Heart rate-corrected QT interval prolongation as a prognostic marker for 3-year survival in people with Type 2 diabetes undergoing above-ankle amputation.

Abstract

To evaluate whether heart rate-corrected QT interval is a plausible prognostic factor for survival after major amputation in people with Type 2 diabetes. All people with Type 2 diabetes aged<80years who underwent a major amputation at two hospitals with multidisciplinary diabetic foot teams were evaluated and grouped according to whether their heart rate-corrected QT interval was ≤ or >440ms. A total of 70 patients with a median age of 72years were included in the study. During the 3years of follow-up, 38 patients (54%) died. Heart rate-corrected QT interval prolongation was present in 51.4% of the patients and was strongly associated with 3-year mortality (73 vs 36%; P<0.001). In a Cox proportional hazard model, heart rate-corrected QT interval prolongation was the strongest independent risk factor for 3-year mortality [hazard ratio 2.20 (95% CI 1.11-4.38)]. Treatment with metformin seemed to have a protective effect [hazard ratio 0.22 (95% CI 0.05-0.94)]. The findings of the present study indicate that heart rate-corrected QT interval prolongation is associated with increased mortality in people with Type 2 diabetes undergoing above-ankle amputation.