Hoshino T, Nagao T, Shiga T, Maruyama K, Toi S, Mizuno S, et al. Prolonged QTc Interval Predicts Poststroke Paroxysmal Atrial Fibrillation. Stroke. 2014
There has been significant research interest in the last few years focusing on cryptogenic stroke patients and the need for long term cardiac ambulatory telemetry to maximize the chance of detecting paroxysmal atrial fibrillation (PAF) in the cohort. CRYSTAL AF and EMBRACE trials were published in June this year and made a strong case for 30 day monitoring, especially in patients above age 55. For vascular neurologists, tools that help stratify a patient’s pretest probability assume special relevance as they may help tailor how long should a patient be monitored for PAF. In the cardiac literature, several EKG markers have been shown to be associated with future risk of PAF including P wave dispersion (difference between the longest and the shortest P-wave duration), P wave duration, and P-wave index (SD of P-wave duration across all leads).
In the current study, Hoshino et al assessed the predictive value of prolonged QT interval corrected for heart rate (QTc) in acute ischemic stroke patients with future detection of PAF. The retrospective analysis was carried out on the Tokyo Women’s Medical University stroke registry which includes 1038 consecutive acute ischemic stroke patients between April 2003 and Nov 2013. After exclusions, 744 patients were eligible for analysis. Mean age in the cohort was 67 years, and 9.3% patients had PAF detected post-stroke with median latency of 3 days. Age, absence of vascular etiology, congestive heart failure, left atrial dilation on TTE, and higher admission NIHSS score were associated with PAF. Longer QTc interval was an independent predictor of PAF, with OR 1.41 per 10ms increase in QTc. Despite important limitations of the study such as its retrospective nature and limited external validity in the US population (QTc has been shown to have ethnic differences), it replicates data from cardiac patients in the ischemic stroke population for the first time. Detecting PAF is extremely important in appropriate stroke patients as it leads to a change in management, and a potential for drastic risk reduction for future strokes. Biomarkers like QTc enable us to reliably predict or identify these patients, and thus help advance acute clinical stroke care.