Electrocardiographic P-wave peak time predicts significant ischemia in INOCA patients: A pilot study.

Background: Ischemia with non-obstructive coronary arteries (INOCA) represents a diagnostic and therapeutic challenge, often related to coronary microvascular dysfunction (CMD). Identifying non-invasive electrocardiographic markers that predict ischemia in this population remains a clinical priority. P-wave peak time (PWPT), reflecting atrial conduction delay, has been linked to ischemic pathophysiology.

Methods: This retrospective, observational study included 444 patients who underwent coronary angiography with normal epicardial arteries followed by SPECT myocardial perfusion imaging (MPI) due to persistent anginal symptoms. Patients were classified into three groups based on the percentage of reversible left ventricular ischemia: <5 %, 5-10 %, and > 10 %. P-wave indices-including PWPT in leads DII and V1-were measured digitally by two independent observers. Multivariate logistic regression identified independent predictors of >10 % ischemia. ROC analysis assessed the discriminative power of PWPT.

Results: PWPT-DII and PWPT-V1 were significantly prolonged in patients with >10 % ischemia (63 ± 8 ms and 58 ± 9 ms, respectively) compared to patients with <5 % ischemia (55 ± 7 ms and 50 ± 8 ms; both p < 0.001). PWPT-DII yielded an AUC of 0.82 (95 % CI 0.77-0.86), outperforming PWPT-V1 (AUC 0.76). In multivariate models, PWPT-DII (OR 1.15, 95 % CI 1.08-1.23), PWPT-V1 (OR 1.10, 95 % CI 1.03-1.17), age, diabetes mellitus, and E/e' ratio emerged as independent predictors of significant ischemia.

Conclusions: Prolonged PWPT, particularly in lead DII, was observed to be independently associated with myocardial ischemia in INOCA. Incorporating PWPT into standard ECG interpretation may aid in risk stratification and early identification of CMD in patients with normal coronary angiograms but ongoing ischemic symptoms.