Procainamide-induced percent changes in QRS duration at shorter paced cycle lengths significantly correlated with percent changes in ventricular tachycardia cycle length (r = 0.84, p<0.001).
Observational (n=18)
Does procainamide alter paced QRS duration in a way that correlates with changes in VT cycle length in patients with inducible VT?
The percent change in QRS duration at shorter paced cycle lengths after procainamide administration strongly correlates with the percent change in VT cycle length.
Effect estimate: r = 0.84
p-value: p=<0.001
To determine if paced cycle length-dependent changes in the QRS duration correlate with the change in ventricular tachycardia (VT) cycle length after procainamide, we measured the QRS duration during sinus rhythm and during right ventricular pacing before and after procainamide (mean concentration, 9.9 micrograms/ml) in 18 patients with morphologically identical VT induced at both study periods. Pacing was performed at 600 msec or the longest cycle length that allowed for uninterrupted capture and at a cycle length that was within 50 msec of the VT cycle length observed during the control study (mean, 313 +/- 51 msec). After procainamide, the VT cycle length increased from 285 +/- 62 to 368 +/- 70 msec (percent change, 30 +/- 13%). The QRS duration during sinus rhythm increased from 125 +/- 25 to 145 +/- 29 msec (percent change, 16%). The QRS duration at both paced cycle lengths was the same in the baseline state (191 +/- 26 msec). However, the change in QRS duration after procainamide at the shorter paced cycle length compared to a 39 +/- 13 msec (18%) increase at the longer paced cycle, p less than 0.001. There was a significant correlation between the percent change in QRS duration at the shorter paced cycle length and the percent change in VT cycle length (r = 0.84, p less than 0.001) with the relation expressed by the regression equation: percent change in VT cycle length = -2.8 + 1.16 x percent change in QRS duration.(ABSTRACT TRUNCATED AT 250 WORDS)
Marchlinski et al. (Sun,) conducted a observational in Ventricular tachycardia (n=18). Procainamide vs. Baseline (before procainamide) was evaluated on Correlation between percent change in QRS duration at shorter paced cycle length and percent change in VT cycle length (r = 0.84, p=<0.001). Procainamide-induced percent changes in QRS duration at shorter paced cycle lengths significantly correlated with percent changes in ventricular tachycardia cycle length (r = 0.84, p<0.001).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: