LEFT VENTRICULAR MASS, PUMP PERFORMANCE AND CARDIOVASCULAR EVENTS: THE STRONG HEART STUDY: PP.22.374

Abstract

Background: Ejection-phase indices of LV function such as ejection fraction (EF) are strong prognostic indicators. However, at given level of EF, LV pump performance (stroke volume [SV]) may differ, depending on LV size. but, it is unknown whether low SV is a prognostic marker independent of its strong biological collinearity with high LV mass (LVM). We assessed the associations of EF, SV and LVM with cardiovascular (CV) events in a large population free of CV disease. Method: After the 2nd SHS exam, we examined 8-year outcome of quintiles of EF, SV (z-derived method) and LVM in 2323 participants (58 ± 7 yrs; 62% women) without prevalent coronary heart disease, stroke or heart failure (hypertension in 39%, diabetes in 45% and obesity in 54%). Results: In univariate Cox models, risk of composite fatal or non-fatal cardiovascular (CV) events increased across lower quintiles of EF (log rank = 21.7; p = 0.0002) and higher quintiles of LVM (log rank = 40.8; p < 0.00001). In contrast SV did not show significant predictive value. LVM was negatively related to EF (r = −0.37), but was positively correlated with SV (r = 0.66), (both p < 0.0001). Thus, the level of LVM, could confound evaluation of the association of SV with subsequent CV events. Thus, we evaluated LV pump performance per gram of LVM (SV/LVM). Kaplan Meier curves revealed a progressively higher rate of CV events with lower quintiles of SV/LVM (log Rank = 36.3; p < 0.0001). Cox regression, adjusting for age and sex and including EF, SV and LVM showed that hazard of incident CV events increased with higher LVM (HR = 1.1/10 g, CI = 1.05–1. 12, p < 0.0001) and lower SV (HR = 0.90/10 mL, CI = 0.80–0.98; p < 0.01), with no independent effect of EF (HR = 0.90/10%, CI = 0.70–1.03, p = 0.11). Conclusion: Evaluation of LV pump performance is influenced by the amount of myocardial muscle pumping blood into the arterial tree. When LV mass is taken into consideration, indices of LV pump performance may be at least as good as ejection-phase indices of LV function for identification of subjects at risk of incident CV events.