This secondary analysis of the Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke trial examined whether corrected QT (QTc) interval prolongation predicts recurrent stroke in patients with recent cryptogenic stroke and atrial cardiopathy. The original trial, conducted in North America between 2018 and 2023, randomized patients to apixaban or aspirin for recurrent stroke prevention. For this analysis, patients with missing electrocardiographic data or prolonged QRS duration (≥120 ms) were excluded. The results of the study were published in the Heart.

Among 881 eligible patients, 139 (15.8%) had prolonged cohort-specific QTc. QT intervals were corrected using a cohort-specific formula and standard methods including Framingham, Hodges, Bazett, and Fridericia corrections. Over a mean follow-up of 1.8 years, 62 patients experienced recurrent stroke of any type (crude rate 7.0%; annualized rate 3.9% per year).

After multivariable adjustment, QTc prolongation was associated with a reduced risk of recurrent stroke (hazard ratio per standard deviation increase 0.72; 95% CI 0.54–0.95; and HR 0.16; 95% CI 0.04–0.64 for prolonged vs normal QTc). Findings were consistent across QT correction methods and remained unchanged after accounting for baseline ECG timing, incident atrial fibrillation, QRS duration, and competing risk of death.
In this selected population, QTc prolongation was associated with lower recurrent stroke risk.

These findings differ from associations reported for first stroke in general populations and may reflect unique characteristics of patients with cryptogenic stroke and atrial cardiopathy. If confirmed in broader populations, these findings suggest that electrocardiographic markers such as QTc may have distinct implications for risk stratification in first versus recurrent stroke.