Acute changes in left ventricular diastolic function: Cigarette smoking versus nicotine gum

Background: Echocardiographic evidence of diastolic dysfunction has been demonstrated during acute cigarette smoking in patients with coronary artery disease. Similar studies in healthy patients have shown conflicting results. Furthermore, it is unclear whether nicotine or some other cigarette-related substance is responsible for these observations. Hypothesis: The purpose of the study was to confirm or refute acute effects of cigarette smoking on diastolic function in healthy patients and to compare diastolic effects of a cigarette to smokeless nicotine delivery (nicotine gum). Methods: In all, 27 healthy volunteers were self-assigned into one of two cohorts. A baseline echocardiogram was performed in all patients. The first cohort proceeded to smoke a cigarette and the second to chew a piece of nicotine gum. Within minutes after exposure, another echocardiogram was performed. Traditional measures of diastolic function were compared before and after substance exposure by paired t-tests. Results: The cigarette cohort showed echocardiographic evidence of diastolic dysfunction after smoking. The E: A ratio (time integral) decreased from 2.95 to 2.22 (p < 0.002). Atrial reversal pulmonary velocity, atrial reversal duration, and color flow propagation all showed statistically significant alterations (p < 0.05). The nicotine gum cohort showed no change in traditional diastolic parameters. Conclusions: Diastolic function is impaired during acute exposure to cigarette smoke but unchanged after exposure to nicotine gum. It is therefore unlikely that nicotine alone is responsible for cigarette-induced acute diastolic dysfunction.