouped by the presence or absence of pulmonary congestion, the discriminatory value of the exercise test was seen to reside primarily in the cohort with pulmonary congestion. For example, ST depression during exercise in this group identified patients with a 71% incidence of cardiac events in the year after the infarction compared with 5.3% for those without ST depression (odds ratio 45, p = 0.002). In the patients without pulmonary congestion, the exercise test had no discriminatory value. It is concluded that early low level exercise testing has a limited role after an uncomplicated non-Q wave infarction, but is useful in patients with clinical markers of higher risk.

Electrocardiography↗
PubMed1994

Risk stratification for arrhythmic events in patients with nonischemic dilated cardiomyopathy and nonsustained ventricular tachycardia: role of programmed ventricular stimulation and the signal-averaged electrocardiogram.

OBJECTIVES: This study investigated prediction of arrhythmic events by the signal-averaged electrocardiogram (ECG) and programmed stimulation in patients with nonischemic dilated cardiomyopathy. BACKGROUND: Risk stratification in patients with nonischemic dilated cardiomyopathy remains controversial. METHODS: Eighty patients with nonischemic dilated cardiomyopathy and spontaneous nonsustained ventricular tachycardia underwent signal-averaged electrocardiography (both time-domain and spectral turbulence analysis) and programmed stimulation. All patients were followed up for a mean of 22 +/- 26 months. RESULTS: Sustained monomorphic ventricular tachycardia was induced in 10 patients (13%), who all received amiodarone. The remaining 70 patients were followed up without antiarrhythmic therapy. Of the 80 patients, 15% had abnormal findings on the time-domain signal-averaged ECG, and 39% had abnormal findings on spectral turbulence analysis. Time-domain signal-averaged electrocardiography had a better predictive accuracy for induced ventricular tachycardia than spectral turbulence analysis (88% vs. 66%, p < 0.01). During follow-up, there were 9 arrhythmic events (5 sudden deaths, 4 spontaneous ventricular tachycardia/fibrillation) and 10 nonsudden cardiac deaths. Cox regression analysis showed that no variables predicted arrhythmic events or total cardiac deaths. The 2-year actuarial survival free of arrhythmic events was similar in patients with or without abnormal findings on the signal-averaged ECG or induced ventricular tachycardia. CONCLUSIONS: In patients with nonischemic dilated cardiomyopathy, 1) there is a strong correlation between abnormal findings on the time-domain signal-averaged ECG and induced ventricular tachycardia, but both findings are uncommon; and 2) normal findings on the signal-averaged ECG, as well as failure to induce ventricular tachycardia, do not imply a benign outcome.

Actuarial Analysis↗
PubMed1996

Meta-analysis of intravenous dipyridamole-thallium-201 imaging (1985 to 1994) and dobutamine echocardiography (1991 to 1994) for risk stratification before vascular surgery.

OBJECTIVES: This study evaluated the prognostic value of abnormal test results with pharmacologic stress with regard to perioperative and long-term outcomes in a large population of candidates for vascular surgery. BACKGROUND: Although numerous studies have demonstrated the prognostic value of dipyridamole-thallium-201 myocardial perfusion and dobutamine echocardiography in vascular surgery candidates, a synopsis of predictive estimates is difficult because of individual study variability in pretest clinical risk, sample size and study design. METHODS: A systematic review of published reports on preoperative pharmacologic stress risk stratification from the MEDLINE data base (1985 to 1994) identified 10 reports on dipyridamole-thallium-201 myocardial perfusion (1,994 patients) and 5 on dobutamine stress echocardiography (446 patients). Random effects models were used to calculate summary odds ratios and 95% confidence intervals. RESULTS: Summary odds ratios for death or myocardial infarction and secondary cardiac end points were greater for dobutamine echocardiographic dyssynergy (14- to 27-fold) than for dipyridamole-thallium-201 redistribution (4-fold); wider confidence intervals were noted with dobutamine echocardiography. Pretest coronary disease probability was correlated with the positive predictive value of a reversible thallium-201 defect (r=0.70), increasing sixfold from low to high risk patient subsets. Cardiac event rates were low in patients without a history of coronary artery disease (1% in 176 patients) compared with patients with coronary disease and a normal or fixed-defect pattern (4.8% in 83 patients) and one or more thallium-201 redistribution abnormality (18.6% in 97 patients, p=0.0001). CONCLUSIONS: Meta-analysis of 15 studies demonstrated that the prognostic value of noninvasive stress imaging abnormalities for perioperative ischemic events is comparable between available techniques but that the accuracy varies with coronary artery disease prevalence.

Adrenergic beta-Agonists↗
PubMed1996

Myocardial infarction patients in the 1990s--their risk factors, stratification and survival in Canada: the Canadian Assessment of Myocardial Infarction (CAMI) Study.

OBJECTIVES: This study sought to evaluate the in-hospital and postdischarge mortality of patients with an acute myocardial infarction in the 1990s. BACKGROUND: The widespread implementation of therapeutic interventions that modify the natural history of coronary artery disease has led to changes in the profile and survival of patients with an acute myocardial infarction. Although data exist for selected subsets of patients with an acute myocardial infarction, at this time there is little recent prospective information on all patients presenting with an acute myocardial infarction, particularly for survival after hospital discharge. METHODS: All patients < or = 75 years old presenting with an acute myocardial infarction between July 1, 1990 and June 30, 1992 at nine Canadian hospitals were prospectively evaluated and followed up for 1 year. From November 1991, patients of all ages were included. In two centers, recruitment continued until December 31, 1992. A total of 3,178 patients were recruited. RESULTS: The in-hospital mortality rate of patients < or = 75 years old was 8.4%, and that at 1 year after hospital discharge was 5.3%. For patients of all ages recruited after November 1, 1991, the in-hospital mortality rate was 9.9% and 7.1% for 1 year after hospital discharge. For patients < or = 75 years old, age carried an independent in-hospital but no post discharge risk. Female patients had a twofold greater risk of dying in hospital. After hospital discharge, only 1.7% of patients < or = 75 years old and 1.9% of patients of all ages died of a presumed arrhythmic death. Premature ventricular contractions had no independent prognostic value. The relatively low in-hospital (5.3%) and postdischarge (6.1%) reinfarction rate may have contributed to improved survival. A greater reinfarction rate in patients >75 years old (17.4% vs. 9.6%, p < 0.001) may have contributed to their poorer outcome. CONCLUSIONS: One-year mortality after acute myocardial infarction continues to decrease, and changes in the prognostic value of traditional methods of risk stratification have occurred.

Age Factors↗
PubMed1996

Effective risk stratification using exercise myocardial perfusion SPECT in women: gender-related differences in prognostic nuclear testing.

OBJECTIVES: This study was designed to evaluate the incremental prognostic value over clinical and exercise variables of rest thallium-201/exercise technetium-99m sestamibi single-photon emission computed tomography (SPECT) in women compared with men and to determine whether this test can be used to effectively risk stratify patients of both genders. BACKGROUND: To minimize the previously described gender-related bias in the evaluation of coronary artery disease in women, there is a need to identify a noninvasive testing strategy that is able to accurately and effectively risk stratify women. METHODS: We identified 4,136 consecutive patients (2,742 men, 1,394 women) who underwent dual-isotope SPECT. The incremental value of nuclear testing was determined using both a stepwise Cox proportional hazards model and Kaplan-Meier survival analysis. Receiver operating characteristic curve analysis was performed to determine test discrimination for high risk patients in men and women. RESULTS: The patient population was followed up for 20 +/- 5 months for events (cardiac death or nonfatal myocardial infarction). During this time, 63 myocardial infarctions and 32 cardiac deaths occurred in the men, and 31 myocardial infarctions and 14 cardiac deaths occurred in the women. Nuclear testing significantly stratified both men and women irrespective of their rest electrocardiogram. Cox proportional hazards analysis revealed that nuclear testing added incremental prognostic value in both men and women after inclusion of the most predictive clinical exercise variables (overall chi-square 89 in men vs. 120 in women, p < 0.005). Kaplan-Meier survival analysis demonstrated that nuclear testing further stratified men and women with both intermediate to high and low prescan likelihoods of coronary artery disease (p < 0.005 for all). Receiver operating characteristic curve analysis demonstrated superior discrimination for the nuclear scan results in identifying high risk women than men (area under the curve: 0.84 +/- 0.03 vs 0.71 +/- 0.03 in men, p < 0005). The odds ratio comparing event rates in patients with women than in men, suggesting superior stratification using nuclear testing in women. CONCLUSIONS: Dual-isotope myocardial perfusion imaging yields incremental prognostic value in both men and women. This modality identifies low risk women and men equally well but relatively high risk women more accurately than relatively high risk men and, thus, is able to stratify women more effectively than men.

Bias↗