ASCVD Risk Stratification Using Family History
—Validated family history is a key risk factor for ASCVD and may be the largest contributor to risk. An accurate family history of ASCVD can help determine the need for measuring CAC--and ultimately the need for lipid-lowering therapy.
Atherosclerotic cardiovascular disease (ASCVD) has many risk factors, some of which cannot be changed, and some of which are more easily modifiable. One of the major non-modifiable risk factors for ASCVD is family history.1 At least one study in the past has suggested that, especially when other important risk factors are accounted for, even a history of a single first-degree relative of any age with a history of coronary heart disease (CHD) identifies the patient as having an increased risk of CHD.2
Nevertheless, family history is not part of all CHD risk assessment algorithms or calculators. This may have occurred for several reasons, such as bias in recalling family history, as well as its variable predictive value, depending on whether the prediction is for premature or later-onset events.1 Dr. Marina Sharif and colleagues, the authors of “Power of the pedigree: the family history variable for ASCVD risk stratification,” published online by the American College of Cardiology, Latest in Cardiology section, state that using any first-degree relative with ASCVD may be as good a predictor of ASCVD events as family history of only premature events.
In addition to family history of CHD predicting an individual’s risk of CHD, family history can also be used in the management of high cholesterol. The American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines’ Guideline on Management of Blood Cholesterol recommends classifying individuals who are 40-75 years of age, who have an LDL-C ≥ 70 mg/dL and < 190 mg/dL as either borderline (5% to < 7.5%) or intermediate (≥ 7.5% to 20%) risk based on the . Those individuals are thought to be at increased risk. It is then recommended that history of risk factors be obtained; a positive family history would support starting treatment with a statin, as there is a higher lifetime risk of ASCVD. That guideline recommends that the family history be a history of premature ASCVD.1 In young adults with persistent moderate hypercholesterolemia, family history of premature ASCVD may indicate the need for treatment with a statin.1 Negative clinical markers have also been found to be helpful, as absence of family history of CHD was found to be correlated with lower risk of CHD.1,3
Coronary artery calcium (CAC) can also be used to aid in determining whether or not to begin statin therapy. A CAC score of 1 to 99 would indicate that statin therapy should be started, particularly in patients 55 years of age or older. If the CAC is 0, there is a low risk for ASCVD for the next 10 years, and, if there are no other risk factors, statin therapy can be deferred. If the CAC is > 100, there is a 10-year-ASCVD-risk of ≥ 7.5%, which is the cut-off for starting statin therapy. CAC scans are not recommended for individuals with a family history of CHD because they are already at risk for ASCVD events even without an elevated CAC. However, if the patient is low risk, but has a strong family history of premature ASCVD, a CAD would make sense to evaluate their need for statin therapy.1
CHD risk assessment for prevention of ASCVD
Assessment of CHD risk for ASCVD prevention involves evaluating genetics, social habits, and environment and then identifying patients who would benefit from medications. Validated family history is a large contributor to this evaluation, especially if that family history includes premature ASCVD. Other risk factors, such as hypertension, diabetes, and hypercholesterolemia should also be addressed.
The authors concluded that “[r]isk assessment should start with the assessment of traditional cardiovascular risk factors and calculation of the 10-year risk of ASCVD with the PCE. Among those at borderline and intermediate ASCVD-risk, the presence of a [family history] of premature-ASCVD may identify higher risk patients, supporting a decision to initiate or intensify statin pharmacotherapy. For…patients [with low-risk family history], the presence of CAC … can further refine risk to guide the clinician-patient risk discussion to patients for whom preventive pharmacotherapy may be useful.”
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