The significance of exercise-induced Q waves.

The significance of transient exercise-induced Q waves present during treadmill testing was prospectively evaluated and correlated with the findings at cardiac catheterization. Exercise-induced Q waves were present in 14 of 560 patients (2.5 per cent) undergoing treadmill exercise testing. Thirteen patients had Q waves in leads V1 through V3 and one patient had Q waves in leads II, III and aVF. Ten patients underwent cardiac catheterization; six did not have coronary artery disease as determined by angiography. Two patients had a documented anterior myocardial infarction and did not undergo cardiac catheterization. Exercise myocardial perfusion imaging was performed in 10 patients. Six patients without coronary artery disease had no evidence of exercise perfusion defects. In the four patients with coronary artery disease, three patients had an abnormal resting perfusion study without change with exercise and one patient had a new exercise myocardial perfusion defect. We conclude that exercise-induced transient Q waves are not diagnostic of underlying coronary disease. In patients without coronary artery disease the mechanism of exercise-induced Q waves is as yet unclear. In patients with coronary artery disease, the mechanism may also be undefined or secondary to myocardial ischemia.     

Post-myocardial infarction exercise testing. Non-Q wave versus Q wave correlation with coronary angiography and long-term prognosis

BACKGROUND. The presence or absence of baseline diagnostic Q waves has been believed to compromise the accuracy of standard exercise electrocardiography in identifying severe coronary artery disease (three-vessel and/or left main disease); therefore, a retrospective analysis was performed using a personal computer data base of exercise test responses and cardiac catheterization results to evaluate this premise, and follow-up was performed to observe how Q waves and/or severe coronary disease impacted on survival. METHODS AND RESULTS. Two hundred fifty-three male patients who had survived a myocardial infarction were studied. Patients on digitalis, those with left bundle branch block or left ventricular hypertrophy on their baseline electrocardiogram, those with previous revascularization procedures, and those with significant valvular or congenital heart disease were excluded. All patients performed either a low-level predischarge or a sign/symptom limited exercise test and underwent diagnostic coronary angiography within 32 days of each test (range, 0-90 days). Long-term follow-up on patients was performed for an average of 45 months (+/- 17 months). Group NQMI comprised 103 post-myocardial infarction patients lacking Q waves at the time of exercise testing and group QMI comprised 150 patients who developed Q waves with their myocardial infarction. The cut points of greater than or equal to 1 mm (chi 2 = 14.39, p less than 0.001) and greater than or equal to 2 mm (chi 2 = 26.11, p less than 0.001) of exercise-induced ST segment depression were reliable markers of severe coronary disease in Q wave infarct survivors. This was also true for non-Q wave infarct survivors as greater than or equal to 1 mm (chi 2 = 6.02, p = 0.01) and greater than or equal to 2 mm (chi 2 = 4.37, p = 0.04) of ST segment depression were reliable markers of severe coronary disease. Receiver operating characteristic curve analysis revealed that exercise-induced ST segment depression had discriminating power for the identification of severe coronary artery disease in both the Q wave myocardial infarction patients (area = 0.735, z = 4.47, p less than 0.001) and the non-Q wave infarct patients (area = 0.700, z = 3.20, p less than 0.001). After 4.4 years of cumulative follow-up, patients with severe coronary disease had an infarct-free survival rate of 72% (95%, CI, 50.0-86.0%), whereas those without severe disease had an 86% (95% CI, 76.5-91.5%) infarct-free survival rate (Cox chi 2 = 4.00, p = 0.045). Non-Q wave patients had an infarct-free survival rate of 81% (95% CI, 66.0-89.5%), whereas those with Q waves had an infarct-free survival rate of 85% (95% CI, 73.9-91.3%) (Cox chi 2 = 0.0005, p = NS). CONCLUSIONS. The presence or absence of diagnostic Q waves has no significant effect on the ability of the exercise electrocardiogram to identify severe coronary artery disease in survivors of myocardial infarction. Long-term infarct-free survival of patients with myocardial infarction is more related to the presence of severe coronary disease rather than if they suffered a non-Q wave or Q wave infarction.     

Early treadmill testing after myocardial infarction: Angiographic and hemodynamic correlations.

Twenty-eight patients who were two weeks post acute myocardial infarction walked on a motorized treadmill at 1 MPH 0 percent grade for five minutes (group 1) or to an end-point of symptoms, ST-T wave changes or arrhythmias (group 2). At subsequent cardiac catheterization, 73 percent in group 1 had single vessel coronary artery disease whereas 82 percent group 2 had three or four vessel coronary artery disease. Ejection fraction was better in group 1 as was the slope of a modified left ventricular function curve. We conclude that limited exercise treadmill testing soon after acute myocardial infarction may be useful in predicting the extent of coronary artery disease and the amount of left ventricular dysfunction.     

Prognostic value of the exercise test in patients with ischemic heart disease

The objective of this study is to determine the prognostic value of stress testing in patients with coronary heart disease. We examined 95 cases followed during an average period of 33 months. The age was 52 +/- 9 years. All patients had clinical evidence of myocardial ischemia: 78 had previous myocardial infarction, 11 stable angor pectoris and six unstable angina. After the initial event 33 patients were asymptomatic and 62 with mild angina. During follow-up; 42 patients had no coronary events; 10 died, six developed non-fatal myocardial infarction and 37 had more angina, nine of these patients were treated with bypass coronary artery surgery. The annual mortality was 3.8%, all with previous myocardial infarction. In the stress testing the patients who died were distinguished by limited exercise ability and severe changes of ST-T segment. Patients with greater than or equal to 0.2 mV ST-T segment depth or effort duration less than or equal to 3 minutes had an annual mortality F 7% 13.6% respectively.     

The prognostic value of a QRS score during exercise testing

BACKGROUND: Values of a QRS score have been positively related to the number of narrowed coronary arteries and to the extent of myocardial ischemia in radionuclide imaging techniques. HYPOTHESIS: This study was conducted to evaluate the potential prognostic information of abnormal values of this QRS score during treadmill exercise testing in patients with established coronary artery disease (CAD). METHODS: In all, 309 patients (258 men, 51 women, mean age 56.1 +/- 10.0 years) with documented CAD, underwent a treadmill exercise test and coronary arteriography at baseline. Subsequently, they were prospectively followed to a maximum of 36 months (mean follow-up 23 +/- 13 months, median 25 months). RESULTS: During the follow-up period, 20 patients (6.5%) died from acute myocardial infarction. Abnormal QRS score values were found to be significantly and independently associated with cardiac mortality (QRS < or = -4: relative risk 11.7; 95% confidence interval = 2.5-55.4; p = 0.002). CONCLUSIONS: Taking into consideration the importance of exercise testing in the management of ischemic heart disease, the use of this QRS score could be of clinical value in predicting the outcome of patients with documented CAD.     

Changes of Q wave amplitude during exercise for the prediction of coronary artery disease

We have examined the changes of Q wave amplitude during exercise in 156 patients with chest pain with a view to improving the accuracy of stress testing for the diagnosis of coronary artery disease. Coronary arteriography showed significant disease in 127 patients and normal arteries or minimal disease in 29. The Q wave amplitude was measured in lead CM5 from the computer-derived average of 25 consecutive beats immediately before and at the peak of maximal treadmill exercise. The amplitude was greater in the normal subjects at rest and increased with exercise, but the reverse occurred in those with coronary disease. Using the criterion of decrease or no change of Q wave amplitude during exercise as indicating a positive test, the discriminative capacity of Q wave changes was equivalent to that of ST segment depression and was maintained when patients with myocardial infarction were excluded. Using either an abnormal Q wave or ST segment response to exercise improved the test's sensitivity with a loss of specificity but no change of predictive value. In 42% of patients with coronary disease when both the Q wave and ST segment exercise responses were abnormal coronary disease was predicted with an accuracy of 91%. Analysis of subgroups of patients with coronary artery disease suggested a possible explanation for the observed changes in Q wave amplitude, measurement of which can improve the stress test's accuracy for predicting obstructive coronary artery disease.     

Usefulness of thallium-201 scintigraphy in predicting the development of angina pectoris in hypertensive patients with left ventricular hypertrophy

Hypertension and left ventricular (LV) hypertrophy are independent risk factors for the development of coronary artery disease. To determine whether patients at higher risk for coronary artery disease can be identified, 40 asymptomatic hypertensive men with LV hypertrophy were prospectively studied using exercise thallium-201 scintigraphy and exercise radionuclide angiography. Endpoints indicative of coronary artery disease were defined as the subsequent development of typical angina pectoris, which occurred in 8 patients during a median follow-up of 38 months, or myocardial infarction, which did not occur. The exercise electrocardiogram was interpreted by standard ST-segment criteria and by a computerized treadmill exercise score. Abnormal ST-segment responses were present in 16 of the 40 hypertensives (40%), whereas the treadmill score was positive in 8 of those same 40 patients (20%). Scintigraphic perfusion defects assessed both visually and semiquantitatively were observed in 8 of 40 (20%) patients. An abnormal ejection fraction response to exercise was present in 40% (16 of 40) of patients, and 3 of 40 (7.5%) developed new wall motion abnormalities during exercise. Six of 8 patients with either perfusion defects or abnormal treadmill score developed typical angina during follow-up. All 5 patients with concordant positive exercise scintigrams and treadmill score developed chest pain during follow-up and had coronary artery disease confirmed by coronary angiography. However, only 7 of 16 (44%) patients with positive ST changes or abnormal ejection fraction responses during exercise developed chest pain during follow-up. In contrast, of 32 patients with negative scintigrams only 2 developed atypical chest pain syndromes, and significant coronary artery disease was excluded by angiography in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)     

Positive treadmill stress tests post myocardial infarction in patients with single-vessel coronary disease

To investigate the possibility that patients with single-vessel coronary artery disease (CAD) and recent myocardial infarction (MI) can have ST segment depression on post infarction treadmill testing due to ischemia, we studied 16 such patients who underwent cardiac catheterization and exercise testing after MI. Of the 11 patients with ST segment depression on treadmill testing, 10 failed to increase their ejection fraction and nine had a focal worsening of wall motion during exercise radionuclide ventriculography. Seven of these 11 patients had hypokinesis or normokinesis in the suspected area of infarction. In contrast, four of the five patients without ST segment depression on treadmill stress testing had an increase in ejection fraction with stress which was significantly greater than that seen in patients with ST depression (7.2% vs 0%, p less than 0.05). Short-term follow-up (1.1 years) revealed continued post infarction angina in 10 of the 11 patients with positive treadmill stress tests. Four of these patients underwent either percutaneous transluminal angioplasty or surgery. We conclude that positive post infarction treadmill tests due to exercise-induced ischemia may occur in patients with single-vessel CAD and may be associated with continued angina that requires surgical intervention.     

Non Q wave infarction: exercise test characteristics, coronary anatomy, and prognosis

The exercise test characteristics, coronary anatomy, and prognosis of patients discharged after non Q wave myocardial infarction were compared with those in whom Q wave infarction occurred. Of the 339 patients studied, all of whom were less than or equal to 70 years, 87 (26%) had had a non Q wave infarction. There were no significant differences in the exercise test characteristics between the two groups, and in those 149 patients in whom angiography was performed triple vessel disease was present in 36/114 (32%) of the Q wave group and 9/35 (26%) of the non Q wave group. The infarct related artery was more often patent in the non Q wave group (27/35 (77%] than in the Q wave group (53/114 (46%]. The one year mortality and the reinfarction and angina rates were similar in the two groups and the exercise test remained a good discriminator for predicting patients at risk of future cardiac events in both groups. In view of the similar outcome and severity of coronary disease in those aged less than or equal to 70 with non Q wave infarcts, the distinction between Q and non Q wave infarction need not influence management decisions in patients after myocardial infarction.     

Use of radionuclide angiography and an electrocardiographic stress test to diagnose multivessel disease after a first episode of uncomplicated myocardial infarction

Sixty consecutive patients who were symptom free 2-12 months after an uncomplicated acute myocardial infarction underwent maximal treadmill exercise testing, radionuclide angiography before and during submaximal bicycle stress test, and coronary angiography. The results of the non-invasive procedures were compared with those of coronary angiography. The sensitivity and specificity of electrocardiogram stress test for detection of multivessel disease were 40% and 77% respectively. Failure of left ventricular ejection fraction to increase at least 5% with exercise identified 20 of the 25 patients with multivessel disease (sensitivity 80%) and 23 of the 35 patients with no additional coronary artery stenosis (specificity 66%). In patients with anterior Q waves the sensitivity was 78% and the specificity 50%, whereas in the presence of inferior Q waves these values were 81% and 87% respectively. Loss of left ventricle synchronicity during effort, as indicated by failure of the standard deviation of the phases to decrease during exercise, demonstrated a radionuclide angiography sensitivity of 80% (77% for anterior myocardial infarction and 81% for inferior myocardial infarction) and a specificity of 50% (33% for anterior myocardial infarction and 64% for inferior myocardial infarction). When the test was considered to be positive if either the ejection fraction or the standard deviation of the phases criteria were positive, the sensitivity was 100% and specificity 46% (30% for anterior myocardial infarction and 65% for inferior myocardial infarction). It is concluded that in patients who are free from angina 2-12 months after an episode of uncomplicated myocardial infarction, a simple exercise electrocardiogram cannot be relied upon to detect residual ischaemia. An abnormal ejection fraction response or an increased standard deviation of the phases during exercise nuclear angiography or both identified all the patients with multivessel disease. None of the patients in whom radionuclide angiographic criteria were negative had multivessel disease.     

Non Q wave infarction: exercise test characteristics, coronary anatomy, and prognosis.

The exercise test characteristics, coronary anatomy, and prognosis of patients discharged after non Q wave myocardial infarction were compared with those in whom Q wave infarction occurred. Of the 339 patients studied, all of whom were less than or equal to 70 years, 87 (26%) had had a non Q wave infarction. There were no significant differences in the exercise test characteristics between the two groups, and in those 149 patients in whom angiography was performed triple vessel disease was present in 36/114 (32%) of the Q wave group and 9/35 (26%) of the non Q wave group. The infarct related artery was more often patent in the non Q wave group (27/35 (77%] than in the Q wave group (53/114 (46%]. The one year mortality and the reinfarction and angina rates were similar in the two groups and the exercise test remained a good discriminator for predicting patients at risk of future cardiac events in both groups. In view of the similar outcome and severity of coronary disease in those aged less than or equal to 70 with non Q wave infarcts, the distinction between Q and non Q wave infarction need not influence management decisions in patients after myocardial infarction.     

Use of radionuclide angiography and an electrocardiographic stress test to diagnose multivessel disease after a first episode of uncomplicated myocardial infarction.

Sixty consecutive patients who were symptom free 2-12 months after an uncomplicated acute myocardial infarction underwent maximal treadmill exercise testing, radionuclide angiography before and during submaximal bicycle stress test, and coronary angiography. The results of the non-invasive procedures were compared with those of coronary angiography. The sensitivity and specificity of electrocardiogram stress test for detection of multivessel disease were 40% and 77% respectively. Failure of left ventricular ejection fraction to increase at least 5% with exercise identified 20 of the 25 patients with multivessel disease (sensitivity 80%) and 23 of the 35 patients with no additional coronary artery stenosis (specificity 66%). In patients with anterior Q waves the sensitivity was 78% and the specificity 50%, whereas in the presence of inferior Q waves these values were 81% and 87% respectively. Loss of left ventricle synchronicity during effort, as indicated by failure of the standard deviation of the phases to decrease during exercise, demonstrated a radionuclide angiography sensitivity of 80% (77% for anterior myocardial infarction and 81% for inferior myocardial infarction) and a specificity of 50% (33% for anterior myocardial infarction and 64% for inferior myocardial infarction). When the test was considered to be positive if either the ejection fraction or the standard deviation of the phases criteria were positive, the sensitivity was 100% and specificity 46% (30% for anterior myocardial infarction and 65% for inferior myocardial infarction). It is concluded that in patients who are free from angina 2-12 months after an episode of uncomplicated myocardial infarction, a simple exercise electrocardiogram cannot be relied upon to detect residual ischaemia. An abnormal ejection fraction response or an increased standard deviation of the phases during exercise nuclear angiography or both identified all the patients with multivessel disease. None of the patients in whom radionuclide angiographic criteria were negative had multivessel disease.     

Comparison of S-T segment changes on exercise testing with angiographic findings in patients with prior myocardial infarction

Ninety-seven patients with a prior transmural myocardial infarction who underwent coronary angiography and treadmill stress testing were studied retrospectively to assess the reliability of the exercise electrocardiogram in detecting additional disease in patients with a prior infarction. In patients with a previous inferior wall infarction, the S-T response to the treadmill stress test had a high degree of sensitivity (87 percent) and specificity (90 percent) in detecting additional significant coronary artery disease. However, in patients with a previous anteroseptal wall Infarction, the S-T response had much less sensitivity (52 percent), but the degree of specificity remained high (90 percent). In this group a positive test suggested the presence of ischemia in the lateral or inferoposterior region of the myocardium, or both. A negative S-T response was of little value In distingulshing among groups of patients with single or multiple vessel coronary artery disease. The presence of an anterior ventricular aneurysm is most likely responsible for this low sensitivity rate because it generates an opposing force to the ischemic vector, thereby cancelling the S-T segment changes and producing a false negative treadmill stress test. The resting surface electrocardiogram proved useful in predicting a false negative exercise test. The presence of Q waves in the precordial leads extending to lead V₄ or beyond decreased the sensltivity rate of treadmill stress testing to 33 percent.     

Two- to three-year follow-up of patients with single-vessel coronary artery disease randomized to PTCA or medical therapy (results of a VA cooperative study)

Despite increasing use of percutaneous transluminal coronary angioplasty (PTCA) to treat stenotic coronary artery disease, there are relatively few prospective studies evaluating its long-term effectiveness. We prospectively randomized 212 stable patients with provocable myocardial ischemia and single-vessel subocclusive coronary disease to receive primary therapy with either PTCA or medical therapy. This report presents the clinical follow-up of these patients at a mean, after randomization, of 2.4 years for interview and 3.0 years for exercise testing. Of the 212 patients originally randomized, 175 received an extended follow-up interview, and 132 underwent exercise testing; 62% of patients in the PTCA group were angina free compared with 47% of patients in the medical group (p <0.05). Furthermore, exercise duration as measured by treadmill testing was prolonged by 1.33 minutes over baseline in the PTCA group, whereas it decreased by 0.28 minutes in the medical group (p <0.04). Although the angina-free time on the treadmill was not different (p = 0.50), fewer patients in the medical group developed angina on the treadmill at 3 years than those in the PTCA group (p = 0.04). By 36 months, excluding the initial randomized PTCA, use of PTCA and use of coronary artery bypass surgery were not different in the 2 treatment groups. These data indicate that some of the early benefits derived from PTCA in patients with single-vessel coronary artery disease are sustained, making it an attractive therapeutic option for these patients.     

Comparison of silent and symptomatic ischemia during exercise testing in men

OBJECTIVE: To compare angina and ST-segment depression during exercise testing, as markers for coronary artery disease. DESIGN: Retrospective analysis of exercise test responses and cardiac catheterization results. SETTING: A U.S. Veterans Affairs medical center. PATIENTS: Four hundred and sixteen men who were referred for the evaluation of symptoms, postmyocardial infarction testing, or both. Two hundred patients had no clinical or electrocardiographic evidence of previous myocardial infarction, whereas 216 were survivors of a previous myocardial infarction. INTERVENTIONS: All patients did a standard exercise test and had diagnostic coronary angiography with ventriculography within an average of 32 days (range, 0 to 90 days) of their exercise test. RESULTS: Two hundred patients without a previous myocardial infarction were divided into four groups: the no ischemia group had 80 patients; the angina pectoris only group had 23 patients; the silent ischemia group had 40 patients; and the ST-segment depression and angina pectoris group had 57 patients. In patients without a previous myocardial infarction, exercise-induced ST-segment depression was a better marker than exercise-induced angina for the presence of any coronary artery disease (P less than 0.005). Patients with symptomatic exercise-induced ischemia had a higher prevalence of severe coronary artery disease than did those with only silent ischemia (30% compared with 20%; 95% CI, - 7.3% to 27.0%; P = 0.005). For the 216 survivors of a myocardial infarction, divided into the same four groups, ST-segment depression again was a better marker for the presence of severe coronary artery disease compared with angina alone (P = 0.08). The prevalence rates of severe coronary artery disease in the no ischemia plus myocardial infarction group, the angina pectoris only plus myocardial infarction group, the silent ischemia plus myocardial infarction group, and the ST-segment depression and angina pectoris plus myocardial infarction group were 10%, 9%, 23%, and 32%, respectively (P less than 0.01). CONCLUSIONS: Exercise-induced ST-segment depression is a better marker for coronary artery disease than is exercise-induced angina. Symptomatic ischemia during the exercise test is a better marker for severe coronary artery disease than is silent ischemia.     

Prognostic value of normal myocardial radionuclide scan in patients with positive treadmill test

The purpose of this study was to determine the prognostic value of a normal 201Tl scan in patients with a positive treadmill exercise stress test. We analyzed retrospectively 85 consecutive patients with a positive treadmill exercise test and normal Tl201 scan who were studied for the diagnosis of coronary artery disease from January 1996 to December 2000. The pretest probability of coronary artery disease was intermediate or high in all patients. Seventy-eight patients (89%) were followed up for 2.03 years. Forty patients (51%) were men. Age was 56 years. The cardiac events considered were angina, revascularization, nonfatal myocardial infarction, and cardiac death. During the follow-up period, none of the patients suffered a major cardiac event. Eight patients had episodes of chest pain and one had angor that required revascularization. Patients with an intermediate probability of coronary artery disease before the test and normal myocardial radionuclide scan had a very good prognosis even with a positive treadmill exercise test.     

Clinical and exercise test predictors of all-cause mortality: results from > 6,000 consecutive referred male patients

OBJECTIVE: To report the prevalence of abnormal treadmill test responses and their association with mortality in a large consecutive series of patients referred for standard exercise tests, with testing performed and reported in a standardized fashion. BACKGROUND: Exercise testing is widely performed, but few databases exist of large numbers of consecutive tests performed on patients referred for routine clinical purposes using standardized methods. Even fewer of the available databases have information regarding all-cause mortality as an outcome. METHODS: All patients referred for evaluation at two university-affiliated Veterans Affairs medical centers who underwent exercise treadmill testing for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security death index after a mean 6.2 years (median, 7 years) of follow-up. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. All-cause mortality was utilized as the end point for follow-up. Standard survival analysis was performed, including Kaplan-Meier curves and a Cox hazard model. RESULTS: There were 6,213 male patients (mean +/- SD age, 59 +/- 11 years) who underwent standard exercise ECG treadmill testing over the study period with a mean follow-up duration of 6.2 +/- 3.7 years. There were no complications of testing in this clinically referred population, 78% of whom were referred for chest pain, or risk factors or signs or symptoms of ischemic heart disease. Overlapping thirds had typical angina or history of myocardial infarction (MI). Five hundred seventy-nine patients had prior coronary artery bypass surgery, and 522 patients had a history of congestive heart failure (CHF). Indications for testing were in accordance with published guidelines. Twenty percent died over the follow-up period, for an average annual mortality rate of 2.6%. Cox hazard function chose the following variables in rank order as independently and significantly associated with time to death: exercise capacity (metabolic equivalents < 5, age > 65 years, history of CHF, and history of MI. A score based on these variables (summing up the four variables [if yes = 1 point]) classified patients into low-risk, medium-risk, and high-risk groups. The high-risk group (score > or = 3) has a hazard ratio of 5.0 (95% confidence interval, 4.7 to 5.3) and a 5-year mortality rate of 31%. CONCLUSION: This comprehensive analysis provides rates of various abnormal responses that can be expected in patients referred for exercise testing at a typical medical center. Four simple variables combined as a score powerfully stratified patients according to prognosis.     

Painless exercise ST deviation on the treadmill: long-term prognosis

To evaluate the clinical correlates and long-term prognostic significance of silent ischemia during exercise, 1,698 consecutive symptomatic patients with coronary artery disease who had both treadmill testing and cardiac catheterization were studied. These patients were classified into three groups: Group 1 = patients with no exercise ST deviation (n = 856), Group 2 = patients with painless exercise ST deviation (n = 242) and Group 3 = patients with both angina and ST segment deviation during exercise (n = 600). Patients with exercise angina had a history of a longer and more aggressive anginal course (with a greater frequency of angina, with nocturnal episodes and/or progressive symptom pattern) and more severe coronary artery disease (almost two-thirds had three vessel disease). The 5 year survival rate among the patients with painless ST deviation was similar to that of patients without ST deviation (86% and 88%, respectively) and was significantly better than that of patients with both symptoms and ST deviation (5 year survival rate 73% in patients with exercise-limiting angina). Similar trends were obtained in subgroups defined by the amount of coronary artery disease present. In the total study group of 1,698 patients, silent ischemia on the treadmill was not a benign finding (average annual mortality rate 2.8%) but, compared with symptomatic ischemia, did indicate a subgroup of patients with coronary artery disease who had a less aggressive anginal course, less coronary artery disease and a better prognosis. Thus, silent ischemia during exercise testing in patients with symptomatic coronary artery disease represents an intermediate risk response in the spectrum of exercise-induced ischemia.     

Exercise treadmill testing is a poor predictor of anatomic restenosis after angioplasty for acute myocardial infarction

This study evaluated whether an exercise treadmill test could predict restenosis in 289 patients 6 months after a successful emergency angioplasty of the infarct-related artery for acute myocardial infarction. After excluding those with interim interventions (64), medical events (36), or medical contraindications to follow-up testing (25), both a treadmill test and a cardiac catheterization were completed in 144 patients, 88% of those eligible for this assessment. Four patients with left bundle branch block or pacemaker rhythm at the time of treadmill testing were also excluded from analysis. Of six follow-up clinical and treadmill variables examined by multivariable logistic regression analysis, only exercise ST deviation was independently correlated with restenosis at follow-up (chi 2 = 5, p = 0.02). The clinical diagnosis of angina at follow-up, although marginally related to restenosis when considered by itself (p = 0.04), did not add significant information once ST deviation was known. The sensitivity of ST deviation of 0.10 mV or greater for detecting restenosis was only 24% (13 of 55 patients), and the specificity was 88% (75 of 85 patients). The sensitivity of exercise-induced ST deviation for detection of restenosis was not affected by extent or severity of wall motion abnormalities at follow-up, by the timing of thrombolytic therapy or of angioplasty, or by the presence of collateral blood flow at the time of acute angiography. A second multivariable analysis evaluating the association of the same variables with number of vessels with significant coronary disease at the 6-month catheterization found an association with both exercise ST deviation (p = 0.003) and exercise duration (p = 0.04). Angina symptoms and exercise treadmill test results in this population had limited value for predicting anatomic restenosis 6 months after emergency angioplasty for acute myocardial infarction.     

Prognostic value of exercise-induced ventricular ectopic activity for mortality after acute myocardial infarction

To evaluate the importance of ventricular ectopic activity on the predischarge treadmill exercise test for predicting mortality in patients after acute myocardial infarction (AMI), 163 patients with uncomplicated AMI were studied using symptom limited low-level treadmill exercise testing and 24-hour ambulatory electrocardiographic monitoring before hospital discharge. All patients were followed for at least 2 years or until recurrent AMI, coronary artery bypass grafting or death. Seventeen patients (10%) died during the follow-up period, 15 patients (9%) had recurrent AMI and 45 patients (28%) underwent bypass surgery. Ventricular ectopic activity was the only single treadmill abnormality that predicted subsequent cardiac death; angina pectoris, electrocardiographic ST-segment depression and a hypotensive blood pressure response did not. The mortality rate in the 20 patients with exercise-induced ventricular ectopic activity was 25%, compared with 8% in those without (p less than 0.004). Furthermore, in this patient population, exercise-induced ventricular ectopic activity was a much better predictor of cardiac death than that detected by ambulatory monitoring. Thus, ventricular ectopic activity on the predischarge treadmill exercise test is an important risk factor for death after AMI.