Abstract 2651: Ischemic Cascade: Sequence of ECG, Acoustic Cardiographic Changes, and Angina during Coronary Occlusion

Abstract

Background: Previous studies suggest that ventricular function may be impaired without or prior to ECG changes during ischemia. Using diastolic third and fourth heart sounds (S3 and S4), a non-invasive measurement of ventricular function, our study investigated whether diastolic heart sounds occur earlier than electrical changes or angina during ischemia. Methods: To determine the sequence of ECG, diastolic heart sounds, and anginal ischemic symptoms, a prospective observational study was performed in 21 subjects undergoing cardiac catheterization and percutaneous coronary intervention (PCI). Subjects had both ST-segment amplitude changes >2 standard deviations above the baseline during PCI-related coronary occlusion, as well as new or increased intensity S3 or S4 measured by computerized acoustic cardiography. The sequence of resolution of these noninvasive signs of ischemia was also examined following balloon deflation. Results: Electrocardiographic ST amplitude changes were the earliest sign of ischemia (mean onset, 21 seconds), and they were also the first to resolve after balloon deflation. New or increased intensity diastolic heart sounds followed ECG changes (mean onset S4, 24.7 seconds; S3, 38.1 seconds: Tables 1 & 2 ). Anginal symptoms occurred in only 2 of the 21 subjects during ischemia with a mean onset time of 67.5 seconds. Conclusion: ECG signs of ischemia precede functional changes as measured by new or intensified S3 and/or S4. Angina rarely occurs during PCI-induced ischemia, but if present, is the last event in the ischemic cascade. Table 1. Sequence of noninvasive signs of ischemia during coronary occlusion (n=21) Table 2. Resolution of noninvasive signs of ischemia after balloon deflation (n=18)