Incidence of Heart Failure among Diabetic Patients with Ischemic Heart Disease: A Cohort Study

Abstract Background In population studies of heart failure (HF), diabetes was shown to be an independent risk factor but the evidence regarding Diabetes Mellitus (DM) having incremental effect in incidence of HF in patients with ischemic heart disease (IHD) is scarce. Our study aimed to assess the incidence of HF in diabetic IHD patients compared to non-diabetic IHD patients. Methods A retrospective cohort study was conducted among 306 patients with IHD followed-up at Tikur Anbessa Specialized Hospital in Addis Ababa, Ethiopia. The IHD patients who did not have HF at baseline were followed for 24 months beginning from November 30, 2015. We assessed the incidence of HF in patients with diabetic IHD versus the non-diabetic IHD. Cox proportional hazards models were used to assess the association between diabetic IHD and HF after controlling for important covariates. Results Mean age was 56.8 years and male patients accounted for 69%. Prevalence of DM was 31.4% (n=96). During the 24 months follow-up period, 196 (64.1%) had incident HF. Predictors of incident HF were female sex [COR 2.2(1.3-3.8), p=0.006], DM [COR 1.8 (1.1-3.0), p = .04], older age [t (304) = 2.5, p = 0.01, two tailed], bigger left atrial size [t (196) = 2.9, p = 0.005, two-tailed], and lower hemoglobin [t (232) = - 2.3, p = 0.02, two-tailed]. On multivariate Cox regression, DM was significantly associated with incident HF [Hazard Ratio = 2.04, 95% CI: 1.32-3.14, p = 0.001]. Furthermore, when the patients were stratified by hypertension (HTN), DM was associated with worse prognosis, the strongest association being in those with co-existing DM and HTN [HR = 2.57,95% CI =1.66-3.98, p<0.0001] followed by the presence of DM without HTN [HR 2.27, 95% CI = 1.38-3.71, p=0.001]. Conclusion DM is the strongest predictor of incident HF in patients with IHD. It is worse when DM is combined with HTN.