Toshiki Setoguchi, Naoya Matsumoto, Yuro Matsunaga, Naoto Ohtsuka, Masaki Monden, Hidesato Fujito, Tsukasa Yagi, Michiaki Matsumoto, Yasuyuki Suzuki, Daisuke Fukamachi, 横山 勝章, Yasuo Okumura, Tsuyoshi Yamuchi
Background Right-sided chest precordial electrocardiogram (ECG) leads (V 3 R–V 5 R) are critical for diagnosing right ventricular (RV) infarction complicating acute inferior wall myocardial infarction. However, obtaining these leads in emergency settings can be time-consuming. This study compared measured and synthesized right-sided precordial ECGs to determine whether a synthesized ECG derived from a standard 12‑lead tracing can serve as a reliable alternative. Methods We retrospectively analyzed 38 patients (admitted between 2016 and 2024) with acute inferior wall myocardial infarction who underwent both measured and synthesized right-sided precordial ECGs. ST-segment deviation from the isoelectric line was quantified at the ST junction (STJ), at 40 ms (ST1), and 80 ms (ST2) thereafter for V 3 R–V 5 R. Agreement was evaluated using Pearson's correlation, Bland–Altman analysis, and receiver-operating-characteristic (ROC) curve analysis for the detection of RV infarction (ST elevation ≥0.1 mV in V 4 R). Results Pearson's r for measured versus synthesized ECGs was 0.90 for V 3 R, 0.84 for V 4 R, and 0.78 for V 5 R (all P < 0.001). Bland–Altman plots showed negligible bias (mean difference ≤ 0.02 mV) with narrow 95% limits of agreement (~ ± 0.12 mV). Diagnostic performance was equivalent between synthesized and measured V 4 R (ΔAUC = 0.0028; SE = 0.0551; 95% CI −0.105 to 0.111; z = 0.0505; P = 0.9598). Conclusions Synthesized right-sided precordial ECGs derived from a standard 12‑lead tracing closely reproduce measured leads in acute inferior wall myocardial infarction and may enable rapid identification of RV infarction without delaying reperfusion therapy.