The Impact of Time Interval From Symptom Onset to Primary Coronary Angioplasty on Heart Rate Variability in Patients With ST-Elevation Myocardial Infarction: A Single-Center Study

Background and aims: Heart rate variability (HRV) is recognized as an independent risk factor for predicting sudden cardiac death in patients with coronary artery disease. The present study aimed to investigate the impact of the time interval between the onset of symptoms in patients experiencing ST-segment elevation myocardial infarction (STEMI) and the subsequent primary coronary angioplasty on HRV. Methods: A cross-sectional study was conducted involving 65 patients diagnosed with acute MI who were referred to Shahrekord Hajar University Hospital for primary coronary angioplasty. The angiographic findings of the patients, as well as electrophysiological data collected one week and one month post-acute MI, were reviewed and extracted by a cardiologist specializing in electrophysiology. Finally, the data were analyzed using SPSS. Results: The results demonstrated the right and left coronary arterial dominance in 96.8% and 1.3% of cases, respectively, while a co-dominant pattern was present in 1.3% of patients. The SDNN index and SDNN decreased one month after acute MI (P=0.396 and P=0.378, respectively). In contrast, the rMSSD and pNN50 indices showed slight increases (P=0.568 and P=0.847, respectively). The triangle index increased significantly (P<0.001), whereas the high-frequency index represented a decrease (P=0.282). Eventually, low-frequency and very low-frequency indices did not exhibit significant increases (P=0.102 and P=0.051, respectively). Conclusion: Changes in HRV indicators in patients with STEMI significantly differed when comparing data collected one week and one month after primary coronary angioplasty. While high levels of HRV are generally associated with optimal responsiveness of the cardiac autonomic nervous system, the present study’s findings do not support the prognostic value of this established electrophysiological principle.