ST segment elevation and the prediction of hospital life-threatening complications: the role of right ventricular and posterior leads.

UNLABELLED: Accurate prognosis in suspected acute myocardial infarction (AMI) is essential for appropriate use of thrombolytic therapy and primary angioplasty. However, previous models may be limited because the 12-lead electrocardiogram (ECG) does not examine the right ventricular (RV) and posterior myocardium. We evaluated ST segment elevation (STSE) in posterior (V7-V9) and RV (V4R-V6R) leads to determine their predictive value for hospital life-threatening complications (HLTCs). METHOD AND RESULTS: This prospective trial of seven Midwestern hospital emergency departments (EDs) had inclusion criteria of age 35 years, chest pain suggestive of ischemia, and coronary care unit (CCU) admission. ECG leads were test positive if STSE was > 0.1 mV. Patients were positive for HLTCs if ED or inpatient hospital course included: ventricular fibrillation or tachycardia, second- or third-degree block, shock, arrest, or death. Univariate and multivariate analyses were performed to test each lead's association with HLTCs. Of 533 patients, 64.7% (345/533) had AMI and 15.8% (85/533) had HLTCs. The sensitivity of 18 leads for HLTCS was increased by 5.8%, but specificity decreased by 8.2%. ECG subgroups by STSE were associated with the following HLTC rates: inferior/+RV (32.4%); anterior (29.5%), lateral (23.1%), inferior RV (17.9%), and posterior (16.2%). V1 (odds = 3.2) and V6R (odds = 3.1) were statistically significant independent predictors. CONCLUSION: Posterior and RV leads did not increase the ECG's overall prognostic value, but in the presence of inferior STSE, were associated with low and high complication rates, respectively. Right and left precordial leads were the best predictors of HTLCs.

Value of posterior and right ventricular leads in comparison to the standard 12-lead electrocardiogram in evaluation of ST-segment elevation in suspected acute myocardial infarction.

In this multicenter prospective trial, we studied posterior (V7 to V9) and right ventricular (V4R to V6R) leads to assess their accuracy compared with standard 12-lead electrocardiograms (ECGs) for the diagnosis of acute myocardial infarction (AMI). Patients aged >34 years with suspected AMI received posterior and right ventricular leads immediately after the initial 12-lead ECG. ST elevation of 0.1 mV in 2 leads was blindly determined and inter-rater reliability estimated. AMI was diagnosed by World Health Organization criteria. The diagnostic value of nonstandard leads was determined when 12-lead ST elevation was absent and present and multivariate stepwise regression analysis was also performed. Of 533 study patients, 64.7% (345 of 533) had AMI and 24.8% received thrombolytic therapy. Posterior and right ventricular leads increased sensitivity for AMI by 8.4% (p = 0.03) but decreased specificity by 7.0% (p = 0.06). The likelihood ratios of a positive test for 12, 12 + posterior, and 12 + right ventricular ECGs were 6.4, 5.6, and 4.5, respectively. Increased AMI rates (positive predictive values) were found when ST elevation was present on 6 nonstandard leads (69.1%), on 12 leads only (88.4%), and on both 6 and 12 leads (96.8%; p <0.001). Treatment rates with thrombolytic therapy increased in parallel with this electrocardiographic gradient. Logistic regression analysis showed that 4 leads were independently predictive of AMI (p <0.001): leads I, II, V3, V5R; V9 approached statistical significance (p = 0.055). The standard ECG is not optimal for detecting ST-segment elevation in AMI, but its accuracy is only modestly improved by the addition of posterior and right ventricular leads.