Clinical significance of R‐wave amplitude in lead V₁ and inferobasal myocardial infarction in patients with inferior wall myocardial infarction

Abstract

ObjectiveTo assess electrocardiogram (ECG) for risk stratification in inferior ST‐elevation myocardial infarction (STEMI) patients within 24 h.MethodsThree hundred thirty‐four patients were divided into four ECG‐based groups: Group A: R V1 <0.3 mV with ST‐segment elevation (ST↑) V7–V9, Group B: R V1 <0.3 mV without ST↑ V7–V9, Group C: R V1 ≥0.3 mV with ST↑ V7–V9, and Group D: R V1 ≥0.3 mV without ST↑ V7–V9.ResultsGroup A demonstrated the longest QRS duration, followed by Groups B, C, and D. ECG signs for right ventricle (RV) infarction were more common in Groups A and B (p < .01). ST elevation in V6, indicative of left ventricle (LV) lateral injury, was more higher in Group C than in Group A, while the ∑ST↑ V3R + V4R + V5R, representing RV infarction, showed the opposite trend (p < .05). The estimated LV infarct size from ECG was similar between Groups A and C, yet Group A had higher creatine kinase MB isoform (CK‐MB; p < .05). Cardiac troponin I (cTNI) was higher in Groups A and C than in B and D (p < .05 and p = .16, respectively). NT‐proBNP decreased across groups (p = .20), with the highest left ventricular ejection fraction (LVEF) observed in Group D (p < .05). Group A notably demonstrated more cardiac dysfunction within 4 h post‐onset.ConclusionsFor inferior STEMI patients, concurrent R V1 <0.3 mV with ST↑ V7–V9 suggests prolonged ventricular activation and notable myocardial damage. RV infarction's dominance over LV lateral injury might explain these observations.