in 4 patients in whom episodes of atrial fibrillation could be compared before and after verapamil , the drug decreased the average r-r interval from a control value of 327 +/- 27 ms to 282 +/- 28 ms ( p less than 0.05 ) and decreased the shortest r-r interval between preexcited beats from a control value of 237 +/- 21 ms to 209 +/- 18 ms ( p less than 0.05 ) .
C0004238
atrial
C0042523
verapamil