ASSOCIATION OF CIGARETTE-SMOKING WITH CHRONOTROPIC INCOMPETENCE AND PROGNOSIS IN THE FRAMINGHAM HEART-STUDY

Background In this study, we sought to determine whether cigarette smo king is associated with chronotropic incompetence and to explore progn ostic implications of this association. Methods and Results Members of the Framingham Offspring Study (1468 men and 1642 women) underwent gr aded exercise. Chronotropic incompetence was assessed in two ways: (1) failure to achieve an age-predicted target heart rate and (2) a low c hronotropic index, a heart rate response measure that accounts for eff ects of age, resting heart rate, and physical fitness. Smokers were mo re likely to fail to reach target heart rate than were nonsmokers (men , 25% versus 15%, odds ratio [OR], 1.97; 95% confidence interval [CI], 1.51 to 2.56; women, 32% versus 18%; OR, 2.10; 95% CI, 1.63 to 2.61) and were more likely to have a low chronotropic index (men, 17% versus 12%; OR, 1.50; 95% CI, 1.12 to 2.03; women, 17% versus 8%; OR, 2.28; 95% CI, 1.68 to 3.09). These associations persisted after adjustment f or age, cardiovascular risk factors, pulmonary function, and ST-segmen t response to graded exercise. During 8 years of follow-up, there were 48 deaths and 90 incident coronary heart disease events among the men . After adjust ment for the same confounders, men who were smokers and failed to achieve target heart rate were at particularly high risk fo r death (adjusted relative risk [RR], 2.45; 95% CI, 1.14 to 5.24) and for coronary heart disease (adjusted RR, 4.92; 95% CI, 2.84 to 8.53). There were too few end points in women for analysis. Conclusions In th is population-based cohort, cigarette smoking was predictive of chrono tropic incompetence. Male smokers who manifested chronotropic incompet ence were at particularly high risk for death and coronary heart disea se events.