Type 2 Diabetes in Ischemic Heart Disease With Heart Failure

Ischemic heart disease is one of the most common risk factors for heart failure (HF) development in patients with type 2 diabetes, according to research published in the Journal of the American College of Cardiology.

Investigators from the Karolinksa Institute and KTH Royal Institute of Technology in Stockholm,  and Linköping University in Linköping, Sweden sought to examine the impact of ischemic and nonischmic HF as well as previous revascularization on long-term prognosis in patients with and without type 2 diabetes.

Patient data were collected from the Swedish Heart Failure Registry (SwedeHF) database, including 65 hospitals and 113 outpatient clinics. SwedeHF data from 36,595 patients with HF, collected between 2003 and 2011, was used to establish the current study cohort of 35,163 patients (68% from hospitals, 32% from outpatient clinics). Patients were stratified by their diabetes status, ischemic or nonischemic HF, and history of revascularization. The primary study end point was all-cause mortality.

The researchers found that patients with type 2 diabetes were younger, and 90% had 1 or more associated comorbidities. Ischemic heart disease was present in 62% of patients compared with 47% of patients without type 2 diabetes; 53% and 48% of these patients, respectively, had previously undergone revascularization.

Patients with both type 2 diabetes and ischemic heart disease were found to have the highest mortality rates, accentuated by the absence of previous revascularization (adjusted hazard ratio [HR]: 0.82 in favor of such treatment; 95% confidence interval [CI]: 0.75-0.91). Revascularization did not diminish the impact of type 2 diabetes, which predicted mortality in those both with and without revascularization history (HR: 1.36; 95% CI: 1.24-1.48 and HR: 1.45; 95% CI: 1.33-1.56, respectively).

In patients with type 2 diabetes who had undergone previous revascularization, comorbidities—including atrial fibrillation, pulmonary disease, and preserved left ventricular ejection fraction (LVEF)—were less common. Among patients with ischemic heart disease who also had type 2 diabetes had similar preserved LVEF (≥50%), as patients without diabetes, but were more symptomatic (New York Heart Association functional class III or IV; 54% vs 46%).

The researchers found that 50% of the ischemic heart disease patients had a history of revascularization—which was more common in patients with type 2 diabetes than without (53% vs 48%, respectively). By the conclusion of the study, 40% of the total patient population had died; 46% of whom had type 2 diabetes and 38% who did not.

“Type 2 diabetes remained an independent mortality predictor among revascularized ischemic heart disease patients, as well as in patients without previous revascularization,” the authors wrote.

Regardless of ischemic or noischemic HF, patients with type 2 diabetes have a higher mortality risk, and previous revascularization is associated with improved prognosis compared with patients without revascularization.

“Randomized trials are needed to validate these observational data and confirm the impact of revascularization in patients with type 2 diabetes and HF,” the researchers concluded.

Strengths and Limitations

• The size and unselected nature of the population is a strength of the study as it reflects “contemporary, everyday clinical practice.”
• Limitations include the possibility of varying diagnostic criteria within registry data, as well as a possible underestimation of the number of patients with type 2 diabetes
• In addition, the researchers did not have details about the duration of patients’ diabetes nor class of glucose-lowering therapy, factors with known prognostic implications.

Disclosures: Dr Dahlstrom has received research grants from Linköping University and AstraZeneca, as well as honoraria from multiple pharmaceutical companies, none of which were directly related to this study. Dr Ryden has received research grants from the Swedish Heart-Lung Foundation, AFA Insurance, and the Swedish Diabetes Foundation, honorarira from expert group participation, and personal fees for lectures organized by pharmaceutical and societal organizations unrelated to the present study. Dr Norhammar has received honoraria for advisory boards and lectures from Eli Lilly, AstraZeneca, MSD, and Boehringer Ingelheim.

Reference

Johansson I, Dahlström U, Edner M, Nasman P, Rydén L, Norhammar A. Prognostic implications of type 2 diabetes mellitus in ischemic and nonischemic heart failure. J Am Coll Cardiol. 2016;68(13):1404-1416. doi: 10.1016/j.jacc.2016.06.061.