Clinical Profile and Consequences of Atrial Fibrillation in Hypertrophic Cardiomyopathy

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Abstract

Background—

Atrial fibrillation (AF), the most common sustained arrhythmia in hypertrophic cardiomyopathy (HCM), is capable of producing symptoms that impact quality of life and is associated with risk for embolic stroke. However, the influence of AF on clinical course and outcome in HCM remains incompletely resolved.

Methods—

Records were accessed of 1558 consecutive patients followed at the Tufts Medical Center Hypertrophic Cardiomyopathy Institute for 4.8 ± 3.4 years, from 2004 to 2014.

Results—

Of the 1558 HCM patients, 304 (20%) had episodes of AF, of which 226 (74%) were confined to symptomatic paroxysmal AF (PAF; average 5 ± 5; range 1 to > 20), while 78 (26%) developed permanent AF, preceded by 7 ± 6 PAF episodes. At last evaluation, 277 patients (91%) are alive at 62 ± 13 years of age, including 89% in NYHA class I or II. There was no difference in outcome measures for AF patients and age and gender matched HCM patients without AF. Four percent of AF patients died of HCM-related causes (n=11) with annual mortality 0.7 %; mortality directly attributable to AF (thromboembolism without prophylactic anticoagulation) was 0.1 %/year (n=2 patients). Patients were treated with antiarrhythmic drugs (most commonly amiodarone [n=103] or sotalol [n=78]), and with AF catheter ablation (n=49) or Maze procedure at surgical myectomy (n=72). Freedom from AF recurrence at 1 year was 44% for ablation patients and 75% with Maze (p<0.001). Embolic events were less common with anticoagulation prophylaxis (4/233; 2%) than without (9/66; 14%) (p<0.001).

Conclusions—

Transient symptomatic episodes of AF, although relatively uncommon in HCM, are unpredictable in frequency and timing, amenable to effective contemporary treatments, and infrequently progress to permanent AF. AF is not a major contributor to heart failure morbidity, nor a cause of arrhythmic sudden death, and when treated is associated with low-disease-related mortality, no different than for patients without AF. AF is an uncommon primary cause of death in HCM virtually limited to embolic stroke, supporting a low threshold for initiating anticoagulation therapy.

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