Abstract
Background
A blunted heart rate (HR) response during dipyridamole myocardial perfusion imaging have been associated with a poor outcome.
Aim
To assess the value of HR response in patients undergoing high dose dipyridamole stress echocardiography (SE).
Methods
We retrospectively selected a consecutive sample of 1,622 patients (none with pacemakers or atrial fibrillation), mean age 66±12 years, 431 (27%) on beta-blockers. All underwent high dose (0.84 mg/kg) dipyridamole SE for known or suspected coronary artery disease and/or heart failure from January 1988 to January 2018 in our Cardiology Division. HR (with 12-lead ECG) was obtained each minute and recorded at rest and peak stress. HR reserve (HRR) was calculated as the peak/rest HR ratio. All patients were followed-up. The composite end-point was made of all cause-death, non-fatal myocardial infarction and late (>3 months) symptoms-driven myocardial revascularizations.
Results
SE was positive for regional wall motion abnormalities (RWMA) in 192 patients (12%). HR increased (rest=70±11 beats/min vs stress= 92±17 beats/min, p<0.0001). During a median follow-up time of 904 days, 462 events occurred: 73 deaths, 57 non-fatal myocardial infarctions, 332 myocardial revascularizations. Receiver operating curve analysis identified a HRR ≤1.27 as the best cutoff. At multivariate analysis a reduced HRR was a significant predictor of hard events (Hazard Ratio, HR=2.02, 95% Confidence Intervals, CI, 1.38–2.95, P<0.0001), additive to ischemic regional wall motion abnormalities (HR=2.11, 95% CI 1.28–3.48, P=0.004), resting RWMA (HR =1.88, 95% CI 1.31–2.72, P<0.001), age (HR =1.06, 95% CI 1.04–1.08, P<0.001) and beta-blockers at the time of testing (HR =1.55, 95% CI 1.06–2.29, P=0.03). Five-year hard event-free survival increased from 6% to 26% from the highest to the lowest HRR quartile: see figure.
Survival curve
Conclusion
A blunted HRR is a useful non-imaging predictor of adverse events during high dose dipyridamole-SE. It is additive over resting or inducible regional wall motion abnormalities, and unmasks a prognostically meaningful autonomic unbalance. Chronotropic incompetence during dipyridamole SE is a negative prognostic finding, equally important than RWMA.
166 Importance of left ventricular remodelling and regional wall motion abnormalities in the occurrence of functional ischemic mitral regurgitation
