Prognostic significance of double product and inadequate double product response to maximal symptom-limited exercise stress testing after myocardial infarction in 6296 patients treated with thrombolytic agents

Background The aim of this study was to evaluate the prognostic significanc e of the pressure-rate product (PRP) obtained during exercise stress testin g and of its change from rest to maximal exercise (dPRP) in a population of survivors of acute myocardial infarction treated with thrombolytic agents. Methods and Results survivors of acute myocardial infarction (n = 6251) fro m the GISSI-2 database, who underwent a maximal symptom-limited exercise te st with either bicycle ergometer or treadmill, were followed up for 6 month s. PRP and dPRP values were dichotomized ( less than or equal to 21,700 and > 21,700, less than or equal to 11,600 and > 11,600, respectively) and ana lyzed in a multivariate Cox model individually and simultaneously with othe r ergometric variables. Six-month mortality rate was 0.8% in the high PRP g roup and 2.0% in the low PRP group. Low PRP was an independent predictor of 6-month mortality rate (relative risk [RR] 1.97, 95% confidence interval [ CI] 1.24 to 3.13). Patients with low dPRP had mortality rates higher than p atients with high dPRP (2.1% vs 0.8%). At the multivariate analysis, low dP RP showed negative predictive value (RR 1.97 95% Cl 1.23 to 3.16). A furthe r multivariate analysis was per formed with PRP and dPRP, also adjusting Fo r low work capacity, abnormal systolic blood pressure response to exercise, and symptomatic-induced ischemia. The results showed that low work capacit y, low PRP, and symptomatic exercise-induced ischemia were still significan tly associated with higher 6-month mortality rate (P = .04,.02, and .05; RR = 1.68, 1.71, and 1.78 respectively). Conclusions PRP is a predictive index to assess prognosis in survivors of a cute myocardial infarction treated with thrombolytic agents able to perform an exercise test after acute myocardial infarction, but its usefulness app ears to be limited, considering that these patients were at low risk.