Association between reduced myocardial contraction fraction and cardiovascular disease outcomes: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: The myocardial contraction fraction (MCF: stroke volume to myocardial volume) is a volumetric measure of left ventricular myocardial shortening. We examined the relationship of MCF, measured by cardiac magnetic resonance imaging (cMRI), to incident cardiovascular (CV) events within the Multi-Ethnic Study of Atherosclerosis (MESA).
METHODS: Participants (n = 5000, aged 45-84 years) underwent cMRI. PRIMARY OUTCOME: CVD events (myocardial infarction, resuscitated cardiac arrest, stroke, coronary heart disease: CHD death, and stroke death). SECONDARY OUTCOMES: CHD and heart failure (HF) events. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95% confidence intervals (CI) for outcomes.
RESULTS: There were 299 incident CVD, 188 CHD, and 151 HF events over 10.2 years. The lowest MCF quartile was associated with an increased risk for incident CVD [HR 2.42, CI: 1.58-3.72], CHD [HR 2.32, CI: 1.36-3.96] and HF events [HR 1.99, CI: 1.15-3.44]. In a model adjusted for demographics, CV risk factors, antihypertensive and lipid-lowering medication use, each standard deviation decrease in MCF was associated with incident CVD [HR 1.42, CI: 1.23-1.64], CHD [HR 1.40, CI: 1.17-1.67] and HF [HR 1.58, CI: 1.30-1.94]. In a subgroup analysis of participants with preserved ejection fraction and without left ventricular hypertrophy, the lowest MCF quartile and each standard deviation decrease in MCF was also associated with an increased risk for incident CVD in fully-adjusted analyses.
CONCLUSIONS: MCF is a novel measure that can be measured using cMRI. In this multi-ethnic cohort, MCF is a measure that can be used to predict incident CVD events.