Assessment of impact of low-flow state on long-term outcome in multiethnic population using cardiac magnetic...

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 low-flow state (LFS) on all-cause mortality in multiethnic population, we analyzed 4,398 asymptomatic participants without clinical cardiovascular disease undergoing cardiac magnetic resonance (CMR) in the multiethnic study of atherosclerosis. LV stroke volume index (SVi), LV ejection fraction (LVEF), and myocardial contraction fraction (MCF) were measured. LV flow states were classified as normal flow state (NFS: SVi > 35 mL/m²), low-flow state (LFS, 30-34 mL/m²), and very low-flow state (VLFS: SVi < 30 mL/m²). Clinical data were collected at enrollment. Participants were followed up for a median of 14.2 yr. All-cause and cardiovascular disease mortalities were used as primary endpoints. All-cause mortality was 16.2%, and cardiovascular disease mortality was 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 33.5 mL/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% confidence interval (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. LFS was significantly associated with increased all-cause mortality despite normal LVEF and no valvular disease.NEW & NOTEWORTHY This is the first study demonstrating that low-flow state (LFS) has a significant impact on mortality in multiethnic study of atherosclerosis (MESA) participants with no valvular disease. The study may have a clinical implication since LFS is commonly present in multiethnic population. The current study provides new information on clinical characteristics and myocardial performance of LFS suggesting that further prospective studies to determine whether targeting modifiable risk factors for cardiovascular disease and metabolic syndrome would have any favorable impact on LFS.