Cardiovascular Family History Increases the Risk of Disease Recurrence After a First Myocardial Infarction

Background Family history of atherosclerotic cardiovascular disease (ASCVD) is easily accessible and captures genetic cardiovascular risk, but its prognostic value in secondary prevention is unknown. Methods and Results We followed 25 615 patients registered in SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) from their 1-year revisit after a first-time myocardial infarction during 2005 to 2013, until December 31, 2018. Data on relatives, diagnoses and socioeconomics were extracted from national registers. The association between family history and recurrent ASCVD was studied with Cox proportional-hazard regression, adjusting for risk factors and socioeconomics. A family history of ASCVD was defined as hospitalization due to myocardial infarction, angina with coronary revascularization, stroke, or cardiovascular death in ≥1 parent or full sibling, with early-onset defined as disease-onset before 55 years in men and 65 in women. The additional discriminatory value of family history to Thrombolysis in Myocardial Infarction Risk Score for Secondary Prevention was assessed with Harrell's C-index difference and reclassification was studied with continuous net reclassification improvement. Family history of early-onset ASCVD in ≥1 first-degree relative was present in 2.3% and was associated with recurrent ASCVD (hazard ratio [HR] 1.31; 95% CI, 1.17-1.47), fully adjusted for risk factors (HR, 1.22; 95% CI, 1.05-1.42). Early-onset family history improved the discriminatory ability of the Thrombolysis in Myocardial Infarction Risk Score for Secondary Prevention, with Harrell's C improving 0.003 points (95% CI, 0.001-0.005) from initial 0.587 (95% CI, 0.576-0.595) and improved reclassification (continuous net reclassification improvement 2.1%, P<0.001). Conclusions Family history of early-onset ASCVD is associated with recurrent ASCVD after myocardial infarction, independently of traditional risk factors and improves secondary risk prediction. This may identify patients to target for intensified secondary prevention.