Abstract 9614: Association Between Myocardial Contraction Fraction and Heart Failure Subtypes in the Multi-Ethnic Study of Atherosclerosis (MESA)

Abstract

Introduction: Myocardial contraction fraction (MCF) is a non-ejection fraction volumetric measure of myocardial shortening which has been associated with incident heart failure (HF) including in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort. However, less is known regarding MCF’s prediction of HF subtypes. Methods: This analysis included men and women aged 45-84 free of clinical cardiovascular disease who underwent cardiac magnetic resonance imaging (cMRI) during the baseline MESA examination and who had data regarding incident adjudicated definite or probable HF events. MCF was calculated using cMRI measurements and defined as the ratio of stroke volume to myocardial volume. HF subtypes were divided into HF with ejection fraction (EF) < 50% (HF EF < 50%, including HF with reduced EF (EF ≤ 40%) and HF with mildly reduced EF (EF 41-49%) and HF with preserved EF (HFpEF, EF ≥ 50%). Cox proportional hazards regression was used to examine the association between MCF and incident HF subtype per decile increase in MCF. Event time was defined as time of first defined HF subtype, and censoring occurred at death or end of follow-up. After an incident HF event, participants were not at risk for another HF subtype. Covariates adjusted for were age, gender, race-ethnicity, education, body-mass index, tobacco and alcohol use, systolic blood pressure (BP), diabetes, physical activity, total cholesterol, and BP and lipid lowering drug use. Results: Among 4,983 participants (mean age 61, 52% female, 61% non-White) over a maximum of 18 years follow-up, there were 275 incident HF events (142 HF EF < 50%, 113 HFpEF, 20 unknown EF). MCF differed across HF status (p<0.001) . Participants without incident HF had a higher mean MCF (0.65) compared to HFpEF (0.62), HF EF < 50% (0.53), and unknown EF (0.52). The adjusted risk of any HF was reduced (HR 0.86, 95% CI 0.82, 0.91) per decile increase of MCF. MCF was strongly associated with incident HF EF < 50% (adjusted HR 0.80, CI 0.74, 0.86) but was not associated with HFpEF (adjusted HR 0.98, CI 0.91, 1.05). Conclusions: In a multi-ethnic cohort, increasing MCF is associated with a decreased risk of incident HF EF<50%. MCF is not significantly associated with incident HFpEF, suggesting different etiologic pathways for these two HF subtypes.