Abstract 2829: Decreased Left Ventricular Myocardial Contraction Fraction Predicts Excess Cardiovascular Morbidity and Mortality Despite Normal Ejection Fraction
INTRODUCTION: Myocardial contraction fraction (MCF) is the ratio of left ventricular (LV) stroke volume to myocardial volume and may serve as a measure of appropriateness of LV mass. We sought to determine whether depressed MCF predicts major adverse cardiovascular events (MACE) in healthy adults.
METHODS: 318 Framingham Heart Study (FHS) Offspring cohort members (60±9 yrs, 158 men) underwent cardiovascular magnetic resonance (CMR) imaging in 1998–1999. Subjects were free of clinical cardiovascular disease and were recruited from equal strata of age, sex and quintile of Framingham Coronary Risk Score (FCRS), with double sampling of the top quintile. LV and myocardial volumes were determined from volumetric breathold-cine SSFP CMR datasets. MACE were: CV death, myocardial infarction (MI), stroke or new heart failure (HF). A Cox proportional hazards model adjusting for FCRS was used to estimate hazard ratio (HR) for MACE in the lowest within-sex quartile (Q1) of MCF vs. other quartiles (Q2– 4). Kaplan-Meier (KM) plot and logrank test were used to compare event-free survival.
RESULTS: MCF was greater in women (0.58±0.13) than men (0.52±0.11), p<0.01. Over median 5.2-yr follow up there were 38 MACE (4 deaths, 14 MIs, 12 strokes, 8 HF) among 31 subjects. In this initially healthy cohort, EF (women: 0.72±0.07, men: 0.69±0.09) was not predictive of MACE. The HR for Q1 MCF was 2.7 [95% CI = 1.3–5.6]. The KM plot demonstrated lower event-free survival for Q1 MCF, p=0.0034.
CONCLUSIONS: In a cohort of adults without clinical cardiovascular disease, an MCF in the lowest quartile was associated with up to fivefold increased hazard of MACE over >5-year follow up, but Q1 LVEF was not predictive of MACE.