Prognostic value of regadenoson stress myocardial perfusion imaging in patients with left bundle branch block or ventricular paced rhythm

Background Vasodilator stress myocardial perfusion imaging (MPI) is the provocative test of choice in patients with left bundle branch block (LBBB) or ventricular paced (V-paced) rhythm. The prognostic value of regadenoson SPECT myocardial perfusion imaging (MPI) in these patients has not been studied. Methods and Results We conducted a retrospective cohort study of 562 patients [mean age, 69 +/- 11 years; men, 53.3%] with LBBB (50.7%) or V-paced rhythm (49.3%) who underwent regadenoson stress SPECT-MPI. There were 321 (57.1%) subjects with abnormal MPI and 192 (34.2%) with myocardial ischemia. During a mean follow-up of 2.5 +/- 1.9 years, 39 (6.9%) patients had a major adverse cardiac event (MACE), defined as cardiac death or myocardial infarction. The annualized MACE rate in patients with normal MPI was 0.9% (LBBB, 0.8%; V-paced, 1.0%). There was a significant stepwise increase in MACE rates with increasing burdens of perfusion abnormality (P < 0.001) and myocardial ischemia (P = 0.001). Increased risk with abnormal MPI [adjusted hazard ratio, 4.26; P = 0.001] and myocardial ischemia [adjusted hazard ratio, 2.70; P = 0.003] was independent of and incremental to important clinical covariates. Abnormal MPI and myocardial ischemia predicted MACE similarly in both LBBB and V-paced subgroups (interaction P values > 0.05). Conclusion In patients with LBBB and V-paced rhythm, regadenoson stress SPECT-MPI provides independent and incremental prognostic value in predicting adverse cardiac events.