Introduction: Patients with type 2 diabetes mellitus (T2DM), have significantly higher risk of cardiovascular events, including heart failure (HF). Cardiorespiratory fitness (CRF) has been shown to favorably modify comorbidities of HF and lower the risk of HF. However, the independent effect of CRF on HF incidence in patients with T2DM has not been assessed.
Methods: We identified 6,263 patients (aged 58.1+10.0 years) with T2DM and no HF or evidence of ischemia prior to an exercise treadmill testing (ETT). We established four fitness categories, based on age-stratified quartiles of peak metabolic equivalents (METs) achieved Least-Fit (4.7±1.1 METs; n= 1,547); Low-Fit (6.6±1.2 METs; n=2,104) Moderate-Fit (8.0±1.3 METs; n=1,454) and Fit (10.9±2.3 METs; n=1,160). Cox proportional hazards model was constructed to assess HF incidence risk associated with exercise capacity. The model was adjusted for age, BMI, race, comorbidities, and medications. The Least-Fit category served as the reference group. P-values <0.05 using two sided tests were considered statistically significant for all test.
Results: During a follow-up of 12.9+7.1 years, 1,429 or 21.5% of these patients developed HF accounting for 13.5 events per 1,000 person-years of observation. The CRF-CHF risk association was inverse and graded. Risk decreased by 16% (HR: 0.84; CI: 0.82-0.87; p<0.001) for each 1-MET increase in CRF. When CRF categories were considered, HF risk declined progressively by 38% (HR: 0.62; CI: 0.55-0.71; p<0.001) for those in the Low-Fit; 49% in the Moderate-Fit (HR: 0.51; CI: 0.44-0.59; p<0.001), and 64% (HR: 0.36; CI: 0.30-0.43; p<0.001) for individuals in the Fit category.
Conclusions: High levels of CRF were protective against HF incidence in Veterans with T2DM. The CRF-HF association was graded and independent of other risk factors.
C. Faselis: None. J.N. Myers: None. P. Narayan: Research Support; Self; AstraZeneca, Eli Lilly and Company. P. Karasik: None. H. Moore: None. A. Ahmed: None. H.M. Sheriff: None. E. Nylen: None. P. Kokkinos: None.