Heart rate turbulence can predict cardiac mortality following myocardial infarction in patients with diabetes mellitus.

BACKGROUND

Previous studies have described the clinical utility of heart rate turbulence (HRT) as an autonomic predictor in risk-stratifying patients after myocardial infarction (MI). Some reports showed that diabetes mellitus (DM) affects the prognostic value of autonomic markers. We assessed the utility of HRT as a risk marker in post-MI patients with DM and without DM.

METHODS

We prospectively enrolled 231 consecutive DM patients and 300 non-DM patients after acute MI. HRT was measured using an algorithm based on 24-hour Holter electrocardiograms (ECGs), assessing 2 parameters: turbulence onset (TO) and turbulence slope (TS). HRT was considered positive when both TO ≥0% and TS ≤2.5 ms/R-R interval were met. The endpoint was defined as cardiac mortality.

RESULTS

Of patients with DM, 9 patients (4%) were not utilized for HRT assessment because of frequent ventricular contractions or presence of atrial fibrillation. Forty-two of 222 patients (19%) were HRT positive. During follow-up of 876 ± 424 days, 26 patients (22%) reached the endpoint. Several factors including left ventricular ejection fraction (LVEF), renal dysfunction, documentation of nonsustained ventricular tachycardia (VT), and a HRT-positive outcome had significant association with the endpoint. Multivariate analysis determined that renal dysfunction and a positive HRT outcome had significant value with a hazard ratio (HR) of 4.7 (95%CI, 1.9-11.5; P = 0.0008) and 3.5 (95%CI, 1.4-8.8; P = 0.007), respectively. In non-DM patients, only a positive HRT outcome had significant value.

CONCLUSIONS

This study reveals that HRT detected by 24-hour Holter ECG can predict cardiac mortality in post-MI patients whether DM is present or not.