Prognostic value of exercise gamma-angiography in coronary insufficiency

The predictive value for cardiac events in stable coronary artery disease was analysed with resting and exercise radionuclide angiography and conventional exercise stress testing under medical therapy. The population comprised 93 men and 12 women, followed up for 1 to 8 years (mean 51 months). The patients were divided into two groups. Group I without cardiac events; Group II including spontaneous complications and myocardial revascularisations. The analysis was performed at 2 years and at the end of follow-up. At 2 years, 30 events (15 spontaneous complications, 15 revascularisations) were observed, and at the end of follow-up, there were 61 uncomplicated outcomes and 44 cardiac events (22 spontaneous complications, 22 revascularisations). Two independent prognostic factors distinguishing patients in Group I from those in Group II were identified at 2 years and at the end of the study: exercise EF and occurrence of exercise (on: chest pain on exercise) chest pain. Four parameters were significantly different between the two groups at 2 years: exercise EF, resting EF, difference between exercise-resting EF (all p < 0.005) and duration of exercise testing (p = 0.04). The 3 radionuclide parameters remained different between the 2 groups as well as chest pain on exercise stress testing (p = 0.03) throughout the study. The predictive value of these parameters depended on the type of cardiac event. The exercise EF was the best predictive factor of cardiac death. Pain and ST depression on exercise ECG were the best predictive factors for myocardial revascularisation. In 12 patients undergoing myocardial revascularisation, the clearest improvement was observed in exercise EF (p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic value of myocardial hypoperfusion indexes in patients with suspected or known coronary artery disease

BACKGROUND: We evaluated the prognostic value of exercise 201Tl indexes of myocardial hypoperfusion in patients with suspected or known coronary artery disease. METHODS AND RESULTS: Patients were divided into two groups: group I consisted of 332 patients with diagnostic electrocardiographic stress test results and group II consisted of 144 patients with nondiagnostic (inadequate or uninterpretable) stress electrocardiograms. At the 2-year follow-up, 20 hard events (16 cardiac deaths and 4 nonfatal myocardial infarctions) and 80 soft events (coronary revascularization procedures) occurred in group I. Considering total events, thallium imaging provided significant prognostic information in addition to clinical and exercise stress test data in the total study population (p < 0.001) and in patients with previous myocardial infarction (p < 0.001); in patients without previous infarction, thallium imaging added incremental prognostic value only in those with positive electrocardiographic stress test results (p < 0.01). When only hard events were considered, thallium variables added further information only in patients with previous myocardial infarction (p < 0.05). In group II at the end of follow-up, 15 hard and 39 soft events had occurred. In these patients occurrence of total (p < 0.001), hard (p < 0.05), and soft (p < 0.001) events was higher in those with abnormal thallium scintigraphic results than in those without. Moreover, no clinical and exercise variable, except history of myocardial infarction, was significantly related to outcome, whereas both indexes of extent and severity of hypoperfusion were significant. CONCLUSIONS: The results of this study demonstrate that scintigraphic indexes of myocardial hypoperfusion obtained by qualitative planar thallium imaging give unique prognostic information in patients with nondiagnostic electrocardiographic stress test results. Thallium imaging provides incremental prognostic information even in patients with diagnostic electrocardiographic stress test results but not in the low-risk subset of patients without previous infarction who have negative electrocardiographic stress test results.     

Impairment of exercise capacity and peak oxygen consumption in patients with mild left ventricular dysfunction and coronary artery disease

AIMS: Most studies in chronic heart failure have only included patients with marked left ventricular systolic dysfunction (i.e. ejection fraction < or =0.35), and patients with mild left ventricular dysfunction are usually excluded. Further, exercise capacity strongly depends on age, but age-adjustment is usually not applied in these studies. Therefore, this study sought to establish whether (age-adjusted) peak VO2 was impaired in patients with mild left ventricular dysfunction. METHODS: Peak VO2 and ventilatory anaerobic threshold were measured in 56 male patients with mild left ventricular dysfunction (ejection fraction 0.35-0.55; study population) and in 17 male patients with a normal left ventricular function (ejection fraction >0.55; control population). All patients had an old (>4 weeks) myocardial infarction. By using age-adjusted peak VO2 values, a 'decreased' exercise capacity was defined as < or = predicted peak VO2 - 1 x SD (0.81 of predicted peak VO2), and a severely decreased exercise capacity as < or = predicted peak VO2 - 2 x SD (0.62 of predicted peak VO2). RESULTS: Patients in the study population (age 52+/-9 years; ejection fraction 0.46+/-0.06) were mostly asymptomatic (NYHA class I: n=40, 76%), while 16 patients (24%) had mild symptoms, i.e. NYHA class II. All 17 controls (age 57+/-8 years) were asymptomatic. Mean peak VO2 was lower in patients with mild left ventricular dysfunction (23.6+/-5.7 vs 27.1+/-4.6 ml x min(-1) x kg(-1) in controls, P<0.05). In 75% of the study population patients (n=42) age-adjusted peak VO2 was decreased (NYHA I/II: n=29/13) and in 18% of them severely decreased (n=10; NYHA I/II: n=6/4). In contrast, only three patients (18%) in the control population had a decreased and none a severely decreased age-adjusted peak VO2. CONCLUSION: In patients with mild left ventricular dysfunction, who have either no or only mild symptoms of chronic heart failure, a substantial proportion has an impaired exercise capacity. By using age-adjustment, impairment of exercise capacity becomes more evident in younger patients. Patients with mild left ventricular dysfunction are probably under-diagnosed, and this finding has clinical and therapeutic implications.     

Improved outcome after coronary bypass surgery in patients with ischemic cardiomyopathy and residual myocardial viability

BACKGROUND: Although residual myocardial viability in patients with coronary artery disease and extensive regional asynergy is associated with improved ventricular function after coronary bypass surgery, the relationship between viability and clinical outcome after surgery is unclear. We hypothesized that patients with poor ventricular function and predominantly viable myocardium have a better outcome after bypass surgery compared with those with less viability. METHODS AND RESULTS: Seventy patients with multivessel coronary artery disease and left ventricular ejection fractions < 40% who underwent preoperative quantitative 201Tl scintigraphy before coronary bypass surgery were analyzed retrospectively. 201Tl scintigrams were reviewed blindly, and each segment was assigned a score based on defect magnitude. Segmental viability scores were summed and divided by the number of segments visualized to determine a viability index. The viability index was significantly related to 3-year survival free of cardiac event (cardiac death or heart transplant) after bypass surgery (P=.011) and was independent of age, ejection fraction, and number of diseased coronary vessels. Patients with greater viability (group 1; viability index > 0.67; n=33) were similar to patients with less viability (group 2; viability index < or = 0.67; n=37) with respect to age, comorbidities, and extent of coronary artery disease. There were 6 cardiac deaths and no heart transplants in group 1 patients and 15 cardiac deaths and two transplants in group 2 patients. Survival free of cardiac death or transplantation was significantly better in group 1 patients on Kaplan-Meier analysis (P=.018). CONCLUSIONS: We conclude that resting 201Tl scintigraphy may be useful in preoperative risk stratification for identification of patients more likely to benefit from surgical revascularization.     

Revascularization in patients with prior coronary bypass surgery

Increasingly over the past several years, patients have returned after coronary surgery for reintervention procedures. This reflects immediate postsurgical complications and the relentless progression of coronary artery disease in the native circulation and in the bypass grafts. Although there are randomized comparative data for coronary bypass surgery (CABG) versus percutaneous transluminal coronary angioplasty (PTCA) and medical therapy, these trials have always excluded patients with previous (GABG). OBJECTIVES: We attempted to compare the risks and benefits of percutaneous transluminal coronary angioplasty (PTCA) and repeat coronary artery bypass grafting (re-CABG) in patients with previous coronary bypass surgery (CABG). METHODS AND RESULTS: This study examines follow up data (15.4 +/- 11.0 months) from 130 patients with previous CABG, who required either PTCA (Group A, n = 73) or re-CABG (Group B; n = 57) at a single center from 1994 to 1997. Follow up data were obtained from subsequent office visits and telephone calls. The PTCA and re-CABG groups were similar with respect to gender (86% vs 94% males), mean age (62 +/- 9 vs 59 +/- 10 years), angina CCS classes 3 and 4 (73% vs 69%), diminished left ventricular function (23% vs 26%), risk factors such as diabetes (19% vs 17%), hypercolesterolemia (49% vs 45%) and smoking (48% vs 39%) and three-vessel native coronary artery disease (67% vs 72%). The symptomatic status prior to the revascularization procedure was similar in both groups. Complete and functional revascularization was achieved in 85% of the PTCA group and in 92% of those with re-CABG (p = NS). During the hospital stay the complication rates were lower in the PTCA group. Actuarial survival was different at follow up (p = 0.04). Both PTCA and re-CABG groups resulted in equivalent event-free survival (freedom from death, myocardial infarction, unstable angina and urgent revascularization). The need for repeat revascularization at follow up was significantly higher in the PTCA group (PTCA 28% vs re-CABG 10%, p < 0.01). CONCLUSIONS: In this non-randomized study of patients with previous CABG requiring revascularization procedures, PTCA resulted in lower procedural morbidity and mortality risks. At follow up, both PTCA or CABG were similar for event-free survival; PTCA offered lower overall mortality, although it is associated to a greater need for subsequent revascularization procedures.     

Acute myocardial infarction in patients who have had coronary artery bypass surgery

BACKGROUND: Although acute myocardial infarction (AMI) and coronary artery bypass grafting (CABG) are frequently discussed, the issue of AMI in patients who have previously had CABG has not been addressed yet. METHODS: We critically reviewed data obtained from the medical literature on this subject since 1974. RESULTS: The overall incidence of AMI is about 10% during the first 3 years after CABG, though it occurs more frequently in older male patients. It seems that the infarct size is smaller and post-AMI ejection fraction is higher in patients who have had CABG than in those who have not. Although early mortality appears to be lower, on 5-year follow-up, more patients had AMI, angina, and revascularization procedures. CONCLUSIONS: The data abstracted indicate that AMI after CABG appears to be a well-delineated entity. Further studies are necessary to determine the optimal treatment for this population.     

Prognostic value of myocardial perfusion imaging with exercise and/or dipyridamole hyperemia in patients with preexisting left bundle branch block

OBJECTIVE: We describe the sudden onset of obsessive-compulsive symptoms following a peritoneal infection with alpha-haemolytic streptococci. CLINICAL PICTURE: A 35-year-old woman with no past history or family history of obsessions or compulsions developed these symptoms 2 weeks after a peritoneal infection. TREATMENT: The patient received 80 mg fluoxetine daily. OUTCOME: She responded to treatment with a progressive reduction in symptoms. CONCLUSIONS: It is suggested that these obsessions and compulsions may be related to an autoimmune response to the streptococcal infection.     

Outcome of coronary bypass surgery versus coronary angioplasty in diabetic patients with multivessel coronary artery disease

The coloration of cells of the cyanobacterium Synechococcus sp. PCC 7002 changed from normal blue-green to yellow-green when cells were grown at 15 degrees C in a medium containing nitrate as the sole nitrogen source. This change of coloration was similar to a general response to nutrient deprivation (chlorosis). For the chlorotic cells at 15 degrees C, the total amounts of phycobiliproteins and chlorophyll a decreased, high levels of glycogen accumulated, and growth was arithmetic rather than exponential. These changes in composition and growth occurred in cells grown at low (50 microE m-2 s-1) as well as high (250 microE m-2 s-1) light intensity. After a temperature shift-up to 38 degrees C, chlorotic cells rapidly regained their normal blue-green coloration and normal exponential growth rate within 7 h. When cells were grown at 15 degrees C in a medium containing urea as the reduced nitrogen source, cells grew exponentially and the symptoms of chlorosis were not observed. The decrease in photosynthetic oxygen evolution activity at low temperature was much smaller than the decrease in growth rate for cells grown on nitrate as the nitrogen source. These studies demonstrate that low-temperature-induced chlorosis of Synechococcus sp. PCC 7002 is caused by nitrogen limitation and is not the result of limited photosynthetic activity or photodamage to the photosynthetic apparatus, and that nitrogen assimilation is an important aspect of the low-temperature physiology of cyanobacteria.     

Mortality and morbidity after coronary bypass surgery in high-risk patients

A total of 113 women and 912 men were submitted to coronary artery bypass surgery at Surgical Department A, Rikshospitalet between August 1982 and December 1986 and followed till January 1993. We found no difference in early mortality, recurrent angina pectoris or non-fatal myocardial infarction in diabetic patients compared to nondiabetic patients. However, total mortality was 1.87 times higher in the diabetic group. For patients with ejection fraction < or = 40%, early mortality was 10.2 times higher than for the reference group. For total mortality we found a practically linear relationship between increased mortality and falling ejection fraction values. We found no relationship between ejection fraction and recurrent angina and non-fatal myocardial infarction, neither did we find any difference in mortality and morbidity between women and men. Although a somewhat higher mortality and morbidity rate must be expected for high-risk patients, they seem to profit to the same extent from the favourable effects of coronary bypass surgery as other patients.     

Prognostic value of vasodilator myocardial perfusion imaging in patients with left bundle-branch block

BACKGROUND: The prognostic value of tomographic myocardial perfusion imaging with dipyridamole or adenosine in patients with left bundle-branch block has not been established. METHODS AND RESULTS: The study group consisted of 245 patients with left bundle-branch block who underwent tomographic (single photon emission tomography) myocardial perfusion imaging with thallium-201 (n=173) or technetium-99m sestamibi (n=72) and either dipyridamole (n=153) or adenosine (n=92) stress. Patients were prospectively classified into two groups. Patients were classified as "high risk" if they had (1) a large severe fixed defect (n=28), (2) a large reversible defect (n=36), or (3) cardiac enlargement and either increased pulmonary uptake (thallium) or a decreased resting ejection fraction (sestamibi) (n=20). The remaining 161 patients (66% of the study group) were at "low risk." Follow-up was 99% complete at 3+/-1.4 years. Three-year overall survival was 57% in the high-risk group compared with 87% in the low-risk group (P<.0001). Survival free of cardiac death/nonfatal myocardial infarction/cardiac transplantation was 55% in the high-risk group and 93% in the low-risk group (P<.0001). The presence of a high-risk scan had significant incremental prognostic value after adjustment for age, sex, diabetes, and previous myocardial infarction (P<.0001). Patients with a low-risk scan had an overall survival that was not significantly different from that of a US age-matched population (P=.86). CONCLUSIONS: Tomographic myocardial perfusion imaging with adenosine or dipyridamole stress provides important prognostic information in patients with left bundle-branch block, which is incremental to clinical assessment.     

Aprotinin in patients having coronary artery bypass graft surgery

Any therapy must have a benefit and a risk. The benefit of aprotinin therapy in reducing bleeding is well known. Data presented over the past 12 months have confirmed this efficacy and the superiority and consistency of aprotinin therapy in direct comparison with other pharmacologic (desmopressin, tranexamic acid) and physical (administration of fresh platelet concentrate) interventions. The debate has now changed to focus on issues of the safety of this agent. In particular, concerns have been expressed as to the effect of this agent on renal function, thrombotic potential (and thus graft patency), and adverse reactions on a second exposure. Most recent reports show plasma creatinine concentrations are higher in treated than in nontreated patients on the 3rd or 4th postoperative day. The concentrations reached were not outside the clinical range, and there were no clinical sequelae of this biochemical abnormality. Focused studies have shown no effect of the use of aprotinin therapy on early graft patency or the incidence of thromboembolic complications. The reporting of hypersensitivity reactions following aprotinin administration suggests that the incidence is not different to other agents used in open heart surgery. Three reports of fatal or near-fatal cardiovascular collapse associated with the use of aprotinin followed the apparently inappropriate administration of the agent.     

Coronary angioplasty versus repeat coronary artery bypass grafting for patients with previous bypass surgery

OBJECTIVES: We attempted to determine the relative risks and benefits of percutaneous transluminal coronary angioplasty (PTCA) and repeat coronary artery bypass grafting (re-CABG) in patients with previous coronary bypass surgery (CABG). BACKGROUND: Due to an expanding population of patients with surgically treated coronary artery disease and the natural progression of atherosclerosis, an increasing number of patients with previous CABG require repeat revascularization procedures. Although there are randomized comparative data for CABG versus medical therapy and, more recently, versus PTCA, these studies have excluded patients with previous CABG. METHODS: We retrospectively analyzed data from 632 patients with previous CABG who required either elective re-CABG (n = 164) or PTCA (n = 468) at a single center during 1987 through 1988. The PTCA and re-CABG groups were similar with respect to gender (83% vs. 85% male), age > 70 years (21% vs. 23%), mean left ventricular ejection fraction (46% vs. 48%), presence of class III or IV angina (70% vs. 63%) and three-vessel coronary artery disease (77% vs. 74%). RESULTS: Complete revascularization was achieved in 38% of patients with PTCA and 92% of those with re-CABG (p < 0.0001). The in-hospital complication rates were significantly lower in the PTCA group: death (0.3% vs. 7.3%, p < 0.0001) and Q wave myocardial infarction (MI) (0.9% vs. 6.1%, p < 0.0001). Actuarial survival was equivalent at 1 year (PTCA 95% vs. re-CABG 91%) and 6 years (PTCA 74% vs. re-CABG 73%) of follow-up (p = 0.32). Both procedures resulted in equivalent event-free survival (freedom from dealth or Q wave MI) and relief of angina; however, the need for repeat percutaneous or surgical revascularization, or both, by 6 years was significantly higher in the PTCA group (PTCA 64% vs. re-CABG 8%, p < 0.0001). Multivariate analysis identified age > 70 years, left ventricular ejection fraction < 40%, unstable angina, number of diseased vessels and diabetes mellitus as independent correlates of mortality for the entire group. CONCLUSIONS: In this nonrandomized series of patients with previous CABG requiring revascularization, an initial stategy of either PTCA or re-CABG resulted in equivalent overall survival, event-free survival and relief of angina. PTCA offers lower procedural morbidity and mortality risks, although it is associated with less complete revascularization and a greater need for subsequent revascularization procedures.     

Variations of cardiac cycle length in patients with coronary heart disease before and after aortic coronary bypass surgery

It is well known that variations in cardiac cycle length or heart rates may be used for noninvasive evaluation of autonomic cardiovascular control. The investigation uses an original procedure. The data for analysis of cardiac cycle length variations (CCLV) are those obtained regularly at follow-up intervals, random 24-hour Holter 2-lead ECG recordings for 5 sec, and simultaneously calculated continuous sequence of mean heart rate. With the procedure, the correlations of CCLV with the parameters reflecting the early postoperative status of patients with CHD, including acute myocardial infarction, acute heart failure, rhythm and conduction disturbances, as well as age, operative stress, concurrent diseases. The findings are of both diagnostic and predictive value at subsequent stages of CHD treatment.     

Postoperative arrhythmias and myocardial electrolytes in patients undergoing coronary artery bypass grafting

Electrolyte changes in right atrial and skeletal muscle pre- intra- and postoperatively, and their relationship to the development of postoperative atrial fibrillation or flutter were evaluated in 31 patients with coronary artery bypass grafting (CABG). Such postoperative arrhythmias occurred in 14 patients (45%). Before CABG the skeletal muscle potassium concentration was lower in these patients than in the others: median 261.4 (range 148.2-329.5) vs 298.6 (167.1-416.4) mumol/g dry weight, p = 0.017. The right atrial potassium concentration was normal, but sodium levels were higher in the patients with, than in those without postoperative arrhythmias: median 340.3 (263.7-454.9) vs 296.3 (203.9-355.0) mumol/g dry weight, p = 0.008, indicating disturbed transmembrane electrolyte transfer. During CABG the potassium levels fell and sodium increased in both right atrium and skeletal muscle, and on postoperative day 2 the potassium content in skeletal muscle was not yet restored. Magnesium levels showed no changes in right atrium or skeletal muscle, but serum magnesium declined postoperatively. As the observed electrolyte derangements may be important in the development of postoperative arrhythmias, concomitant potassium and magnesium supplement postoperatively may be beneficial in restoring cellular potassium concentration.     

Thrombogenic and atherogenic lipid modifications in plasma and patients with coronary artery disease and after coronary artery bypass surgery

BACKGROUND: Although multiple studies have shown that the left ventricular assist device (LVAD) improves distorted cardiac geometry, the pathological mechanisms of the "reverse remodeling" of the heart are unknown. Our goal was to determine the effects of LVAD support on cardiac myocyte size and shape. METHODS AND RESULTS: Isolated myocytes were obtained at cardiac transplantation from 30 failing hearts (12 ischemic, 18 nonischemic) without LVAD support, 10 failing hearts that received LVAD support for 75+/-15 days, and 6 nonfailing hearts. Cardiac myocyte volume, length, width, and thickness were determined by use of previously validated techniques. Isolated myocytes from myopathic hearts exhibited increased volume, length, width, and length-to-thickness ratio compared with normal myocytes (P<0.05). However, there were no differences in any parameter between myocytes from ischemic and nonischemic cardiomyopathic hearts. Long-term LVAD support resulted in a 28% reduction in myocyte volume, 20% reduction in cell length, 20% reduction in cell width, and 32% reduction in cell length-to-thickness ratio (P<0.05). In contrast, LVAD support was associated with no change in cell thickness. These cellular changes were associated with reductions in left ventricular dilation and left ventricular mass measured echocardiographically in 6 of 10 LVAD-supported patients. CONCLUSIONS: These studies suggest that the regression of cellular hypertrophy is a major contributor to the "reverse remodeling" of the heart after LVAD implantation. The favorable alterations in geometry that occur in parallel fashion at both the organ and cellular levels may contribute to reduced wall stress and improved mechanical performance after LVAD support.     

Predictors of long-term change in functional status after coronary artery bypass graft surgery in women

A cohort of 164 women who had undergone coronary artery bypass graft surgery (CABG) was followed for one year to examine changes in functional status and determine the relative influence of clinical, psychosocial and sociodemographic factors on change in functional status outcomes between 6 and 12 months after surgery. Clinical, psychosocial, sociodemographic and preoperative functional status data were collected by written questionnaire and personal interview at the time of surgery and again at 6 and 12 months after CABG. Functional status scores improved significantly from before to 6 months after CABG. Between 6 and 12 months post-CABG 65% sustained or continued to experience improvement in physical functioning, 83% in social and leisure activities, and 54% in psychological functioning. Predictors of sustained improvement in physical functioning were being married, younger age, low 6-month functioning, having an ejection fraction of 50% or greater, and being white. The significant predictors of sustained improvement in social and leisure activities and psychological functioning were being married and low 6-month psychological functioning, respectively. These data suggest that interventions to improve long-term outcomes in women undergoing CABG should take into account not only their age, functional capacity and level of functioning at 6 months post-CABG, but also their race and marital status as potential risk factors for long-term functional status disability.     

Effect of percutaneous transluminal coronary angioplasty on exercise in patients with and without previous myocardial infarction

Improvement in exercise capacity is an important clinical effect of percutaneous transluminal coronary angioplasty (PTCA), and was assessed in patients with and without previous myocardial infarction (MI) undergoing PTCA. We prospectively followed patients with exercise testing before and 2 weeks after angioplasty in 415 patients, 170 (41%) of whom had a previous MI. A third exercise test was performed 20 +/- 2 weeks after PTCA in 403 patients. From left ventricular angiography obtained before PTCA, regional dyskinesia was classified into anterior or posterior locations. Both patients with and without previous MI had a significant increase in exercise capacity from before to 2 and 20 weeks after PTCA (previous MI: 31.9% and 29.3%; no MI: 50.7% and 38.2%; p <0.0001 [analysis of variance]). In patients with MI and anterior dyskinesia, in whom lesions on the left anterior descending artery were dilated or posterior dyskinesia in whom lesions on the right coronary artery were dilated, exercise capacity increased significantly from before to 2 and 20 weeks after PTCA (left anterior descending artery: 53.1% and 39.7%, p <0.0001; right coronary artery: 16.9% and 27.6%, p = 0.01 [analysis of variance]). Multivariate regression analysis revealed that male sex, no previous MI, and dilation of left anterior descending artery were significantly associated with increased exercise capacity after angioplasty adjusted for age and smoking habits, whereas left ventricular ejection fraction and end-diastolic pressure were not associated with increased exercise capacity.     

Correct utilization of exercise electrocardiographic leads in differentiation of men with coronary artery disease from patients with a low likelihood of coronary artery disease using peak exercise ST-segment depression

In this study we compared the diagnostic characteristics of the individual exercise electrocardiographic leads, 3 different lead sets comprising standard leads and the effect of the partition value in the detection of coronary artery disease (CAD). The diagnostic variable used was ST-segment depression at peak exercise, and the study population consisted of 101 patients with CAD and 100 patients with a low likelihood of the disease. The lead system used was the Mason-Likar modification of the standard 12-lead system and exercise tests were performed on a bicycle ergometer. The comparisons were performed by means of receiver-operating characteristic analysis and by determining sensitivities at a fixed 95% specificity. These properties, defined here as diagnostic capacity, were the most efficacious in leads I, -aVR, V4, V5, and V6. Diagnostic capacities in leads aVL, aVF, III, V1, and V2 were quite poor; statistical comparisons indicated significant differences between these leads and lead V5 (p < or = 0.0001 in each case). Use of the maximum value of ST-segment depression at peak exercise derived from all 12 leads produced a considerable decrease in the diagnostic capacity of the exercise electrocardiogram compared with lead V5. The exclusion of leads aVL, V1, and III improved the diagnostic capacity compared with the 12-lead set, but it was still smaller than that of lead V5. With use of a lead set with the 5 best leads increased the diagnostic capacity over other lead sets and over any individual lead. Further improvement was noted when a 50% smaller partition value was applied to leads I and -aVR than for the other leads (p = 0.041). In conclusion, this study suggests that use of leads I, -aVR, V4, V5, and V6 is the most influential when differentiating between patients with CAD and patients with a low likelihood of disease using peak exercise ST-segment depression. The effective use of leads I and -aVR requires the partition value applied for these leads to be 50% smaller than that used for the lateral precordial leads.