Higher Fitness Is Strongly Protective in Patients with Family History of Heart Disease: The FIT Project

Background Cardiorespiratory fitness protects against mortality; however, little is known about the benefits of improved fitness in individuals with a family history of coronary heart disease. We studied the association between cardiorespiratory fitness and risk of incident coronary heart disease and all-cause mortality, hypothesizing an inverse relationship similar to individuals without a family history of coronary heart disease. Methods We included 57,999 patients (aged 53 ± 13 years; 49% were female; 29% were black) from the Henry Ford Exercise Testing (FIT) Project. Cardiorespiratory fitness was expressed in metabolic equivalents of task based on exercise stress testing. Family history was determined as self-reported coronary heart disease in a first-degree relative at any age. We used Cox proportional hazards models adjusted for demographics and cardiovascular disease risk factors to examine the association between cardiorespiratory fitness and risk of incident coronary heart disease and mortality over a median (interquartile range) follow-up of 5.5 (5.6) and 10.4 (6.8) years, respectively. Results Overall, 51% reported a positive family history. Each 1-unit metabolic equivalent increase was associated with lower incident coronary heart disease and mortality risk regardless of family history status. The hazard ratio and 95% confidence interval for a negative family history and a positive family history were 0.87 (0.84-0.89) and 0.87 (0.85-0.89) for incident coronary heart disease and 0.83 (0.82-0.84) and 0.83 (0.82-0.85) for mortality, respectively. There was no significant interaction between family history and categoric cardiorespiratory fitness, sex, or age (P >.05 for all). Conclusions Higher cardiorespiratory fitness is strongly protective in all patients regardless of family history status, supporting recommendations for regular exercise in those with a family history.