Long-term preservation of left ventricular function in medically treated patients with coronary artery disease and persistent exercise-induced ischemia.

Little information is available on the long-term evolution of left ventricular function of medically treated patients with coronary artery disease and gross limitation of coronary flow reserve. The aim of this study was to assess the long-term evolution of effort tolerance and left ventricular function and their relation to the control of ischemic events in patients with coronary artery disease and prolonged inducible exercise-induced myocardial dysfunction who either declined or were ineligible for cardiac revascularization.

Specificity and sensitivity of exercise-induced ST segment elevation for detection of residual viability: comparison with fluorodeoxyglucose and positron emission tomography.

OBJECTIVES: We evaluated the sensitivity and specificity of exercise-induced ST segment elevation for the detection of residual myocardial viability. BACKGROUND: Assessment of residual viability after myocardial infarction is relevant for establishing indication for revascularization. We have previously shown that exercise-induced ST segment elevation is a marker of residual viability. METHODS: We studied 34 patients with a previous Q wave myocardial infarction (anterior in 21, inferior in 13) of whom 18 (group A) had exercise-induced ST segment elevation in more than one lead (mean [+/- SD] 1.8 +/- 0.9 mm, range 1 to 4) and 16 (group B) did not. All patients underwent rest technetium-99m methoxyisobutyl isonitrile single-photon emission computed tomography (SPECT), fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography and coronary angiography. The time elapsed between the infarction and the viability study was 72 +/- 108 days (range 15 to 400) in group A and 516 +/- 545 days (range 14 to 1,800) in group B. RESULTS: The presence and site of previous infarction were confirmed by SPECT studies in all 34 patients. Uptake of F-18 fluorodeoxyglucose within the infarcted area was present in 18 of 18 patients in group A but in only 9 (56%) of 16 in group B (p < 0.01). In patients with an anterior infarction, the sensitivity, specificity and predictive accuracy of exercise-induced ST segment elevation for detection of residual viability were 82%, 100% and 86%, respectively (95% confidence intervals 46% to 83.5%, 59% to 100% and 55.6% to 87.1%, respectively). CONCLUSIONS: Exercise-induced ST segment elevation in infarct-related leads has a high specificity and acceptable sensitivity for detection of residual viability within the infarcted area.

Antiischemic effects of intravenous diazepam in patients with coronary artery disease.

Diazepam (DZP) is commonly used in treatment of patients with acute ischemic syndromes to allay anxiety, but benzodiazepines reduce myocardial contractility and increase myocardial blood flow. To investigate the antiischemic effect of DZP, we studied 13 patients with a positive exercise test and angiographically documented coronary artery disease. All patients were submitted to a randomized, placebo-controlled trial using 0.9% NaCl infusion as placebo and intravenous (i.v.) diazepam (0.1 mg/kg in 20 min). Exercise tests performed immediately after the infusions showed that as compared with placebo, DZP significantly prolonged time to 1-mm ST-segment depression (557 +/- 198 vs. 428 +/- 226 s, p < 0.0001) and total exercise duration (624 +/- 177 vs. 561 +/- 188 s, p < 0.007). Rate-pressure product (RPP) at 1-mm ST-segment depression was not significantly different with the two treatments. DZP significantly delays onset of exercise-induced myocardial ischemia in patients with coronary artery disease. Because RPP at onset of ischemia was similar to that recorded with placebo despite greater levels of external workload, the antiischemic action of DZP appears to be mediated, at least partially, by a reduction in myocardial oxygen consumption.

Prevalence of silent myocardial ischaemia during exercise stress testing. Its relation to effort tolerance and myocardial perfusion abnormalities.

The number of underperfused myocardial segments, the extent of coronary artery disease and the severity of impairment of coronary flow reserve were compared in 147 consecutive patients exhibiting painful or painless ischaemic ST segment depression on exercise testing. Of 147 patients, only 61 (41%) experienced angina (group 1) whilst 86 (59%) did not (group 2). In the two groups coronary disease was comparable for both extent and distribution, and neither the location of transient perfusion defects nor their relation to areas of old myocardial necrosis appeared to influence the presence or absence of chest pain. However, exercise duration, exercise time and rate-pressure product at the beginning of ischaemia were lower in group 1. Furthermore, a greater proportion of asymptomatic patients had only one ischaemic segment on 99mTc-MIBI perfusion scintigraphy. We conclude that: (1) in patients with effort angina and coronary disease, the incidence of electrocardiographic silent ischaemic events induced by exercise is similar to that observed in studies based on continuous ECG monitoring. (2) Exertional angina is more frequently associated with greater ischaemic areas and with more severe degrees of impairment of residual coronary flow reserve. (3) The presence of an old myocardial infarction does not appear to influence the incidence of ischaemic cardiac pain.