Morphology of ventricular premature beats as an aid in the electrocardiographic diagnosis of myocardial infarction.

To determine whether morphologic analysis of ventricular premature beats (VPBs) can aid in the electrocardiographic diagnosis of myocardial infarction (MI), 12-lead electrocardiograms were evaluated in 760 consecutive patients who underwent cardiac catheterization, and 2-minute multiple-lead rhythm strips were evaluated in 515 of these patients. VPBs occurred in 58 patients; 21 had prior MI diagnosed by regional akinesia or dyskinesia on left ventricular cineangiography. Standard criteria were used to diagnose prior MI from the sinus beats of the electrocardiogram. Infarction was diagnosed from the morphology of a VPB when it had a QR or QRS pattern with Q wave greater than or equal to 0.04 second. Morphologic analysis of VPBs had a low sensitivity (29%) but high specificity (97%) and high predictive value (86%) for the diagnosis of MI. Sinus beats diagnosed MI with higher sensitivity (52%, and 69% if patients with left bundle branch block and left ventricular hypertrophy were excluded from analysis) than VPB morphologic analysis (p less than 0.05), but with similar specificity (97%) and predictive value (92%). Two patients with angiographic MI had no MI according to standard electrocardiographic criteria, but did have an MI manifest by VPB morphologic analysis. Despite low sensitivity, analysis of the morphology of VPBs may be useful for the diagnosis of MI when the morphology of sinus beats is not diagnostic. Therefore, VPB analysis is complementary to the standard electrocardiographic diagnosis of MI.