Biomedical subjects
Publications and source records attributed to Raymond J Gibbons.
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In 1999, the American College of Physicians (ACP), then the American College of Physicians-American Society of Internal Medicine, and the American College of Cardiology/American Heart Association (ACC/AHA) developed joint guidelines on the management of patients with chronic stable angina. The ACC/AHA then published an updated guideline in 2002, which the ACP recognized as a scientifically valid review of the evidence and background paper. This ACP guideline summarizes the recommendations of the 2002 ACC/AHA updated guideline and underscores the recommendations most likely to be important to physicians seeing patients in the primary care setting. This guideline is the first of 2 that will provide guidance on the management of patients with chronic stable angina. This document will cover diagnosis and risk stratification for symptomatic patients who have not had an acute myocardial infarction or revascularization procedure in the previous 6 months. Sections addressing asymptomatic patients are also included. Asymptomatic refers to patients with known or suspected coronary disease based on history or on electrocardiographic evidence of previous myocardial infarction, coronary angiography, or abnormal results on noninvasive tests. A future guideline will cover pharmacologic therapy and follow-up.
In a nonrandomized feasibility study of therapeutic hypothermia in acute myocardial infarction, 18 patients were treated with endovascular cooling (Alsius, Irvine, California) as adjunctive therapy to primary percutaneous coronary intervention to assess measures of infarct size (area under the curve creatinine kinase-MB and technetium-99m single-photon emission computed tomography sestamibi) and the quality of myocardial perfusion (continuous ST-segment monitoring). Periprocedural endovascular cooling successfully decreased core body temperature (median 33.5 degrees C) and was well tolerated, which supports the evaluation of adjunctive hypothermia in pivotal trials to limit infarct size and decrease reperfusion injury.
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OBJECTIVES: The purpose of this study was to determine whether a previously validated clinical score (CS) could identify patients with a low-risk Duke treadmill score who had a higher risk of adverse events and, therefore, in whom myocardial perfusion imaging would be valuable for risk stratification. BACKGROUND: Current American College of Cardiology/American Heart Association guidelines recommend using a standard exercise test without imaging as the initial test in patients who have an interpretable electrocardiogram and are able to exercise. METHOD: We studied 1,461 symptomatic patients with low-risk Duke treadmill scores (> or =5) who underwent myocardial perfusion imaging. The CS was derived by assigning one point to each of the following variables: typical angina, history of myocardial infarction, diabetes, insulin use, male gender, and each decade of age over 40 years. A CS cutoff > or =5 or <5 was used to categorize patients as high risk (n = 303 [21%]) or low risk (n = 1,158 [79%]). Perfusion scans were categorized as low, intermediate, or high risk on the basis of the global stress score (GSS). RESULTS: High-risk scans were more common in patients with a high-risk CS (26.4% vs. 9.5%, p < 0.0001). The CS and GSS were significant independent predictors of cardiac death. However, in patients with a low CS, seven-year cardiac survival was excellent, regardless of the GSS (99% for normal scans, 99% for mildly abnormal scans, and 99% for severely abnormal scans). In contrast, patients with a high CS had a lower seven-year survival rate (92%), which varied with GSS (94% for normal scans, 94% for mildly abnormal scans, and 84% for severely abnormal scans; p < 0.001). CONCLUSIONS: In symptomatic patients with low-risk Duke treadmill scores and low clinical risk, myocardial perfusion imaging is of limited prognostic value. In patients with low-risk Duke treadmill scores and high clinical risk, annual cardiac mortality (>1%) is not low, and myocardial perfusion imaging has independent prognostic value.
BACKGROUND: Dipyridamole and adenosine cause frequent side effects as a result of nonspecific adenosine receptor stimulation. Selective agonism of the adenosine A2A receptor should result in a similar degree of coronary vasodilation (and thus similar perfusion images) with fewer side effects. METHODS AND RESULTS: In a multicenter, randomized, single-blind, 2-arm crossover trial, 240 patients underwent 2 single photon emission computed tomographic (SPECT) imaging studies in random order, first after pharmacological stress with adenosine and a second study with the selective adenosine A2A receptor agonist binodenoson, using 1 of 4 dosing regimens. Safety, tolerability, and SPECT image concordance between the 2 agents were examined. Exact categorical agreement in the extent and severity of reversible perfusion defects ranged from 79% to 87%, with kappa values from 0.69 to 0.85, indicating very good to excellent agreement between binodenoson and adenosine. The risk of any safety event/side effect was significantly lower with any dose of binodenoson than with adenosine (P< or =0.01) because of a dose-related reduction in subjective side effects, as objective events were infrequent. There was a reduction in the severity of chest pain, dyspnea, and flushing in all binodenoson doses compared with adenosine (P<0.01), and the magnitude of severity reduction was dose-related. CONCLUSIONS: The selective adenosine A2A receptor agonist binodenoson results in an extent and severity of reversible perfusion defects on SPECT imaging similar to nonselective adenosine receptor stimulation, accompanied by a dose-related reduction in the incidence and severity of side effects.
BACKGROUND: Successful reperfusion after acute ST-elevation myocardial infarction improves prognosis. Among the different electrocardiographic markers of reperfusion, sum ST resolution is considered the hallmark of reperfusion, but is cumbersome to use. METHODS: To assess the usefulness of a single lead ST resolution at 90 minutes after fibrinolysis compared with the sum ST resolution in predicting Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow, we used prospectively collected data from the Limitation of Myocardial Injury Following Thrombolysis in Acute Myocardial Infarction (LIMIT-AMI) study. All patients had electrocardiograms recorded at presentation and 90 minutes and a coronary angiogram 90 minutes after fibrinolysis. RESULTS: Infarction artery patency was assessed in 238 patients with 4 different ST resolution criteria: single lead ST resolution > or =50% and > or =70% and sum ST resolution > or =50% and > or =70%. The most sensitive criteria for TIMI grade 3 flow was single lead ST resolution > or =50% (sensitivity rate, 70%; specificity rate, 54%), whereas sum ST resolution > or =70% was most the specific criteria (sensitivity rate, 45%; specificity rate, 79%). The proportion of patients with TIMI grade 3 flow was similar in all 4 ST resolution groups (P =.84). Pre-discharge infarction size and ejection fraction were also similar. No single lead or sum lead measure of ST resolution was significantly associated with an increased risk of death, heart failure, or reinfarction. CONCLUSION: We propose that single lead ST-resolution > or =50% as an optimal electrocardiographic indicator for successful reperfusion 90 minutes after fibrinolysis. This simple electrocardiographic measure should be combined with bedside clinical and hemodynamic assessment to optimize decision making after fibrinolysis.
BACKGROUND: Patients with diabetes without clinically apparent coronary artery disease are at increased risk of cardiac death. The value of screening stress testing in these patients remains controversial. The goal of this study was to examine the yield of stress single-photon emission computed tomography (SPECT) in asymptomatic diabetic patients. METHODS: The results of stress SPECT in patients without prior myocardial infarction or coronary revascularization were compared in asymptomatic diabetics (n = 1738) versus symptomatic diabetic patients (n = 2998), asymptomatic nondiabetic patients (n = 6215), and symptomatic nondiabetic patients (n = 16,214). RESULTS: Abnormal scans were present in 58.6% of asymptomatic diabetic patients, approximately equal to the percentage in symptomatic diabetic (59.5%) (P = not significant) and higher than in asymptomatic nondiabetic (46.2%) (P <.001) and symptomatic nondiabetic (44.4%) (P <.001) patients. The breakdown of high-risk scans followed a similar pattern in the 4 patient subsets: asymptomatic diabetic, 19.7% versus symptomatic diabetic, 22.2% (P =.051); asymptomatic nondiabetic, 11.1% (P <.001); and symptomatic nondiabetic, 12.5% (P <.001). Patients with diabetes had more electrocardiographic and scan evidence for silent myocardial infarction versus those without diabetes. CONCLUSIONS: Asymptomatic diabetic patients have a high prevalence of both abnormal and high-risk SPECT scans. The finding that approximately 1 in 5 of these individuals has a high-risk scan suggests a potentially more widespread application of screening stress SPECT in asymptomatic diabetic patients to identify those with severe coronary artery disease.
BACKGROUND: We retrospectively identified heart failure patients with suspected ischemic heart disease who underwent myocardial perfusion imaging (MPI) to examine the relationship of MPI findings to subsequent patient outcomes. METHODS: The study group consisted of 336 patients with heart failure, left ventricular ejection fraction <45%, and suspected ischemic heart disease who underwent MPI during the period of January 1991 to December 31, 1997. Patients were divided in 3 subgroups: group A (n = 137), large fixed perfusion defects; group B (n = 77), large reversible perfusion defects; and group C (n=122), absence of a large reversible or fixed perfusion defect. RESULTS: Overall, the 5-year mortality rate was high at 49.2% +/- 3.1%. Mortality was significantly different (P =.009) among the 3 subgroups. Groups A and B had a similar 5-year mortality rates >50%. Group C had a relatively better, but still substantial 5-year mortality rate of 40%. The overall revascularization rate was low (9.7% in 5 years). CONCLUSION: These results indicate a high 5-year mortality rate in patients with large myocardial perfusion defects (fixed or reversible) and presumably an ischemic etiology for their heart failure. Patients with no large or absent perfusion defects had more favorable survival outcomes.
BACKGROUND: Both epicardial and myocardial perfusion have been associated with clinical outcomes in the setting of ST elevation myocardial infarction (STEMI), and the performance of adjunctive/rescue percutaneous coronary intervention (PCI) may further improve clinical outcomes after fibrinolytic administration. METHODS: The goal was to develop a simple, broadly applicable angiographic metric that takes into account indices of epicardial and myocardial perfusion both before and after PCI to arrive at a single perfusion grade in patients undergoing cardiac catheterization after fibrinolysis. The angiographic perfusion score (APS) is the sum of the Thrombolysis in Myocardial Infarction (TIMI) flow grade (TFG; 0-3) added to the TIMI myocardial perfusion grade (TMPG; 0-3) before and after PCI (total possible grade, 0-12). Failed perfusion was defined as an APS of 0 to 3, partial perfusion was defined as an APS of 4 to 9, and full perfusion was defined as an APS of 10 to 12. The APS was evaluated in patients from the Double-blind, Placebo-contolled, Multicenter Angiographic Trial of Rhumab CD18 in Acute Myocardial Infarction (LIMIT-AMI; n = 394) and Enoxaparin as Adjunctive Antithrombin Therapy for ST-Elevation Myocardial Infarction-Thrombolysis In Myocardial Infarction (ENTIRE-TIMI) 23 trials (n = 483), and infarct size (120-216 hours after AMI SPECT Technetium-99m Sestamibi data) was assessed in the LIMIT-AMI trial. RESULTS: The APS was associated with the incidence of death or myocardial infarction (failed, 16.7% [n = 18]; partial, 2.5% [n = 155]; full, 2.4% [n = 82]; P =.039 for trend) and larger SPECT infarct sizes (failed, median 39% [n = 10]; partial, 12% [n = 79]; and full, 8% [n = 35]; P =.002). No patient with full APS died, whereas the mortality rate was 11.1% in patients with a failed APS (P =.03). CONCLUSIONS: The APS combines grades of epicardial and tissue level perfusion before and after PCI or at the end of diagnostic cardiac catheterization to arrive at a single angiographic variable that is associated with infarct size and the rates of 30-day death or MI. Partial or full angiographic perfusion scores are associated with a halving of infarct size, and no patients with full angiographic perfusion died.
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