Key result
Procainamide significantly increased mean QRS width compared to the control state across multiple paced cycle lengths, including an 18% increase at 600 ms (P<0.01).
Why the study?
The effects of procainamide on cycle length-dependent changes in normal and abnormal intraventricular electrograms in patients with prior myocardial infarction were not well characterized.
Does procainamide alter cycle length-dependent changes in intraventricular electrograms in patients with prior myocardial infarction?
Does procainamide alter cycle length-dependent changes in intraventricular electrograms in patients with prior myocardial infarction?
Procainamide significantly increases QRS width in a cycle length-dependent manner in patients with prior myocardial infarction.
Procainamide accentuates cycle length-dependent QRS widening post-MI; leaves open relevance for arrhythmia risk or dosing.
The effect of procainamide (mean concentration 9.1 +/- 2.0 micrograms/ml) on cycle length-dependent changes in electrographic characteristics was determined in 10 patients with prior myocardial infarction. Intracardiac bipolar electrograms were recorded from an abnormal left ventricular site in the distribution of prior (greater than 6 month) myocardial infarction and from a normal right ventricular site. Pacing was performed for 15 beats from the right ventricular apex at cycle lengths of 600 (or 500), 400 and 300 ms. In the control state, the QRS width, the normal electrogram and in 9 of the 10 patients the abnormal electrogram did not change with decreasing cycle lengths. After procainamide the mean QRS width increased from 203 +/- 32 to 240 +/- 50 ms (+18%, p less than 0.01) at a paced cycle length of 600 (or 500) ms, from 198 +/- 34 to 245 +/- 59 ms (+24%, p less than 0.01) at a paced cycle length of 400 ms and from 197 +/- 36 to 258 +/- 67 ms (+31%, p less than 0.01) at a paced cycle length of 300 ms.(ABSTRACT TRUNCATED AT 250 WORDS)
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Schmitt et al. (1988) studied prior myocardial infarction (n=10). Procainamide vs. control state was evaluated on mean QRS width at a paced cycle length of 600 (or 500) ms (+18%, p=<0.01). Procainamide significantly increased mean QRS width compared to the control state across multiple paced cycle lengths, including an 18% increase at 600 ms (P<0.01).
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