Ischemic heart disease linked to worse prognosis in heart failure patients with type 2 diabetes
Mortality risk was highest in patients who had both type 2 diabetes and ischemic heart disease and had not had previous revascularization.
Ischemic heart disease is associated with poor prognosis in heart failure patients with type 2 diabetes, according to a recent study.
Researchers in Sweden used data from a national heart failure registry to examine the effect of ischemic and nonischemic heart failure and prior revascularization on long-term prognosis in patients with type 2 diabetes mellitus. Patients in the registry were stratified by diabetes status, ischemic or nonischemic heart failure, and history of revascularization from 2003 to 2011 and were followed for predictors of death and longevity for a range of 0 to 8.7 years (median, 1.9 years). The study's primary end point was all-cause mortality. Results were published online Sept. 19 by the Journal of the American College of Cardiology.
A total of 35,163 patients with heart failure were included in the study. Of these, 24.4% had type 2 diabetes and 75.6% did not. Those who had type 2 diabetes tended to be younger than those without (75 years vs. 77 years), and almost all of those with type 2 diabetes (90%) had at least 1 associated comorbid condition. Sixty-two percent of patients with type 2 diabetes had ischemic heart disease versus 47% of patients without type 2 diabetes. Of these groups, 53% and 48%, respectively, had previously had revascularization.
By the end of the study, 14,144 patients (40%) had died, 3,950 (46%) of those with type 2 diabetes and 10,194 (38%) of those without. In patients with type 2 diabetes, adjusted hazard ratios for death were 1.40 (95% CI, 1.33 to 1.46) in those with ischemic heart disease and 1.30 (95% CI, 1.22 to 1.39) in those without. Mortality risk was highest in patients who had both type 2 diabetes and ischemic heart disease and had not had previous revascularization. Type 2 diabetes predicted death in patients with and those without a history of revascularization (adjusted hazard ratios, 1.36 [95% CI, 1.24 to 1.48] and 1.45 [95% CI, 1.33 to 1.56], respectively).
The authors noted that diagnostic criteria could have varied in the registry data and that patient history was not always complete. They also pointed out that no data were available on silent angina and on certain diabetes variables and stressed that the assumptions made about revascularization should be considered hypothesis-generating due to retrospective data and lack of randomization. However, they concluded that type 2 diabetes is associated with greater risk for all-cause mortality in patients with ischemic and nonischemic heart failure, that previous revascularization is associated with better survival, and that most patients with type 2 diabetes and nonischemic heart failure have at least 1 treatable comorbid condition associated with heart failure risk.
The study shows that type 2 diabetes is a “very relevant risk factor” in heart failure patients, since it remained a predictor of mortality regardless of whether ischemic heart disease was present, and provides “a clear message” that heart failure patients with type 2 diabetes should undergo careful evaluation for revascularization potential, said an accompanying editorial.
The editorialists also pointed out the limitations of the registry data, including the potential that a significant proportion of patients may have had heart failure with preserved ejection fraction and that data were missing on New York Heart Association class and ejection fraction. They called for more research to determine whether and how ischemia predicts outcomes of revascularization in this patient population, as well as randomized, controlled trials to verify the current study's results.