Obesity Paradox and Risk of Sudden Death in HF
Background Among patients with heart failure (HF), body mass index (BMI) has been inversely associated with mortality, giving rise to the so-called obesity paradox. The aim of this study was to examine the relationship between BMI and two modes of cardiac death: pump failure death and sudden death.
Methods Nine hundred seventy-nine patients with mild to moderate chronic symptomatic HF from the MUSIC (MUerte Subita en Insuficiencia Cardiaca) Study, a prospective, multicenter, and longitudinal study designed to assess risk predictors of cardiac mortality, were followed up during a median of 44 months. Independent predictors of death were identified by a multivariable Cox proportional hazards model.
Results Higher BMI emerged as an independent predictor of all-cause mortality (hazard ratio [HR] = 0.94, 95% confidence interval [CI] = 0.91–0.97, P = .0003) and pump failure death (HR = 0.93, 95% CI = 0.88–0.98, P = .004). Sudden death accounted for 45% of deaths in obese patients, 53% in overweight patients, and 37% in lean patients. No significant relationship between BMI and sudden death was observed (HR = 0.97, 95% CI = 0.92–1.02, P = .28). The only independent predictors of sudden death were prior history of myocardial infarction (HR = 1.89, 95% CI = 1.23–2.90, P = .004), hypertension (HR = 1.66, 95% CI = 1.05–2.63, P = .03), left ventricular ejection fraction (HR = 0.88, 95% CI = 0.79–0.96, P = .006), and N-terminal pro–B-type natriuretic peptide (HR = 1.01, 95% CI = 1.00–1.02, P = .048).
Conclusions The obesity paradox in HF affects all-cause mortality and pump failure death but not sudden death. The risk of dying suddenly was similar across BMI categories in this cohort of ambulatory patients with HF.
Obesity is a problem that is reaching unprecedented proportions both in wealthy countries and in developing nations. Considering patients as a function of their body mass index (BMI), nearly 70% of adults in the United States are classified as overweight or obese, with data suggesting that this growing problem will be expected to lead to higher rates of cardiovascular disease with the passage of time. Obesity is a well-known risk factor for the development of heart failure (HF). Surprisingly, for reasons that remain unclear, obese patients with HF have a better prognosis than normal-weight patients, giving rise to the so-called obesity paradox. Indeed, although obesity is clearly associated with more advanced cardiovascular disease and several studies indicate a progressive increase in all-cause mortality and years of life lost associated with obesity, recent studies have focused on the apparent paradox regarding the relationship between obesity and HF. Kenchaiah et al, in the CHARM cohort, demonstrated that patients with the lowest mortality rates were those with a BMI between 30.0 and 34.9 kg/m, a progressive increase in mortality was evident below this range, and a plateau or increase was observed above this range (U- or J-shaped association).
The obesity paradox in HF has been mainly studied for all-cause mortality, and the possibility that extreme leanness could be the expression of malignant non-cardiac diseases has been ruled out. Limited data about the effects of increasing BMI on pump failure death and sudden death, the two main modes of cardiac death in HF, exist.
We aimed to assess the prognostic value of BMI in a large cohort of patients with HF, independently of other strong predictors of mortality, and to assess the relationship between BMI, pump failure death, and sudden death.
Abstract and Introduction
Abstract
Background Among patients with heart failure (HF), body mass index (BMI) has been inversely associated with mortality, giving rise to the so-called obesity paradox. The aim of this study was to examine the relationship between BMI and two modes of cardiac death: pump failure death and sudden death.
Methods Nine hundred seventy-nine patients with mild to moderate chronic symptomatic HF from the MUSIC (MUerte Subita en Insuficiencia Cardiaca) Study, a prospective, multicenter, and longitudinal study designed to assess risk predictors of cardiac mortality, were followed up during a median of 44 months. Independent predictors of death were identified by a multivariable Cox proportional hazards model.
Results Higher BMI emerged as an independent predictor of all-cause mortality (hazard ratio [HR] = 0.94, 95% confidence interval [CI] = 0.91–0.97, P = .0003) and pump failure death (HR = 0.93, 95% CI = 0.88–0.98, P = .004). Sudden death accounted for 45% of deaths in obese patients, 53% in overweight patients, and 37% in lean patients. No significant relationship between BMI and sudden death was observed (HR = 0.97, 95% CI = 0.92–1.02, P = .28). The only independent predictors of sudden death were prior history of myocardial infarction (HR = 1.89, 95% CI = 1.23–2.90, P = .004), hypertension (HR = 1.66, 95% CI = 1.05–2.63, P = .03), left ventricular ejection fraction (HR = 0.88, 95% CI = 0.79–0.96, P = .006), and N-terminal pro–B-type natriuretic peptide (HR = 1.01, 95% CI = 1.00–1.02, P = .048).
Conclusions The obesity paradox in HF affects all-cause mortality and pump failure death but not sudden death. The risk of dying suddenly was similar across BMI categories in this cohort of ambulatory patients with HF.
Introduction
Obesity is a problem that is reaching unprecedented proportions both in wealthy countries and in developing nations. Considering patients as a function of their body mass index (BMI), nearly 70% of adults in the United States are classified as overweight or obese, with data suggesting that this growing problem will be expected to lead to higher rates of cardiovascular disease with the passage of time. Obesity is a well-known risk factor for the development of heart failure (HF). Surprisingly, for reasons that remain unclear, obese patients with HF have a better prognosis than normal-weight patients, giving rise to the so-called obesity paradox. Indeed, although obesity is clearly associated with more advanced cardiovascular disease and several studies indicate a progressive increase in all-cause mortality and years of life lost associated with obesity, recent studies have focused on the apparent paradox regarding the relationship between obesity and HF. Kenchaiah et al, in the CHARM cohort, demonstrated that patients with the lowest mortality rates were those with a BMI between 30.0 and 34.9 kg/m, a progressive increase in mortality was evident below this range, and a plateau or increase was observed above this range (U- or J-shaped association).
The obesity paradox in HF has been mainly studied for all-cause mortality, and the possibility that extreme leanness could be the expression of malignant non-cardiac diseases has been ruled out. Limited data about the effects of increasing BMI on pump failure death and sudden death, the two main modes of cardiac death in HF, exist.
We aimed to assess the prognostic value of BMI in a large cohort of patients with HF, independently of other strong predictors of mortality, and to assess the relationship between BMI, pump failure death, and sudden death.
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