Cardiovascular effects of cigarette smoking: ambulatory blood pressure and BP variability.

Cigarette smoking and hypertension are independent risk factors for cardiovascular disease, but the relationship between them is complex. Smoking raises BP acutely, yet in epidemiological studies smokers have lower clinic BP than nonsmokers. To explore this apparent paradox we have compared 24h ambulatory BP profiles and BP variability of smokers, before and after a week's abstention from smoking, and nonsmoking controls. There was no evidence of a significant acute pressor effect from smoking. All three groups had similar ABP profiles but smokers had significantly more variable BP than nonsmokers and variability increased still further after a week's abstention. An increase in BP variability, possibly related to changes in baroreflex sensitivity, is a further mechanism by which smoking may increase cardiovascular risk.