Prevalence and predictors of severe autonomic failure in patients with insulin-dependent type 2 diabetes mellitus and coronary artery disease: pilot study

BackgroundPresence of severe autonomic failure (SAF), defined as coincidence of abnormal heart rate turbulence and abnormal deceleration capacity, identifies a group of patients with very poor prognosis among post-infarction patients with diabetes mellitus. However, factors contributing to development of SAF are entirely unknown. Here, we aimed to identify clinical, biochemical, and hemodynamic factors predicting SAF in a consecutive cohort of diabetic patients with coronary artery disease (CAD).MethodsBetween January 2010 and July 2011, we prospectively enrolled 97 patients with insulin-dependent type 2 diabetes mellitus and stable CAD in sinus rhythm. Heart rate turbulence (as marker of autonomic reflex activity) and deceleration capacity (as marker of autonomic tonic activity) were calculated from 24-hour Holter recordings. Uni- and multivariable logistic regression analysis included duration of diabetes mellitus, diabetic neuropathy, retinopathy, nephropathy, level of HbA1c, left ventricular ejection fraction (LVEF), brain natriuretic peptide, presence of multivessel disease, and history of myocardial infarction.ResultsTen (10.3%) of the 97 patients exhibited signs of SAF. Patients with SAF were characterized by longer duration of diabetes (25 years vs 15 years), higher prevalence of diabetic neuropathy (70% vs. 36%), retinopathy (80% vs 45%) and nephropathy (90% vs 55%), significantly higher levels of HbA1c (9.0% vs 7.4%; P = .002) and a lower LVEF (30% vs.55%; P = .001). On multivariable analysis, LVEF ≤ 35% and HbA1c > 8% were the only factors which were independently associated with SAF (odds ratios of 23.1 [95% CI, 1.8-287.0]; P = .015 and 6.6 [1.1-40.1]; P = .043).DiscussionIn patients with insulin-dependent type 2 diabetes mellitus and CAD, presence of SAF correlates with both glycemic control and diabetic complications. Impaired LVEF and increased level of HbA1c were independently associated with SAF.