Interrelationship of variable coupling, multiformity and repetitive forms: implications for classification of ventricular arrhythmias.

One hundred 24-hour ambulatory electrocardiograms were prospectively examined to determine the relationship of variable coupling and multiformity of single premature ventricular complexes to repetitive forms. Premature ventricular complexes were present in 86 patients and were categorized by a three-tier decision-making tree using (1) multiformity confirmed in two channels, (2) variable coupling of greater than 80 msec of premature ventricular complexes of similar QRS morphologies, and (3) repetitive forms of greater than or equal to 2 premature ventricular complexes. Variable coupling was present in 51 patients, among whom 35 (69%) had repetitive forms; multiformity was present in 46 patients, among whom 37 (80%) had repetitive forms; repetitive forms were present in 41 patients, among whom only one patient (2%) did not demonstrate multiformity or variable coupling. Variable coupling, multiformity, or either were significantly associated with the occurrence of repetitive forms (chi square = 34, 15, 29, respectively, each p less than 0.005). There was a bimodal distribution between patients with uniform, fixed coupled premature ventricular complexes who had rare repetitive forms (1 of 26) and patients with multiformity and variable coupling of premature ventricular complexes who had significantly more repetitive forms (30 of 37; p less than 0.001). The frequency distribution of repetitive form length suggested a natural break point between five and six consecutive complexes.(ABSTRACT TRUNCATED AT 250 WORDS)