Control subjects had a higher mean compression rate both immediately ( @ -LSB- standard deviation -LCB- SD -RCB- = @ -RSB- vs. @ -LSB- SD = @ -RSB- cpm ; @ % confidence interval -LSB- CI -RSB- of mean difference @-@ ; p = @ ) and at follow-up ( @ -LSB- SD = @ -RSB- vs. @ -LSB- SD = @ -RSB- cpm ; @ % CI of mean difference @-@ ; p = @ ) .