Patients with transposition of the great arteries (TGA) corrected by an atrial switch operation have an increased risk for major clinical events throughout adulthood, with the risk for first heart failure (HF) increasing most rapidly to a 5-year risk of 23% at approximately 50 years of age, according to the results of a study published in the Journal of the American Heart Association.

Investigators sought to assess the risk for major clinical events — HF, ventricular arrhythmia, and death — in adults after atrial switch for TGA up to the sixth decade of life and provide a novel risk score for event-free survival.

The researchers followed 167 patients (median age, 28; 62% men) who had TGA corrected by an atrial switch operation (61% Mustard procedure) for a median of 13 years (interquartile range [IQR], 9-16 years). During the follow-up period, 16 (10%) patients died, 33 (20%) had HF events (defined as HF hospitalizations, heart transplantation, ventricular assist device implantation, or HF-related death), and 15 (9%) had symptomatic ventricular arrhythmias.


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The 5-year risk for mortality, first HF event, and first ventricular arrhythmia increased from 1% each at age 25 to 30 years to 6% (95% CI, 4%-9%), 23% (95% CI, 17%-28%), and 5% (95% CI, 2%-8%), respectively, at age 50 to 55 years.

The study authors then examined predictors of event-free survival to construct a prediction model. The model combined age >30 years, prior ventricular arrhythmia, age >1 year at repair, moderate or greater right ventricular dysfunction, severe tricuspid regurgitation, and mild or greater left ventricular dysfunction and discriminated well between patients with a low (<5%), intermediate (5%–20%), and high (>20%) 5-year risk (optimism-corrected C-statistic, 0.86 [95% CI, 0.82-0.90]).

The event-free survival rates in low-risk patients at 5 and 10 years were 100% and 97%, respectively. In comparison, these rates were 31% and 8%, respectively, in high-risk patients.

“The clinical course of patients undergoing atrial switch increasingly consists of major clinical events, especially HF,” the investigators wrote. “A novel risk score stratifying patients as low, intermediate, and high risk for event-free survival provides information on absolute individual risks, which may support decisions for pharmacological and interventional management.”

Study limitations include the observational design and follow-up of a selected group of patients treated in tertiary medical centers. In addition, the sample size was limited to 167 patients, with only 41 reaching the primary endpoint.

“The risk score may assist in counseling patients about their absolute risk, help determine follow-up intensity, and support management decisions on prevention and treatment of the prevailing complications,” the study authors commented.

Reference

Woudstra OI, Zandstra TE, Vogel RF, et al. Clinical course long after atrial switch: a novel risk score for major clinical events. J Am Heart Assoc. 2021;10(5):e018565.