Effects of Smoking Cessation on Blood Pressure and Heart Rate Variability in Habitual Smokers

—We investigated the effects of 1-week of smoking cessation on ambulatory blood pressure, heart rate, and heart rate variability in 39 normotensive male habitual smokers (mean±SEM, 32.5±1.0 years). The ambulatory blood pressure, heart rate, and ECG R-R intervals were measured during a 24-hour period with a portable recorder (TM-2425) on the last day of 1-week smoking and nonsmoking periods. The order of the 2 periods was randomized. In the smoking period, the subjects were instructed to smoke cigarettes according to their usual smoking patterns. A power-spectral analysis of R-R intervals was performed to obtain the low-frequency (LF) and high-frequency (HF) components. The percentage of differences between adjacent normal R-R intervals >50 milliseconds (pNN50) was used as a time-domain measure of heart rate variability. The 24-hour ambulatory blood pressure was significantly lower in the nonsmoking period than in the smoking period, by 3.5±1.1 mm Hg systole [P <0.01] and by 1.9±0.7 mm Hg diastole [P <0.05], whereas the nighttime blood pressure did not differ significantly between the 2 periods. The 24-hour heart rate was significantly lower in the nonsmoking period than in the smoking period, by 7.3±1.0 beats/min (P <0.0001). The pNN50 and the 24-hour HF component were significantly higher in the nonsmoking period than in the smoking period (P <0.0001 for each). The plasma norepinephrine and epinephrine concentrations were significantly lower in the nonsmoking period than in the smoking period (P <0.05 for each). These results demonstrate the substantial and immediate benefits of smoking cessation on these cardiovascular indices.