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

Background

Presence 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).

Methods

Between 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 HbA_1c, left ventricular ejection fraction (LVEF), brain natriuretic peptide, presence of multivessel disease, and history of myocardial infarction.

Results

Ten (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 HbA_1c (9.0% vs 7.4%; P = .002) and a lower LVEF (30% vs.55%; P = .001). On multivariable analysis, LVEF ≤ 35% and HbA_1c > 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).

Discussion

In 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 HbA_1c were independently associated with SAF.