Biatrial arrhythmogenic substrate in patients with hypertrophic obstructive cardiomyopathy

Heart Rhythm. 2024 Jun;21(6):819-827. doi: 10.1016/j.hrthm.2024.01.022. Epub 2024 Jan 20.


Background: Atrial fibrillation (AF) in patients with hypertrophic obstructive cardiomyopathy (HOCM) may be caused by a primary atrial myopathy. Whether HOCM-related atrial myopathy affects mainly electrophysiological properties of the left atrium (LA) or also the right atrium (RA) has never been investigated.

Objective: The purpose of this study was to characterize atrial conduction and explore differences in the prevalence of conduction disorders, potential fractionation, and low-voltage areas (LVAs) between the RA and LA during sinus rhythm (SR) as indicators of potential arrhythmogenic areas.

Methods: Intraoperative epicardial mapping of both atria during SR was performed in 15 HOCM patients (age 50 ± 12 years). Conduction delay (CD) and conductin block (CB), unipolar potential characteristics (voltages, fractionation), and LVA were quantified.

Results: Conduction disorders and LVA were found scattered throughout both atria in all patients and did not differ between the RA and LA (CD: 2.9% [1.9%-3.6%] vs 2.6% [2.1%-6.4%], P = .541; CB: 1.7% [0.9%-3.1%] vs 1.5% [0.5%-2.8%], P = .600; LVA: 4.7% [1.6%-7.7%] vs 2.9% [2.1%-7.1%], P = .793). Compared to the RA, unipolar voltages of single potentials (SPs) and fractionated potentials (FPs) were higher in the LA (SP: P75 7.3 mV vs 10.9 mV; FP: P75 2.0 mV vs 3.7 mV). FP contained low-voltage components in only 18% of all LA sites compared to 36% of all RA sites.

Conclusion: In patients with HOCM, conduction disorders, LVA, and FP are equally present in both atria, supporting the hypothesis of a primary atrial myopathy. Conceptually, the presence of a biatrial substrate and high-voltage FP may contribute to failure of ablative therapy of atrial tachyarrhythmias in this population.

Keywords: Atrial fibrillation; Atrial myopathy; Hypertrophic obstructive cardiomyopathy; Mapping; Myectomy.

MeSH terms

  • Atrial Fibrillation* / diagnosis
  • Atrial Fibrillation* / physiopathology
  • Atrial Fibrillation* / surgery
  • Cardiomyopathy, Hypertrophic* / complications
  • Cardiomyopathy, Hypertrophic* / physiopathology
  • Electrocardiography
  • Epicardial Mapping / methods
  • Female
  • Heart Atria* / physiopathology
  • Heart Conduction System / physiopathology
  • Humans
  • Male
  • Middle Aged