Age-related Changes in Clinical and Prognostic Significance of Exercise-induced Angina

Abstract

Exercise-induced angina (EA) is an important menifestation of myocardial ischemia in stress testing. However, whether or not the presence of EA indicates a greater severity and worse prognosis of coronary artery disease is uncertain. It is well known that the elderly have a greater prevalence of silent myocardial infarction. This suggests that the incidence and significance of EA in elderly patients may differ from those in the younger patients. Therefore, we, at first, studied the age-related change in the incidence of EA by reviewing 983 consecutive treadmill tests. Furthermore, to evaluate the age-related change of the clinical and prognostic significance of EA, exercise tests, angiographic findings and 29 months follow-up data were assessed in 142 patients without prior myocardial infarction who underwent treadmill test and coronary angiography (CAG) for the investigation of coronary artery disease. The rate of positive test results among 983 treadmill tests exceeded 30% only in patients 60 years old or older. Accordingly, we divided the patients into two different age groups: middle-aged patients (≤59yr, M-patients) and elderly patients (≥60yr, O-patients). Among 983 treadmill tests, O-patients had a higher rate of positive results (presence of EA or positive ECG criteria) than M-patients (36 vs. 24%, p<0.001). However, incidence of EA was similar in the 2 groups (17 vs. 14%). Among 142 CAG patients, there were no differences in rate of positive test results (72 vs. 69%), incidence of EA (53 vs. 59%), average number of diseased vessels (1.5±1.1 vs. 1.3±1.1) between the O-patients and M-patients. In M-patients with EA exercised shorter than patients without EA (6.3±2.1 vs. 8.6±3.0min., p<0.001) with a greater ST index (-1.8±1.5 vs. -0.3±2.2, p<0.001) and ST/HR slope (15.3±11.7 vs. 8.1±8.8μV/bpm, p<0.05) and had higher severity of diseased vessels (1.7±1.0 vs. 0.9±1.0 p<0.01). Moreover, higher incidences of subsequent revascularization (67 vs. 21%, p<0.001) and remaining anginal symptoms (33 vs. 14%, p<00.05) were also observed in patients with EA than patients without EA. By contrast, in O-patients, none of these differences were observed between patients with and without EA. Cardiac death occurred in 3 patients with EA (1 in M-patients, 2 in O-patients). Subsequent myocardial infarction occurred in 4 patients with EA (1 in M-patients, 3 in O-patients) and in 1 without EA in O-patients. Thus, clinical and prognostic significance of anginal pain during exercise testing varies in accordance with aging. Even when angina is not induced by treadmill test in patients without myocardial infarction, elderly patients could not be expected to show clinical and prognostic significance as good as that observed in middle-aged patients without exercise-induced angina.