Abstract 322: SPECT Myocardial Perfusion Imaging and the Risk of Sudden Cardiac Death in Patients With Coronary Disease and Left Ventricular Ejection Fraction >35%
Background: Most victims of sudden cardiac death (SCD) have a left ventricular ejection fraction (LVEF) >35%. The goal of this study was to determine if SPECT myocardial perfusion imaging (MPI) is an effective method of risk stratification for SCD in patients with coronary artery disease (CAD) and LVEF >35%.
Methods and Results: The study population included 4865 patients with CAD and LVEF >35% who underwent gated SPECT MPI. Cox proportional hazard modeling was used to examine the relationship between patient characteristics and SCD. The median age was 63 years (IQR 54–71) and the median LVEF was 56% (IQR 50–64). During the follow-up period (median of 3.0 years (IQR 1.3–6.2), there were 161 SCDs (3.3%). Higher summed stress scores (SSS) were associated with an increased incidence of SCD (Figure⇓; p<0.0001). After multivariable adjustment, LVEF, the Charlson index, hypertension, smoking, anti-arrhythmic drug therapy, and the SSS were associated with SCD (all p<0.05). For each 3 unit increase in the SSS, the HR for SCD was 1.13 [95% CI 1.04–1.23]). The addition of perfusion data to the clinical history and LVEF was associated with increased discrimination for SCD events (c-index 0.728). Using the Cox model, we constructed a nomogram for projected SCD rates that maintained discriminatory ability and was validated by bootstrap analysis (c-index 0.72 [95% CI 0.68–0.76]).
Conclusions: Among patients with CAD and LVEF >35%, the extent of stress MPI perfusion defects is associated with an increased risk of SCD. Future large, prospective studies should address the role of perfusion imaging in the identification of high-risk patients with LVEF >35% who may benefit from ICD implantation.