Can Dobutamine Stress Echocardiography Predict Cardiac Events in Nonrevascularized Diabetic Patients Following Acute Myocardial Infarction: Patient Follow-up
“Hard” outcome events were cardiac death and nonfatal reinfarction, while “all events” included hard events and unstable angina. Cardiac death was defined as death with documentation of significant arrhythmia or cardiac arrest, or both, or death attributable to congestive heart failure or myocardial infarction in the absence of any other precipitating factors. For patients who died outside of the hospital and did not receive an autopsy, sudden unexpected death was attributed to a cardiac cause. The recurrence of AMI was defined using the standard criteria of history, ECG, and cardiac enzyme levels. Unstable angina was defined as accelerating anginal symptoms requiring hospital readmission, or progression of symptoms requiring revascularization. Because the decision for bypass surgery and coronary angioplasty might be subjective, the outcomes of patients with revascularization were excluded from the final data analysis. Only the most severe outcome was considered an end point during the follow-up period after patients with planned revascularization were excluded. fully
Results are expressed as mean ± SD for continuous variables and as percentages for categorical variables. Baseline variables and the positive and negative predictive values of DSE for future events were compared between groups using the x2 or t test. The predictive values of several clinical and DSE variables for event-free survival were evaluated by a stepwise Cox regression analysis. Relative risk and 95% confidence intervals were also calculated. The relative risk of dobutamine time was determined after every additional infusion minute. The event-free survival (Kaplan-Meier) of patients with a negative DSE result was determined, and the differences between survival curves were tested with the log rank test. The Cox proportional regression model was used to identify significant independent predictors of new cardiac events, including age, gender, hypertension, smoking, peripheral arterial disease, left ventricular ejection fraction, tissue plasminogen activator treatment, infarct area, Killip classification, NYHA functional class (I vs II and III), WMSI at rest and peak stress, dobutamine time, and positive DSE result. All statistical analyses were performed using appropriate software (SPSS for Windows, Release 6.0; SPSS; Chicago, IL). A p value < 0.05 was considered statistically significant.