Fitness, Obesity, Heart Failure Risk in Diabetes Mellitus

Study Questions:

What is the impact of a lifestyle intervention and changes in cardiorespiratory fitness (CRF) and body mass index (BMI) on risk for heart failure (HF)?

Methods:

The study cohort was comprised of participants from the Look AHEAD (Action for Health in Diabetes) trial without prevalent HF. The primary outcomes of interest were incidence of overall HF, HF with preserved ejection fraction (HFpEF), and HF with reduced EF (HFrEF). The study authors utilized time to event analyses to compare the risk of incident HF between the intensive lifestyle intervention (ILI) versus diabetes support and education (DSE) groups. The authors utilized multivariable adjusted Cox models to evaluate associations of baseline measures of CRF estimated from a maximal treadmill test, BMI, and longitudinal changes in these parameters with risk of HF.

Results:

The study authors found that among the 5,109 trial participants, over a median follow-up of 12.4 years (58,094 person-years [PY]), 257 incident HF events occurred (event rate per 1,000 PY, 4.42), of which 50.2% (n = 129) were HFpEF (event rate per 1,000 PY, 2.23), 40.5% (n = 104) were HFrEF (event rate per 1,000 PY, 1.79), and 9.3% (n = 24) were HF with missing left ventricular EF. There was no significant difference in the risk of incident HF between the ILI versus DSE groups (hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.75-1.23). In the most adjusted Cox models, the risk of HF was 39% and 62% lower among moderate fit (Tertile 2: HR, 0.61; 95% CI, 0.44-0.83) and high fit (Tertile 3: HR, 0.38; 95% CI, 0.24-0.59) groups, respectively (reference group: low fit, Tertile 1). Among HF subtypes, after adjustment for traditional cardiovascular risk factors and interval incidence of myocardial infarction, baseline CRF was not significantly associated with risk of incident HFrEF. In contrast, the risk of incident HFpEF was 40% lower in moderate fit and 77% lower in the high fit groups. Baseline BMI was also not associated with risk of incident HF, HFpEF, or HFrEF after adjustment for CRF and traditional cardiovascular risk factors. Among participants with repeat CRF assessments (n = 3,902), improvements in CRF and weight loss over 4-year follow-up was significantly associated with lower risk of HF (per 10% increase in CRF = 0.90; 95% CI, 0.82-0.99, per 10% decrease in BMI, HR, 0.80; 95% CI, 0.69-0.94).

Conclusions:

The authors concluded that among participants with type 2 diabetes mellitus in the Look AHEAD trial, the ILI did not appear to modify the risk of HF. Higher baseline CRF and sustained improvements in CRF and weight loss were associated with lower risk of HF.

Perspective:

This study suggests that low CRF may identify individuals with type 2 diabetes mellitus who are at higher risk for developing HF and that intentional weight loss and sustained improvements in CRF may significantly lower the risk of incident HF. But lifestyle intervention strategies with modest improvements in CRF and weight loss may not be sufficient to lower the risk of HF. Prospective studies with more intense interventions targeting substantial weight loss and CRF improvement are required to evaluate the role of lifestyle interventions in modifying HF risk and whether indeed the old adage ‘survival of the fittest’ is true.

Clinical Topics: Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Prevention, Sports and Exercise Cardiology, Acute Heart Failure, Sports and Exercise and ECG and Stress Testing

Keywords: Body Mass Index, Diabetes Mellitus, Type 2, Exercise Test, Heart Failure, Life Style, Metabolic Syndrome X, Myocardial Infarction, Obesity, Overweight, Physical Fitness, Primary Prevention, Risk Factors, Stroke Volume, Weight Loss


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