Comparison of heart rate reserve, age predicted maximum heart rate and rate pressure product as predictors of future cardiovascular events following a negative dobutamine stress echocardiogram

Background: Dobutamine stress echocardiography (DSE) is a commonly used diagnostic stress test for the assessment of various cardiac pathologies on patients unable to perform exercise. Unlike exercise, there is no reliable subjective termination end-point such as fatigue to rely on. Consequently, DSE’s are often concluded at a predetermined age predicted maximal heart rate (APMHR) such as 85%. The aim of this study was to assess if APMHR, heart rate reserve (HRR) and the maximum rate pressure product (MRPP) are valid measures of future cardiovascular (CV) events in otherwise negative DSEs.Methods: Following exclusions, receiver operating curve (ROC) analyses were performed on 652 patients using CV events during the follow-up period (4.2 ± 1.8 years) as the outcome variable.Results: ROC analyses failed to produce a statistically valid model for MRPP (p = .227, area under curve (AUC)=0.55) with a sensitivity and specificity of 21.1% and 91.9%, respectively at the optimal cut point (14948 MRPP). To the contrary, APMHR produced a sensitivity and specificity of 74.7% and 60.9%, respectively (p < .0001, AUC = 0.715). HRR however, with a sensitivity and specificity of 67.4% and 68.2% (p < .0001, AUC = 0.718) was the only predictor of CV events following Cox analysis (p < .0001).Conclusions: This study demonstrates MRPP as a poor measure of CV event prediction during DSE. While an APMHR of 89.3% demonstrated a statistically valid model, HRR was the only predictor of CV events in otherwise negative DSEs.