Value of premature ventricular contraction morphology in the detection of myocardial infarction.

A ventricular premature contraction (VCP) with a QR pattern has been associated with antecedent myocardial infarction. In order to determine the validity of this sign, we compared the presence of localized abnormal wall motion during left ventricular angiography with the morphology of VPC's induced in each patient by catheter stimulation of the left ventricular endocardium. The morphology of V1 was compared with anterior wall infarction, and of AVF with inferior wall infarction, and the specificity, sensitivity and predictive value of the QR VPC evaluated. A QR pattern VPC in V1 with a Q greater than or equal to 0.04 sec and a Q/R ratio = 0.20 had a specificity of 0.93, a sensitivity of 0.24 and a predictive value of 0.72 in the detection of anterior myocardial infarction. The detection rate was considerably increased with a Q/R ratio of greater than or equal to 0.1 and specificity remained high at 0.87. Detection of inferior infarction by use of AVF was less certain, and is probably of limited value.