Prognostic implications of transient asymptomatic myocardial ischemia as detected by ambulatory electrocardiographic monitoring

[Significance of silent myocardial ischemia for identification and optimal therapy of patients with latent coronary heart disease. Is there a marker for prognostic indication for PTCA?]

Although percutaneous transluminal coronary angioplasty (PTCA) improves the symptomatic status and exercise capacity of patients with coronary artery disease and stale or unstable angina pectoris, a beneficial effect on long-term prognosis has not been convincingly demonstrated so far. In totally asymptomatic patients with coronary artery disease, however, decision to undertake PTCA is greatly influenced by prognostic considerations. Usually, detection of silent myocardial ischemia in non-invasive examinations (exercise stress testing, ambulatory electrocardiographic monitoring) precedes the angiographic diagnosis of coronary artery disease in these patients.

Persistent transient myocardial ischemia despite beta-adrenergic blockade predicts a higher risk of adverse cardiac events in patients with coronary artery disease

OBJECTIVES

We evaluated the prevalence and prognostic significance of transient myocardial ischemia despite beta-adrenergic blockade in patients with coronary artery disease.

BACKGROUND

Persistence of transient ischemia despite therapy may correspond to a subset of high risk patients with coronary disease. The impact of beta-blocker withdrawal in these patients remains unknown.

METHODS

Patients (n = 313) with documented coronary artery disease and beta-blocker therapy, with (group I, n = 84) or without (group II, n = 229) transient ischemia on ambulatory electrocardiographic monitoring, were followed up during 21 +/- 9 months for cardiac events (death, myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass surgery and worsening angina). Occurrence of events was compared by log-rank test.

RESULTS

The number of coronary stenoses did not differ significantly between groups I and II. Beta-blocker therapy was discontinued more frequently during follow-up in group II (25% vs. 14% in group I, p = 0.04). Cumulative percentage of death or myocardial infarction, or both, tended to be higher in group I a 30 months (17% vs. 5% in group II, p = 0.09). Coronary angioplasty and bypass surgery were significantly more frequent in group I (p = 0.01 and 0.0008, respectively). Transient ischemia was associated with a higher cumulative probability of adverse events (p = 0.004). The number of coronary stenoses, presence of transient ischemia and beta-blocker withdrawal were the only significant prognostic factors of cardiac events in the Cox model. In group I patients, the relative hazard of cardiac events was increased threefold when beta-blocker therapy was interrupted.

CONCLUSIONS

These data suggest that 1) the occurrence of transient ischemia despite beta-blocker therapy identifies a subset of high risk patients with coronary artery disease, and 2) the interruption of beta-blocker therapy increases the risk of adverse cardiac events.

Prevalence, characteristics, and risk stratification of electrocardiographic and symptomatic silence of myocardial ischemia despite scintigraphically evidenced ischemia in symptomatic patients presenting with severe coronary artery stenosis

Symptoms of angina pectoris and transient ST-segment depression are most commonly used to evidence acute myocardial ischemia during exercise testing. However, the diagnostic accuracy of either or both criteria in relation to clinical characteristics and the patient's exercise response has been a subject of controversy. The prevalence and severity of symptoms of angina pectoris and/or ST-segment depression were studied prospectively in 147 consecutive patients with a history of daily angina pectoris, scintigraphic evidence of exercise-induced myocardial ischemia, and coronary artery stenosis > 75%. Logistic regression analysis was applied to determine absence of any or both criteria by the clinical characteristics or exercise response of the patient. During exercise testing, ST-segment response failed to prove scintigraphically evidenced myocardial ischemia in 14/147 patients (10%) and 35/147 patients (24%) when ST-segment depression > or = 0.1 in either > or = 1 or > or = 2 ECG leads was chosen. Symptoms of angina pectoris were found to be absent in 69/147 patients (47%). Only 58 patients (40%) suffered from angina and met the ECG criterion at the time of scintigraphic myocardial ischemia. Absence of ST-segment depression was best predicted by clinical variables such as large myocardial infarction (increase: 2.6 times, p = 0.007), number of stenoses < or = 2 (2.0 times, p = 0.023), and presence of diabetes mellitus (4.3 times, p = 0.035). Painless myocardial ischemia was determined by blood response to exercising. Thus, a double product > 23 increased the risk of painless myocardial ischemia by 1.5 times (p = 0.017).(ABSTRACT TRUNCATED AT 250 WORDS)