Relation Between Family History of Premature Coronary Artery Disease and the Risk of Death in Patients With Coronary Artery Disease.

Family history (FHx) of premature coronary artery disease (CAD) is a risk factor for development of incident cardiovascular disease. However the association between FHx and outcomes in patients with established CAD is unclear. We followed 84,373 patients with angiographic CAD enrolled in the inclusive Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease registry between April 2002 and March 2013. Overall, 25,566 (30%) self-reported an FHx of CAD, defined as a first-degree relative with premature CAD (men, age <55 years; women, age <65 years). We tested the association between FHx and all-cause mortality using multivariable Cox proportional hazards regression. After adjusting for baseline differences in clinical characteristics, indication, and extent of CAD, FHx was associated with reduced all-cause mortality over a median 5.6 years in follow-up (hazard ratio [HR] 0.77 [95% CI 0.73 to 0.80]). The magnitude of this protective association was weaker in those with versus without a previous myocardial infarction (HR 0.87 [95% CI 0.81 to 0.93] versus 0.72 [0.69 to 0.76], interaction p <0.0001) and slightly stronger in those presenting with versus without an acute coronary syndrome (HR 0.74 [0.70 to 0.79] versus 0.80 [0.75 to 0.85], interaction p = 0.08). There was attenuation of association with increasing age, but FHx remained protective even in those aged older than 80 years (HR 0.86 [0.77 to 0.95]). In conclusion, in patients with angiographic CAD, self-reported FHx of premature CAD is associated with improved long-term survival rate, independent of clinical characteristics, mode of presentation, and extent of disease. Further investigation of potential patient- and system-level mediators of this seemingly paradoxical relation is required.