Assessment of Impact of Low Flow State on Long-Term Outcome in Multi-Ethnic Population Using Cardiac Magnetic Resonance

Left ventricular (LV) flow state is associated with unfavorable outcome in patient with severe aortic stenosis. However, there is little information on its impact on long-term prognosis in a population without valvular disease. To examine the impact of LFS on all-cause mortality in multi-ethnic population we analyzed 4398 asymptomatic participants without clinical cardiovascular disease undergoing cardiac magnetic resonance (CMR) in the Multi-Ethnic Study of Atherosclerosis. LV stroke volume index (SVi), LVEF and myocardial contraction fraction (MCF) were measured. LV flow states were classified as normal flow state (NFS, SVi >35 ml/m 2 ), low-flow state (LFS, 30-34 ml/m 2 ) and very low-flow state (VLFS: SVi <30 ml/m 2 ). Clinical data were collected at enrollment. Participants were followed up for a median of 14.2 years. All-cause and cardiovascular disease mortalities were used as primary endpoints. All-cause mortality was 16.2% and cardiovascular disease mortality 3.5%. VLFS and LFS groups had more cardiovascular risk factors and lower cardiac performance than NFS. The relationship between all-cause mortality and SVi was “L-shape with the “breakpoint” at 33.5ml/m2 for a statistical significance (p=0.009). All-cause mortality was significantly associated with LFS after adjusted for age, sex, LVEF, and LV mass index with hazard ratio (HR) 1.81, 95% CI: 1.31-2.49 for VLF and HR: 1.21, 95% CI: 0.95-1.54 for LFS with overall p value 0.001). The highest cardiovascular disease mortality was seen in VLFS.