What does this research mean for the field?

In patients with hypertrophic cardiomyopathy, paroxysmal atrial fibrillation is associated with greater left atrial structural remodeling, higher left atrial fibrosis, and global myopathy, indicating a more severe cardiac phenotype. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

December 26, 2018JACC. Clinical electrophysiologyOpen Access

Hypertrophic Cardiomyopathy Patients With Paroxysmal Atrial Fibrillation Have a High Burden of Left Atrial Fibrosis by Cardiac Magnetic Resonance Imaging

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Why the study?

It is unresolved whether AF is a marker or a mediator of adverse outcomes in HCM, prompting the hypothesis that PAF reflects a more severe cardiac phenotype.

Is paroxysmal atrial fibrillation associated with greater left atrial fibrosis and structural remodeling in patients with hypertrophic cardiomyopathy?

Structured PICO

Is paroxysmal atrial fibrillation associated with greater left atrial fibrosis and structural remodeling in patients with hypertrophic cardiomyopathy?

Population

45 patients with hypertrophic cardiomyopathy (HCM) who underwent cardiovascular magnetic resonance (CMR) imaging in sinus rhythm

Intervention

History of paroxysmal atrial fibrillation (PAF) (n=18)

Comparator

No history of atrial fibrillation (n=27)

Outcome

Left atrial late gadolinium enhancement (LA-LGE) as an indicator of fibrosis, LA volume, LA ejection fraction, and global peak longitudinal LA strain (PLAS)surrogate

In patients with hypertrophic cardiomyopathy, paroxysmal atrial fibrillation is associated with a greater degree of structural left atrial remodeling and global myopathy, indicating a more severe phenotype.

Implication

PAF marks more severe LA myopathy in HCM; hypothesis-generating for targeted interventions pending prospective data.

Abstract

OBJECTIVES: This study hypothesized that paroxysmal atrial fibrillation (PAF) reflects the presence of a more severe cardiac hypertrophic cardiomyopathy (HCM) phenotype. BACKGROUND: HCM is characterized by myocyte hypertrophy, fibrosis, and a high prevalence of PAF. It is currently unresolved whether atrial fibrillation (AF) is a marker or a mediator of adverse outcomes in HCM. METHODS: This study retrospectively examined 45 HCM patients who underwent cardiovascular magnetic resonance (CMR) imaging in sinus rhythm. The function of all 4 cardiac chambers was assessed, as well as late gadolinium enhancement (LGE) in the left atrium (LA) and left ventricle (LV), as indicators of fibrosis. A fat-saturated, 3-dimensional inversion recovery-prepared, fast-spoiled, gradient-recalled echo sequence, and the image intensity ratio method were used to measure LA-LGE; LGE in the LV was quantified using a semi-automated threshold technique. RESULTS: HCM patients (n = 45) were divided into 2 groups (PAF, no AF) based on history of PAF. All HCM patients had LGE in the LA posterior wall. The PAF group (n = 18) had higher LA volume, a lower LA ejection fraction, a lower global peak longitudinal LA strain (PLAS), and a higher amount of LA-LGE compared with the no AF group (n = 27). A modest inverse association was noted between the LA ejection fraction, PLAS, and LA-LGE; a positive association was present between LV-LGE and LA-LGE. The PAF group had lower ejection fractions in the LV, right atrium, and right ventricle compared with those in the no AF group. CONCLUSIONS: PAF is associated with a greater degree of structural LA remodeling and global myopathy, which suggests a more severe cardiac HCM phenotype.