Beyond arrhythmias in the ECG: Is there any correlation between QT interval and stroke subtype and severity?

Background: The QT interval in ECG is susceptible to autonomic fluctuations, a known occurrence in acute ischemic stroke (AIS). Previous research has highlighted QT interval changes between ischemic and haemorrhagic strokes. However, there is scarce literature on the differential effect of AIS subtypes on QT interval. Our objective was to determine the incidence of QT interval abnormalities in AIS patients and its association with stroke severity and subtype.

Methods: In our single-centre prospective-observational study, 100 patients with AIS were included. Clinical characteristics (stroke severity by NIHSS and disability by mRS), stroke subtype (TOAST-classification), imaging findings, and QTc (corrected QT) interval from ECG, upon admission, after 48 h and at 3-months were analyzed.

Results: At admission, 59 % patients had prolonged QTc interval, which decreased to 40 % after 48 h and 15 % at 3 months. Among those with QTc prolongation at admission, 52 % patients had large artery atherosclerosis (p-value 0.010). Significant QTc prolongation was observed in patients with moderate (55.5 %) and severe stroke (95.5 %) as well as with severe disability at admission (mRS 3 to 6; p-value < 0.001). There was also a significant association between prolonged QTc at admission and severe stroke deficits at discharge and at 3-month follow-up (p-value < 0.05). In multivariate analysis, only functional disability at admission remained significantly associated with prolonged QTc (odds ratio 4.303,95 % confidence interval 1.356-13.655). However, persistently prolonged QTc after 48 h was associated with worse NIHSS and mRS scores at discharge and 3 months (p-value < 0.05), independent of stroke severity and disability at admission. Interestingly, in patients whose QTc normalised at 48 h, 80 % had improved mRS scores at discharge (p-value < 0.001).

Conclusion: QTc-prolongation is common after AIS. Persistently prolonged QTc at 48 h was associated with poorer outcomes upon discharge and at 3-months. The difference in incidence of QTc prolongation may reflect a variable autonomic dysregulation, possibly influenced by the brain-heart axis, and differing stroke subtypes and severity.