Effect of various regimens of chronic and acute nicotine exposure on myocardial infarct size in the dog.

Smoking is a risk factor for atherosclerotic coronary heart disease, and the risk increases with increasing numbers of cigarettes smoked. The effect of cigarette smoking on the size of acute myocardial infarction (AMI) has not been evaluated. This study describes the effect of 1 component of tobacco smoke, nicotine, on the size of experimentally induced AMI in closed-chest dogs. Daily exposure to nicotine before AMI increased the volume of infarcted tissue (p less than 0.0001). Acute exposure to nicotine (with prior chronic exposure) resulted in a larger volume of infarcted tissue (p less than 0.0001). Thus, chronic, acute and post-AMI exposure to nicotine has an adverse effect on the volume of subsequent infarcted tissue, and continued exposure after AMI further enlarges infarct size.