Key result
Absent V4R ST elevation in proximal RCA MI is linked to ~6.5-fold higher dominant RCA rates.
Why the study?
Although ST-segment elevation of >= 1.0 mm in lead V4R is a reliable marker of right ventricular involvement in inferior acute myocardial infarction, patients lacking ST-segment elevation in lead V4R despite right ventricular involvement had received little attention.
Observational (n=62)
Answers are grounded in this paper and cite their sources.
Shows that absent lead V4R ST elevation during inferior infarction reflects concomitant posterior damage, indicating right ventricular injury may be underestimated.
BACKGROUND: ST-segment elevation of > or = 1.0 mm in lead V4R has been shown to be a reliable marker of right ventricular involvement (RVI), a strong predictor of a poor outcome in patients with inferior acute myocardial infarction (IMI). However, patients with no ST-segment elevation in lead V4R despite the presence of RVI have received little attention. HYPOTHESIS: The study was undertaken to study the clinical features of patients with no ST-segment elevation in lead V4R despite the presence of RVI, which means false negative, as such patients have received little attention in the past. METHODS: We studied 62 patients with a first IMI, who had total occlusion of the right coronary artery (RCA) proximal to the first right ventricular branch and successful reperfusion within 6 h from symptom onset, to examine the implications of the absence of ST-segment elevation in lead V4R despite the presence of RVI. RESULTS: A standard 12-lead electrocardiogram (ECG) and right precordial ECG (lead V4R) were recorded on admission, and three posterior chest ECGs (leads V7 to V9) were additionally recorded in 34 patients. Patients were classified according to the absence (Group 1, n = 18) or presence (Group 2, n = 44) of ST-segment elevation of > or = 1.0 mm in lead V4R on admission. Patients in Group 1 had a greater ST-segment elevation in leads V7 to V9 (2.9+/-2.4 vs. 1.4+/-3.0 mm. p < 0.05), a higher frequency of a dominant RCA (defined as the distribution score > or = 0.7) (72 vs. 11%, p < 0.001), and a higher peak creatine kinase level (3760+/-1548 vs. 2809+/-1824 mU/ml, p < 0.05) than those in Group 2. CONCLUSIONS: In patients with IMI caused by the occlusion of the RCA proximal to the first right ventricular branch, no ST-segment elevation in lead V4R can occur because of concomitant posterior involvement. In such patients, the incidence of RVI may be underestimated on the basis of ST-segment elevation in lead V4R.
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Kosuge et al. (2001) conducted an observational in Inferior acute myocardial infarction with right ventricular involvement (n=62). Absence of ST-segment elevation >=1.0 mm in lead V4R on admission vs. Presence of ST-segment elevation >=1.0 mm in lead V4R on admission was evaluated on Frequency of a dominant right coronary artery (distribution score >=0.7) (p=<0.001). Absence of V4R ST elevation in proximal RCA inferior MI was associated with higher dominant RCA rates and greater V7-V9 ST elevation.
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