Poor reliability of P-wave terminal force V1 in ischemic stroke.

INTRODUCTION

Several ECG markers are postulated to represent underlying atrial remodelling and have been associated with ischemic stroke. P-wave terminal force in lead V1 (PTFV1) is one such marker. We examined the factors that contribute to the reliability of PTFV1 and its association with ischemic stroke.

MATERIAL AND

METHODS

Four hundred and thirty-five patients that presented with an ischemic stroke or transient ischemic attack (TIA) were identified through a prospectively maintained multi-site institutional stroke database. Control group consisted of age matched patients without prior history of an ischemic stroke or TIA. All patients underwent a 12-lead ECG and 24-hour Holter monitoring during the study period to exclude atrial fibrillation.

RESULTS

Morphology consistent with PTFV1 occurred commonly in both the stroke/TIA and control groups. There was no significant difference in the median PTFV1 value between the stroke 3.96 mV ms [Interquartile range (IQR) 2.78-5.58] and control 4.23 mV ms [IQR 2.91-5.57] groups. Measurements of PTFV1 demonstrated excellent intra-observer reliability on assessment of the same P-wave (Intra class correlation (ICC) 0.91, p < 0.001) with narrow limits of agreement 2.21 to -2.95 mV ms. A change in the P wave assessed led to a significant reduction in reliability (ICC 0.79, p < 0.001). Inter-observer, inter P-wave assessment demonstrated further reduction in reliability (ICC 0.68, p < 0.002) with wide limits of agreement 6.17 to -5.78 mV ms, indicating significant under and overestimation of PTFV1.

CONCLUSION

The utility of PTFV1 as a clinical marker for ischemic stroke is limited by the reduction in reliability associated with inter-observer and inter P-wave measurements.