Cor Vasa 2026, 68(1):39-42

Autonomic Nervous System Imbalance Reflected by Reduced Heart Rate Variability in Patients with Coronary Slow Flow

Okan Tanriverdi
Department of Cardiology, Adiyaman Education and Research Hospital, Adiyaman, Turkey

Background: Coronary slow flow (CSF) is an angiographic entity characterized by delayed contrast progres- sion in coronary arteries without significant epicardial obstruction. Autonomic dysregulation has been sug- gested as a potential contributor to its pathophysiology. Heart rate variability (HRV) is a validated, non-invasive tool for assessing autonomic function.

Objective: To evaluate alterations in HRV parameters among patients with CSF and to explore the potential role of autonomic nervous system imbalance in its pathogenesis.

Methods: This cross-sectional study included 50 patients with CSF and 50 age- and sex-matched controls with normal coronary flow. Coronary flow was assessed using corrected TIMI frame count (cTFC). HRV parameters were derived from 24-hour Holter ECG monitoring and analyzed in both time and frequency domains.

Results: Baseline clinical and laboratory characteristics did not differ significantly between groups (p >0.05). Time-domain HRV indices-SDNN, SDANN, and pNN50-were significantly reduced in the CSF group compared to controls (p = 0.019, 0.037, and 0.008, respectively). Frequency-domain parameters showed no significant between-group differences. These findings suggest a predominance of sympathetic activity and diminished vagal modulation in CSF patients.

Conclusion: Reduced HRV in CSF patients indicates a significant autonomic imbalance, with increased sympathetic tone and reduced parasympathetic modulation. These alterations may contribute to the microvascular dysfunction underlying CSF and represent a potential therapeutic target.

Keywords: Autonomic nervous system, Coronary slow flow, Heart rate variability, Microvascular angina, Sympathetic dominance,

Received: July 3, 2025; Revised: July 3, 2025; Accepted: July 8, 2025; Prepublished online: June 2, 2012; Published: March 15, 2026  Show citation

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Tanriverdi O. Autonomic Nervous System Imbalance Reflected by Reduced Heart Rate Variability in Patients with Coronary Slow Flow. Cor Vasa. 2026;68(1):39-42.
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