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TOPLINE
Researchers developed a novel left atrium (LA) staging system that helped predict which patients with hypertrophic cardiomyopathy (HCM) were at a higher risk of developing new-onset atrial fibrillation (AF). The risk rose progressively with each increase in stage. Adding the system to established risk models further improved prediction.
METHODOLOGY
- Researchers conducted a retrospective cohort study to develop a novel LA staging system and evaluate its ability to predict new-onset AF in patients with HCM.
- The primary cohort included 705 patients (mean age, 57.6 years; 30.1% women) with HCM but normal left ventricular ejection fraction (LVEF) from two academic referral centers between January 2007 and February 2024.
- Patients were classified using two factors — elevated LA pressure and LA contractile strain — into four categories: stage 1 (normal LA pressure and contractile function), stage 2 (compensatory augmentation for a given LA pressure), stage 3 (loss of the compensatory response despite elevated LA pressure), stage 4 (elevated pressure and reduced contractile function). An additional category included patients with isolated LA contractile dysfunction.
- External validation was performed in an independent cohort of 425 patients with HCM (mean age, 59.7 years) from a geographically distinct tertiary referral center.
- New-onset AF served as the study's main endpoint, confirmed either by standard ECG or with continuous ECG monitoring showing an episode lasting at least 30 seconds. The median follow-up duration was 7.5 years in the primary cohort and 8.2 years in the external validation cohort.
TAKEAWAY
- Over the course of follow-up, new-onset AF occurred in 14.3% of patients. Cumulative event rates were estimated at 8.1% (95% CI, 5.8%-10.3%) at 5 years and 20.0% (95% CI, 16.1%-23.8%) at 10 years.
- The risk for new-onset AF increased progressively with advancing LA stage, with each stage increase associated with an 83% higher risk (adjusted hazard ratio [aHR], 1.83; P < .001). Compared with patients in stage 1, patients in stage 4 had more than seven times the risk of developing AF (aHR, 7.44; P < .001).
- When added to established risk models, the LA staging system improved 10-year prediction of new-onset AF, with the C-statistic increasing from 0.702 to 0.748 when the addition was to the CHARGE-AF model and from 0.765 to 0.791 when the addition was to the HCM-AF model (P < .05).
- The LA staging system performed consistently in the external validation cohort, with each stage increase associated with a significantly higher risk for new-onset AF (aHR, 1.82; P < .001); the system continued to add meaningful predictive value beyond existing risk models.
IN PRACTICE
"We propose a novel LA staging system in HCM that characterizes the adaptation of the LA against LA pressure and carries prognostic significance regarding NOAF [new-onset atrial fibrillation]," the researchers wrote.
"One of the notable findings is a very low incidence of NOAF in stage 1. This may justify de-escalation of surveillance for these patients, while simultaneously allowing resources to be allocated to higher risk patients," they added.
SOURCE
The study was led by Jaehyun Lim, MD, PhD, Seoul National University College of Medicine and Seoul National University Hospital in Seoul, South Korea. It was published online on September 9 in the Journal of the American College of Cardiology.
LIMITATIONS
The findings come from a cohort composed largely of Asian patients. The study also included only patients with normal LVEF. Follow-up ended for any patient who later underwent septal reduction therapy or started a cardiac myosin inhibitor, since these treatments can alter how the left atrium functions.
DISCLOSURES
The study was supported by a grant from Chong Kun Dang Pharm and partly by the Cardiomyopathy Education and Research Center in Seoul. One author declared being a consultant for a pharmaceutical company in Korea and reported receiving research grants from the company and the study funding source. The remaining authors reported having no relevant conflicts of interest.
This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.
