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 (V-7 to V- 9) and right ventricular (V4R to V6R) leads to assess their accuracy c ompared with standard 12-lead electrocardiograms (ECGs) for the diagno sis of acute myocardial infarction (AMI). Patients aged >34 years with suspected AMI received posterior and right ventricular leads immediat ely after the initial 12-lead EGG. ST elevation of 0.1 mV in 2 leads w as blindly determined and inter-rater reliability estimated. AMI was d iagnosed by World Health Organization criteria. The diagnostic value o f nonstandard leads was determined when 12-lead ST elevation was absen t and present and multivariate stepwise regression analysis was also p erformed. Of 533 study patients, 64.7% (345 of 533) had AMI and 24.8% received thrombolytic therapy. Posterior and right ventricular leads i ncreased sensitivity for AMI by 8.4% (p = 0.03) but decreased specific ity by 7.0% (p = 0.06). The likelihood ratios of a positive test for 1 2, 12 + posterior, and 12 + right ventricular ECGs were 6.4, 5.6, and 4.5, respectively. Increased AMI rates (positive predictive values) we re 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 wit h this electrocardiographic gradient. Logistic regression analysis sho wed that 4 leads were independently predictive of AMI (p <0.001): lead s I, II, V-3, V5R; V-9 approached statistical significance (p = 0.055) . The standard ECG is not optimal for detecting ST-segment elevation i n AMI, but its accuracy is only modestly improved by the addition of p osterior and right ventricular leads. (C) 1997 by Excerpta Medico, Inc .