Differences in Heart Rate Variability between Non-ST-Elevation Myocardial Infarction Patients with and without Type 2 Diabetes Mellitus

Abstract

Background: Variations in heart rate variability (HRV), indicative of potential life-threatening conditions, are associated with an increased risk of ventricular arrhythmias and sudden death. Patients with myocardial infarction (MI) and type 2 diabetes mellitus (T2DM) may also exhibit significant changes in HRV markers that are commonly associated with unfavorable outcomes.

Objective: We evaluated the differences in HRV features between Non-ST-elevation MI (NSTEMI) patients with and without T2DM.

Methods: This study included 88 individuals diagnosed with NSTEMI, with an average age of 58 years. The participants were divided into two groups: Group I, 39 patients with T2DM (59% men) and Group II, 49 patients without DM (53% men). The Myocard-Holter-2 device was used for 24-hour Holter monitoring from to 10-14 days of hospitalization. This study evaluated the daily mean HR and transient HRV markers, including SDNN, SDNNi, rMSSD, and pNN50.

Results: The two groups were similar in terms of sex and age (p=0.312 and p=0.338, respectively). Patients with T2DM had a higher average daily HR of 82±9/min compared to 75±8/min (p=0.002). Patients in group 1 had lower average values for all HRV time parameters, including SDNN (87.2±18.1 ms vs 89.2±10.6 ms, p=0.006), SDNNi (27.5±5.1 ms vs 43.7±6.3 ms, p=0.004), rMSSD (21.4±3.2 ms vs 19.8±2.6 ms, p<0.001), and pNN50 (6.2±2.8% vs 5.3±2.4%, p<0.001).

Conclusions: Patients with NSTEMI and T2DM had lower HRV scores, suggesting that they may be at a higher risk for developing non-life-threatening cardiac arrhythmias and experiencing cardiac autonomic neuropathy.