AbstractAimsWe aim to evaluate the association of frailty and high body mass index with risk of incident heart failure.Methods and resultsFrom the Kuopio Ischaemic Heart Disease Risk Factor Study, 408 women and 369 men, aged 61–74 years were included in this study. Frailty was ascertained with the presence of 3–5 and prefrailty 1–2 of the following criteria: weight loss (highest 20% over 7 years), self‐reported tiredness, weakness (measured by handgrip strength), slow walking speed (walking pace), and low physical activity (lowest 20%). At the baseline, participants were allocated to frail (n = 36), prefrail (n = 340), and robust (n = 441). HF incidents were obtained by record linkages from the national hospitalization registry in Finland up to 31 December 2019. Multivariate Cox proportional hazards regression estimated the hazard ratio (HR) of incident events, adjusted for potential confounders. Two hundred one HF events were recorded (111 in women and 90 in men) during the 14.2 years follow‐up. After adjustment for the age and sex, the risk of HF events was higher among prefrail (HR 1.42, 95% CI 1.08 to 1.79, P = 0.02) and frail (HR 3.39, 95% CI 1.89 to 4.79, P ≤ 0.001) compared with the robust group. After adjusting for multiple confounders result remained significant for HF indecent in prefrail [1.46 (HR 1.46, 95% CI 1.09 to 1.95, P = 0.01] and frail (HR 3.33, 95% CI 1.86 to 5.70, P ≤ 0.001). In the sensitivity analysis, significant interaction between high BMI (≥25 kg/m²) and frailty was observed (P for interaction = 0.02). The association of frailty [multivariate‐adjusted HR: 2.88 (1.56 to 5.33), P ≤ 0.001)] and prefrailty [multivariate‐adjusted HR: 1.40 (1.08 to 1.91), P = 0.03)] with risk of HF indecent was more pronounced in those with high BMI.ConclusionsFrailty is highly common in older age, and our results indicated the high risk of HF incident in frail and prefrail groups. While frailty is clinically recognized by weight loss phenotype, our finding showed that frailly and high BMI can coexist and worsen the risk of HF incidence. Further research is warranted to substantiate these results in large studies and clinical settings.