The Hidden Signal: P Wave Morphology and In-Hospital Mortality in Acute Pulmonary Embolism

<b>Background</b>: Electrocardiographic (ECG) abnormalities are common in acute pulmonary embolism (PE), but the prognostic significance of P wave morphology remains unclear. Early identification of high-risk patients is critical for guiding therapy and monitoring. <b>Methods</b>: We retrospectively analyzed 300 patients with confirmed PE. P wave morphology (normal, biphasic, notched, peaked) was evaluated for association with in-hospital mortality using chi-square and logistic regression, adjusted for age, sex, PESI score, and oxygen saturation. <b>Results</b>: Mortality differed significantly across P wave groups (χ² = 35.3, df = 3, <i>p</i> < 0.001). In univariate analysis, biphasic (OR 15.38, 95% CI 5.02-47.10, <i>p</i> < 0.001) and peaked (OR 7.21, 95% CI 2.35-22.10, <i>p</i> = 0.001) morphologies were strongly associated with mortality, whereas notched P waves were not (OR 1.44, 95% CI 0.16-12.87, <i>p</i> = 0.743). After adjustment, biphasic (OR 14.87, 95% CI 4.77-46.37, <i>p</i> < 0.001) and peaked (OR 6.58, 95% CI 2.11-20.53, <i>p</i> = 0.001) shapes remained independent predictors. Age, sex, PESI score, and oxygen saturation were not significant in multivariable analysis. <b>Conclusions</b>: Biphasic and peaked P wave morphologies on ECG are strong predictors of in-hospital mortality in patients with PE. Routine assessment of P wave shape may provide a simple tool for early risk stratification, warranting validation in prospective cohorts.