L Dyke

Effect on prognosis of abolition of exercise-induced painless myocardial ischemia by medical therapy☆

During exercise radionuclide ventriculography, many patients with coronary artery disease exhibit painless myocardial ischemia defined as an abnormal left ventricular ejection fraction response without accompanying angina. To see if complete suppression of such exercise-induced painless ischemia by anti-ischemic medication implies a better prognosis in medically treated coronary artery disease, 34 patients underwent repeat testing at 4 weeks receiving regular conventional therapy that rendered angina no worse than class I. With such therapy, painless ischemia was abolished in 12 patients (group I) and persisted in 22 (65%, group II). Both groups were similar in age, number of diseased vessels, proportion with previous myocardial infarction, exercise ejection fraction, and degree of exercise-induced painless ischemia at baseline. At 9 months, adverse events had occurred in 11 patients (2 patients with myocardial infarction, 4 with unstable angina, 2 with angioplasty and 3 with bypass surgery). Only 1 of 12 patients (8%) in group I had experienced events compared with 10 of 22 (45%) in group II (chi-square, 5.4; p less than 0.025; 95% confidence interval, 12 to 61%). Thus, the relative risk of adverse events in patients whose painless ischemia was abolished was only 18% of that in patients in whom it was persistent. These results suggest that (1) the abolition of exercise-induced painless ischemia by conventional symptom-dictated medical therapy confers a better short-term prognosis in medically treated coronary artery disease, and (2) therapeutic efficacy may need to be assessed by titration against ischemia and not against angina.

Exercise testing without interruption of medication for refining the selection of mildly symptomatic patients for prognostic coronary angiography.

OBJECTIVE--To examine how exercise testing on background medical treatment affects the ability of the test to predict prognostically important patterns of coronary anatomy in patients with a high clinical probability of coronary artery disease but who are well controlled on medication. DESIGN--Prospective study. SETTING--Regional cardiothoracic centre and referring district general hospital. PATIENTS--84 patients with a history of typical angina or definite myocardial infarction and mild symptoms who had been placed on the waiting list for prognostic angiography. INTERVENTION--Maximal exercise electrocardiography and radionuclide ventriculography performed off and on medication, followed by angiography within three months. MAIN OUTCOME MEASURE--Prognostically important coronary artery disease for which early surgery might be recommended purely on prognostic grounds, irrespective of symptoms. RESULTS--Coronary artery disease was present in 71/84 (85%) patients; in 28/84 (33%) patients this was prognostically important. When the result was strongly positive, the predictive accuracy for prognostically important disease was 0.46 off and 0.62 on medication for the exercise electrocardiogram and 0.71 off and 0.82 on medication for exercise radionuclide ventriculography. The likelihood ratio was 1.00 off and 1.36 on medication for exercise electrocardiography and 2.54 off and 10.5 on medication for exercise radionuclide ventriculography. In stepwise logistic regression, the test identified as the strongest predictor of prognostically important disease was exercise radionuclide ventriculography on medication for which the improvement chi 2 was 28 (p < 0.0001). With the regression model, the probability of important disease is 92% if exercise radionuclide ventriculography on medication is at least strongly positive, compared with 16% if the result is normal or just positive. CONCLUSION--In patients likely to have coronary disease, exercise testing should be performed without interruption of medication to optimise its ability to identify those with prognostically important disease, and to help to avoid unnecessary or premature angiography in those who are well controlled on medical treatment.

SUPPRESSION OF INDUCIBLE PAINLESS MYOCARDIAL-ISCHEMIA BY CONVENTIONAL MEDICAL THERAPY - EFFECT ON SHORT-TERM OUTCOME AND LEFT-VENTRICULAR SYSTOLIC FUNCTION

To test the hypothesis that abolition of exercise-induced painless myocardial ischemia by anti-ischemic medication improves prognosis in patients with medically treated coronary artery disease, we studied such patients with painless ischemia during exercise radionuclide ventriculography performed after temporary discontinuation of medication. The test was repeated while patients received conventional medical therapy that rendered angina no worse than New York Heart Association class I. The relative risk of adverse cardiac events was reduced by > 5-fold when painless ischemia was abolished by symptom-dictated therapy. Thus, the abolition of exercise-induced painless ischemia by conventional medical therapy carries a better short-term prognosis in medically treated coronary artery disease, suggesting that therapeutic efficacy may need to be assessed by titration against ischemia and not angina. In patients without overt cardiac events, there were no significant differences between baseline and 12-month measurements of ejection fraction at rest, peak exercise, and the change in ejection fraction from rest to exercise. Thus, in those who remain asymptomatic and event-free, painless ischemia that is easily inducible at baseline despite medication does not lead per se to deterioration of left ventricular systolic function at rest or during exercise over 12 months. Such an effect, if evident as early as at 12 months, would favor a strategy of early revascularization over medical treatment in asymptomatic patients who have inducible painless ischemia despite medication.

Long-term effect of inducible silent ischaemia on left ventricular systolic function

Silent myocardial ischaemia is readily detected by exercise radionuclide ventriculography in patients with coronary artery disease. In those who remain asymptomatic and event-free, it is not known whether silent ischaemia which is inducibledespite anti-ischaemic medication exerts an insidious detrimental effect on left ventricular function. To study this, 34 medically treated patients (mean age 57; 26 men) underwent prospective measurement of left ventricular ejection fraction (LVEF) during rest and exercise radionuclide ventriculography without interruption of anti-ischaemic medication at baseline and 12 months later.There was no significant mean (standard deviation, 95% confidence interval) deterioration from baseline to 12 months in LVEF at rest (50% v 49%, SD 5; 95% CI=−3 to+1), peak exercise (44% v 45%, SD 8; 95% CI=−1 to + 4) and the change in LVEF from rest to exercise (−6% v – 4%, SD 7; 95% CI=−1 to + 5).Thus, in coronary artery disease patients who remain asymptomatic and event-free on medical therapy, silent myocardial ischaemia which is readily inducible at baseline despite medication does not leadper se to deterioration of left ventricular systolic function at rest or exercise over 12 months.