Usefulness of exercise echocardiography in predicting cardiac events in an outpatient population

Abstract

The prognostic value of exercise echocardiography in an outpatient population is not well defined. A total of 1,020 consecutive patients referred for exercise echocardiography in an ambulatory care setting were studied by reviewing their medical records and exercise echocardiographic data. Of these, 71 (7%) were excluded due to technically inadequate tests, leaving 949 patients who were included in the analysis. A positive exercise echocardiogram (EE) was defined as an appearance of a new wall motion abnormality or worsening of a baseline abnormality. Cardiac events, defined as myocardial infarction, coronary angioplasty, coronary bypass surgery, and death, were documented during a 12-month follow-up period. Cardiac events occurred in 17% of patients (26 of 152) with a positive exercise echocardiogram (EE) and in 2.5% (20 of 797) with a negative EE (p <0.001). The incidence of myocardial infarction (2.6% vs 0.4%, p <0.02), coronary angioplasty (7% vs 1%, p <0.001), and coronary bypass surgery (9% vs 1%, p <0.001) were higher in patients with a positive versus a negative EE. There was 1 death in the positive study group and none in the negative group. Significant independent variables (p <0.05) that predicted cardiac events included a positive exercise electrocardiogram, history of coronary angioplasty, nonspecific ST-T changes on the baseline electrocardiogram, double product <25,000, men, chest pain on exercise test, and a positive exercise electrocardiogram. On a stepwise logistic regression model, exercise echocardiography emerged as an independent predictor of future cardiac events in an outpatient population. This predictive value was enhanced in the presence of a positive exercise electrocardiogram compared with a negative exercise electrocardiogram (24.2% vs 7.9%, p <0.03). Our study suggests that exercise echocardiograhy is an independent predictor of future cardiac events in an outpatient population.