Author + information
- Fernando M. Contreras-Valdes, MD,
- Alfred E. Buxton, MD,
- Mark E. Josephson, MD and
- Elad Anter, MD∗ ()
- ↵∗Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, 185 Pilgrim Road, Baker 4, Boston, Massachusetts 02215
Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HCM), present in 20% to 25% (1). Radiofrequency (RF) ablation is a safe and effective option for selected patients with symptomatic AF. However, its efficacy in patients with HCM has been less studied. AF in this group may have different mechanisms and thus, catheter ablation may have a different effect. We compared the long-term clinical efficacy of AF ablation between patients with and those without HCM and aimed to identify predictors of recurrence in patients with HCM.
We analyzed 40 patients with primary HCM (age, 54.3 ± 7.3 years; 70% men) and symptomatic AF (67.5% persistent) undergoing index ablation between 2006 and 2012. Their outcomes were compared with those of 64 patients (age, 56.2 ± 5.8 years; 70% men) with similar AF characteristics (70.3% persistent) without HCM over the same period. The diagnosis of HCM and classification of AF were made according to current guidelines. Patients with long-standing persistent AF were excluded. Our standard approach to AF ablation has been described (2). Acute successful ablation, defined as isolation of all pulmonary veins (PVs) and ablation of sustained organized atrial tachyarrhythmias (OAT), was achieved in all patients. Repeat procedures were performed as clinically indicated in those with recurrence. The median follow-up was 54 months (HCM, 22 to 67 vs. 35 to 67 comparison; p = 0.66). The HCM group had a mean left ventricular (LV) wall thickness of 17.5 ± 2.8 mm. LV outflow obstruction at rest was present in 37.5% of patients with HCM (mean gradient, 37 ± 12.5 mm Hg).
The 1-year arrhythmia-free survival off anti-arrhythmic drugs (AADs) was lower in the HCM group (42.5% vs. 70.3%; p = 0.005), and the ablation efficacy declined until the end of follow-up (35% vs. 67.2%; p = 0.001). The recurrent arrhythmia was AF in all (n = 26) with HCM (vs. 95% [n = 20] in non-affected), along with coexisting OAT in 34.5% (n = 9) (vs. 14.5% [n = 3] in non-affected). Twelve patients in the HCM group (30%) underwent a single repeat ablation and 1 patient underwent 2 repeat ablations (mean 1.32 ± 0.5). In the non-affected group, 12 patients (18.8%) underwent a single redo; none had a third procedure (mean, 1.18 ± 0.4; p = 0.7). Most patients had chronic PV reconnection (HCM, 61.5% vs. 91.6% in non-affected cohort; p = 0.0004), whereas the remaining patients had OATs that were mapped and ablated. Repeat procedures resulted in improved arrhythmia freedom; however, the effect on patients with HCM was lower (1 year: 45% vs. 75%; p = 0.001; end of follow-up: 47.5% vs. 73.4%; p = 0.005) (Figure 1A). Similarly, arrhythmia control, defined as maintenance of sinus rhythm with or without AADs, was also lower (60% vs. 82.8%; p = 0.01) (Figure 1B). Patients with HCM were more likely to require chronic AADs (45% vs. 18.8%; p = 0.007), predominantly amiodarone (77.8% vs. 16.6%; p = 0.005).
Patients with HCM who had arrhythmia recurrence were more likely to have LV outflow obstruction (57.7% vs. 0%; p < 0.0001), with only 20.8% maintaining sinus rhythm at the end of follow-up. LV outflow obstruction was an independent predictor of arrhythmia recurrence (hazard ratio: 4.3; 1.6 to 11.4; p = 0.0007). Baseline left atrial pressure ≥12 mm Hg (hazard ratio: 3.1; 1.4 to 7.1; p = 0.005) and dilated left atrium (1.06; 1.003 to 1.11 per mm; p = 0.04) were associated with recurrence only in univariate analysis. Procedure-related complications were rare. However, median hospitalization was longer in the HCM group (2 [1 to 6] vs. 1 [1 to 3] days; p < 0.0001), with a higher readmission rate at 30 days (25% vs. 1.6%; p = 0.0003) as the result of heart failure with congestive symptoms.
Our study is the first comparing long-term arrhythmia control among patients with HCM and a non-affected cohort. We found that the efficacy of AF ablation is significantly lower compared with non-affected patients, irrespective of the number of procedures or use of AADs (3). In fact, these are frequently required. Potential explanations include anatomic variations in atrial thickness in patients with HCM as well as different AF substrate and non-PV triggers. In this study, re-isolation of all chronically reconnected PVs did not improve arrhythmia control in patients with HCM to the same extent as that in non-affected subjects. Our results indicate that AF ablation is safe in the HCM population, although it can be associated with significant post-procedural volume retention and pulmonary edema requiring treatment. When present, LV outflow obstruction is a strong predictor of recurrence.
Please note: Dr. Buxton has received research grants from Biosense Webster and Medtronic. Dr. Josephson has received research grants and speaking honoraria from Medtronic. Dr. Anter has received research grants and speaking honoraria from Biosense Webster and Boston Scientific. Dr. Contreras-Valdes has reported that he has no relationships relevant to the contents of this paper to disclose.
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