Introduction: African Americans (AA) have a disproportionate greater burden of risk factors and higher risk of HF than Whites. However, the factors underlying the transition from at-risk to clinical HF in AA is not well understood. We aimed to examine the independent and joint effects of subclinical myocardial injury, as measured by highly sensitive assays for cardiac troponin (hs-TnI) and left ventricular hypertrophy (LVH), on risk of HF in AA.
Methods: Participants from the Jackson Heart Study, a prospective study of AA adults, without prevalent HF at baseline (2000-2004) were stratified into categories based on elevation in hs-cTnI (>6 ng/L) and presence of LVH (LV mass > 96 g/m2 in women and > 116 g/m2 in men). The risk of incident HF across different LVH and hs-cTnI groups was assessed using adjusted Cox models.
Results: We included 3,796 participants (54 y, 64% women, 17.2% with elevated hs-TnI & 6.1% with LVH) with median follow up of 9.8 y and 285 incident HF events. In adjusted analyses, LVH and higher hs-TnI at baseline were independently associated with risk of HF [HR (95% CI): LVH (vs. no LVH) = 2.2(1.6 - 2.9); Log hs-cTnI (per unit higher)=1.6(1.5 - 1.8)]. A significant interaction was observed between LVH and hs-TnI for the risk of HF (p-int < 0.0001) with the highest risk among individuals with both LVH and elevated hs-TnI [43% incidence, HR (95% CI): 5.7(3.9 - 8.2)]. In contrast, LVH in absence of hs-TnI elevation was not associated with HF risk [Figure]. Among 2,367 participants with repeat assessment of hs-TnI at 5 year follow-up, increase in hs-TnI levels on follow-up was also associated with significantly higher risk of HF [HR (95% CI) per 1 unit increase = 1.03 (1.02 - 1.06)]
Conclusions: The combination of LVH and elevated hs-TnI levels identifies a malignant preclinical HF phenotype in AAs with a remarkably high absolute risk of HF over a 10-year f/u period. Longitudinal increase in hs-TnI levels is also associated with significant risk of HF. Targeting these high-risk subsets may be an important strategy to mitigate HF risk in blacks.