Prognostic value of coronary flow and heart rate reserve in emergency department chest pain

Abstract

Abstract Aims To estimate the prognostic value of stress echo (SE) with the assessment of coronary flow velocity reserve (CFVR) and heart rate reserve (HRR) in patients admitted for chest pain with non-diagnostic EKG, negative troponin, and without inducible regional wall motion abnormalities (RWMA). Methods 658 patients (age 67±12 years) admitted to our Emergency Department with chest pain, non-diagnostic EKG, and negative serial troponin underwent dipyridamole (0.84 mg/kg in 6') SE with simultaneous assessment of RWMA, CFVR in the left anterior descending artery, and HRR as peak/rest heart rate. The outcome measure was all-cause mortality. Results Of the 658 patients initially enrolled, 20 (3%) showed RWMA during SE and were referred to ischemia-driven revascularization. In the remaining 638, CFVR was abnormal (<2.0) in 148 patients (23%). HRR was abnormal (<1.22 in patients in sinus rhythm, or <1.17 in patients with permanent atrial fibrillation) in 196 patients (31%). The main clinical and echocardiographic characteristics according to CFVR and HRR response are shown in Table 1. During a follow-up of 7.3±4.3 years, 151 (24%) patients died. Survival at 8 years was 93% in patients with normal CFVR and HRR, 76% in patients with abnormal CFVR only, 73% in patients with abnormal HRR only, and 38% in those with abnormal CFVR and HRR (p<0.0001) (Figure 1). At multivariable analysis, abnormal CFVR (HR 1.49, 95% CI 1.05–2.10, p=0.02) and abnormal HRR (HR 2.01, 95% CI 1.43–2.84, p<0.0001) were independent predictors of survival. Conclusions In admitted patients with non-ischemic EKG, negative serial troponin, and whitout RWMA during dipyridamole SE, a reduced CFVR and blunted HRR independently identify a subset with worse survival in the long-term. Funding Acknowledgement Type of funding sources: None.