LA staging tied to risk of new-onset AF in HCM

Mechanistic insights into how the left atrium (LA) adapts to progressive diastolic dysfunction in patients with hypertrophic cardiomyopathy (HCM) can be gleaned through a proposed physiological LA staging framework, which is associated with a graded risk of new-onset atrial fibrillation (AF) and potentially useful in creating AF surveillance strategies, suggests a study.

A total of 1,856 patients were screened, of whom 705 met the eligibility criteria (mean age 57.6 years, 30.1 percent female). Over a median follow-up of 7.5 years, 101 new-onset AF had occurred.

The staging system independently correlated with a significant, stepwise increase in the risk of new-onset AF (adjusted hazard ratio, 1.83 per increment, 95 percent confidence interval, 1.42‒2.37; p<0.001) and delivered incremental predictive value beyond established risk models (CHARGE-AF and HCM-AF).

These findings persisted in the 1-year landmark and competing-risk analyses, as well as in an external validation cohort involving 425 participants (mean age 59.7 years, 33.9 percent female).

Furthermore, 217 patients underwent serial echocardiography 4 to 6 years after baseline. Results showed a predominantly unidirectional evolution of the proposed LA framework, with many patients remaining stable (39.6 percent) or progressing to higher stages or AF (43.8 percent).

This multicentre retrospective study consisted consecutive HCM patients with normal left ventricular systolic function from January 2007 to February 2024 at two academic referral centres. Those with valvular heart disease or prior AF were excluded from the analysis.

The researchers categorized patients by combining the presence of elevated LA pressure (haemodynamic load) and LA contractile strain (intrinsic LA function): stage 1 (normal LA pressure and function), stage 2 (relative contractile augmentation for a given LA pressure), stage 3 (loss of relative contractile augmentation despite elevated LA pressure), stage 4 (elevated LA pressure with decreased LA contractile strain), and isolated LA contractile dysfunction.