HEART-RATE-VARIABILITY DURING THE FIRST MONTH OF SMOKING CESSATION

Background Heart rate variability (HRV) is known to increase after smo king cessation. However, no work has been performed concerning HRV imm ediately after smoking cessation. Methods and Results We studied HRV b efore and from 1 day to 1 month after smoking cessation and also deter mined whether there is a relation between HRV and the withdrawal syndr ome immediately after smoking cessation. We determined HRV by using a two-channel 24-hour ambulatory ECG system before and 1, 2, 3, 7, 14, 2 1, and 28 days after smoking cessation in 20 healthy male volunteers w ho had smoked one or more packs per day for 2 or more years. One day a fter smoking cessation, heart rate decreased significantly, and all 24 -hour time and frequency domain indices of HRV increased except the st andard deviations of the normal R-R intervals and the 5-minute mean R- R. The magnitude of increase in these indices peaked 2 to 7 days after smoking cessation and gradually decreased thereafter. The increase in HRV persisted 1 month after smoking cessation. In the 16 subjects wit h signs of withdrawal syndrome and in the four subjects without eviden ce of withdrawal before and immediately and 1 month after smoking cess ation, HRV increased immediately after smoking cessation and remained elevated after 1 month. Conclusions HRV increases immediately after sm oking cessation and gradually declines thereafter, which suggests that the effect of smoking on autonomic activity rapidly disappears immedi ately after smoking cessation. HRV remained unaffected by the presence or absence of the withdrawal syndrome.