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Biatrial arrhythmogenic substrate in patients with hypertrophic obstructive cardiomyopathy
Nawin L Ramdat Misier1, Jorik H Amesz1, Yannick J H J Taverne2
1Department of Cardiology, Erasmus Medical Center, Rotterdam, The Netherlands.
Insights
In patients with hypertrophic obstructive cardiomyopathy, conduction disorders and low-voltage areas are equally present in both atria, suggesting a primary atrial myopathy. This biatrial substrate may impact atrial tachyarrhythmia treatment outcomes.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Imaging
Background:
- Atrial fibrillation (AF) in hypertrophic obstructive cardiomyopathy (HOCM) may stem from primary atrial myopathy.
- The impact of HOCM-related atrial myopathy on the electrophysiology of the right atrium (RA) and left atrium (LA) remains unexplored.
Purpose of the Study:
- To characterize atrial conduction in HOCM patients.
- To compare the prevalence of conduction disorders, potential fractionation, and low-voltage areas (LVAs) between the RA and LA during sinus rhythm (SR).
Main Methods:
- Intraoperative epicardial mapping of both atria in 15 HOCM patients during SR.
- Quantification of conduction delay (CD), conduction block (CB), unipolar potential characteristics (voltages, fractionation), and LVAs.
Main Results:
- Conduction disorders and LVAs were found in both atria, with no significant difference between RA and LA (CD: P=.541, CB: P=.600, LVA: P=.793).
- Unipolar voltages of single potentials (SPs) and fractionated potentials (FPs) were higher in the LA compared to the RA.
- Low-voltage components within FPs were less frequent in the LA (18%) than in the RA (36%).
Conclusions:
- Conduction disorders, LVAs, and FPs are equally prevalent in both atria of HOCM patients, supporting a primary atrial myopathy hypothesis.
- The presence of a biatrial substrate and high-voltage FPs may influence the success of ablative therapy for atrial tachyarrhythmias in this population.
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.
