Mortality among patients undergoing dipyridamole 99mTc Sestamibi SPECT: impact of blunted heart rate response and abnormal scans

Abstract

Abstract Background Blunted heart rate response (BHRR) caused by cardiac neuropathy associated with dipyridamole stress, has been linked to cardiovascular (CV) outcome events. Whether BHRR is necessarily associated with abnormal perfusion is unknown. The aim of the study was to assess the incremental prognostic value of BHRR in a single center population undergoing Dipyridamole 99mTc Sestamibi SPECT test (DSPECT) for predicting late CV events. Methods 388 patients (aged 73±10 years, 45% females, 51% with known coronary disease) that underwent DSPECT over 3 years period were included. Abnormal DSPECT and BHRR were evaluated in relation to late death. Results Mean follow up period was 1560±565 (15–2431) days. During follow up period, 90 patients died. Mode of death was CV in 20 and non-CV in 70. BHRR (<20% heart rate increase), abnormal DSPECT, post-stress LVEF <60% and reversible defects were observed in 63%, 41%, 23% and 20% of patients, respectively. BHRR (HR -2.41, p<0.0006) and abnormal DSPECT (HR-1.62, p=0.02) were predictors of all-cause death. BHRR had incremental prognostic value over abnormal DSPECT (Figure, p<0.0005). Multivariable analysis identified age, dyspnea, insulin treated diabetes mellitus and dialysis as independent predictors of death while DSPECT and BHRR did not. However, BHRR remained a significant predictor of CV death [HR 8.1 (1.06, 62.0), p<0.05]. Conclusions In this contemporary DSPECT cohort, BHRR and DSPECT failed to predict all-cause mortality. However, BHRR was an independent predictor of CV death. Funding Acknowledgement Type of funding sources: None. BHRR stratifies abnormal DSPECT