Indoor passive smoking: its effect on cardiac performance.

We studied 19 nonsmoker male volunteers, 9 healthy (mean age 30.5 +/- 8.5), and 10 with previous myocardial infarction (mean age 53.8 +/- 5.3), who underwent exercise stress testing twice: in a smoke-free environment and in a smoking environment (carbon monoxide concentration 30-35 ppm). We measured peak exercise power, time to recovery of pre-exercise heart rate, expired concentration of carbon monoxide and plasma carbon monoxide. Obtained data were compared by using t-test. P less than 0.05 was statistically significant. Mean data observed in healthy people were as follows. Peak exercise power 220 +/- 30 watts in a smoking environment versus 220 +/- 30 in a smoke-free environment (P greater than 0.05). Time to recovery of pre-exercise heart rate 19 +/- 4 minutes in a smoking environment versus 8.5 +/- 4 in a smoke-free environment (P less than 0.01). Expired concentration of carbon monoxide before exercise 2.3 +/- 2.01 ppm versus 8.5 +/- 1.6 (P less than 0.01) after exercise in a smoking environment, and 2.3 +/- 2 ppm before exercise versus 2.1 +/- 1.9 after exercise in a smoke-free environment (P less than 0.05). Plasma carbon monoxide before exercise 1.4 +/- 0.2% versus 1.7 +/- 0.4 after exercise in a smoking environment (P greater than 0.05), and 1.2 +/- 0.4% before exercise versus 1.2 +/- 0.4 in a smoke-free environment (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)