Ventricular tachycardia in myocardial infarction: Relation to heart rate and premature ventricular contractions

Analysis of monitored electrocardiograms, recorded in 77 patientsduring the first 48 hours following the onset of myocardialinfarction, revealed 492 episodes of ventricular tachycardiawith rates of 90–220 min^–1. Characteristics of theventricular tachycardia episodes were correlated with heartrate and with the rate and complexity of ventricular arrhythmiasin the 10-min period preceding ventricular tachycardia. Ventriculartachycardia with rates of 140–180 min^–1 and witha QS configuration was the most frequent event. The first ectopiccomplex of VT was R-on-Tin only 17.2%. Sinus tachycardia wasassociated with significantly fewer episodes of VT with ratesof 110–140min^–1 than when the sinus rate was normal.However episodes of ventricular tachycardia with rates of 181to 220 beats min^–1 were more frequent during sinus tachycardia.Analysis of the frequency of premature ventricular contractionsin the 10-min period immediately preceding ventricular tachycardiarevealed no premature ventricular contractions in 24.4% of cases.Multiple premature ventricular contractions with a frequencyof >5 min^-1 were observed in 8.4% of cases, multifocal in30.3%, couplets in 24% and early PVCs in 12.2%. In the minutebefore ventricular tachycardia, only 40.2% of cases displayedpremature ventricular contractions. In that minute, complexpremature ventricular contractions were distributed as follows:multifocal in 10%, couplets in 8.7% and early PVCs in 2.6% ofcases. Out of the total of 492 runs of ventricular tachycardia,5 cases (1%) resulted in ventricular fibrillation. The frequencyand complexity of premature ventricular contractions as wellas the characteristics of ventricular tachycardia were foundto be of little predictive value for the immediate developmentof ventricular fibrillation in patients with acute myocardialinfarction.