The concept of LIFETIME cardiovascular disease (CVD) risk is beautifully demonstrated in the study published online January 26, 2015 in Circulation .
Fifty-five-year-olds who had prolonged moderately elevated non–HDL (total atherogenic lipoproteins) levels (>160 mg/dL/ 4.0 mmol/L) when they were young adults were much more likely than their peers to have coronary heart disease by the time they were 70. In an analysis based on the Framingham Offspring Cohort the risk of cardiovascular disease (defined as myocardial infarction, angina, coronary insufficiency, or death from CVD) increased with exposure to elevated non-HDL levels in a dose-dependent way.
Specifically, during follow-up, 16.5% of the middle-aged adults who had abnormal atherogenic lipoproteins in the past 11 to 20 years developed CVD, but only 8.1% of those with elevated non-HDL in the past 1 to 10 years developed CVD. In contrast among the adults without elevation of non-HDL, only 4.4% developed CVD.
Having decades of exposure to what many would consider to be mild to moderately elevated atherogenic lipoproteins is associated with a significantly elevated risk of cardiovascular disease. Thus, the way we think about smoking in terms of pack-years, we should be thinking about ‘atherogenic lipid-years’ [of exposure to high non-HDL].
For young adults, we really need to remember that the foundation for cardiovascular disease is being laid in our 20s, 30s, and 40s, so aggressive risk-factor modification at that age is really important. For middle-aged adults, “in the same way that a 55-year-old with a family history of cardiovascular disease [or] an increased coronary calcium score would be considered higher risk, we should take into consideration the duration of exposure to high non-HDL . . . to stratify risk.”
Decades of High Atherogenic Lipoproteins: A New CVD Risk Factor?
Atherosclerosis develops slowly over many years starting in childhood, and the effects of prolonged exposure to elevated atherogenic lipoproteins in young adulthood have previously not been well-defined. This research group examined data from 1478 individuals in the offspring cohort of the Framingham Heart Study who were approximately 55 years old and did not have a history of CVD when they were enrolled during 1987 to 1998.
Participants were stratified into three groups based on hyperlipidaemia (non–HDL >160 mg/dL/ 4.0 mmol/L) at enrolment. A total of 512 participants had no hyperlipidaemia; 389 participants had 1 to 10 years of hyperlipidaemia; and 577 had 11 to 20 years of hyperlipidaemia.
Only 85 participants (5.8%) were on lipid-lowering treatment at baseline.
During a median follow-up of 15 years, there were 136 cardiac events. The unadjusted risk of CVD doubled for every 10 years of exposure to hyperlipidaemia during age 35 to 55 (HR 2.0, 95% CI 1.63–2.45 per decade of hyperlipidaemia).
The association was attenuated but remained statistically significant after adjustment for sex, age, systolic blood pressure, antihypertensive therapy, smoking status, HDL, diabetes, and non–HDL cholesterol at baseline (adjusted HR 1.39, 95% CI 1.05–1.85 per decade of hyperlipidaemia). The association also remained significant after adjustment for lipid-lowering–therapy use at baseline and follow-up.
Based on the 2013 ACC/AHA Cholesterol Guidelines (using the 10-year CVD risk threshold of >7.5%), among the 55-year-old adults who had been exposed to high non-HDL for 11 to 20 years, 15.1% would have met the criteria for statin therapy at age 40 and 34.8% would have met criteria at age 50. However, this study was not designed to determine whether early statin intervention in young adults “on the hyperlipidaemia trajectory” would decrease future CVD risk.
However, it’s certainly not a stretch to say that at least adults in their 50s who have had long-term exposure to high atherogenic non-HDL (total ApoB) should be considered for statin therapy, and there are [randomized clinical trial] data to support the efficacy in that group.
This study used non–HDL cut-offs, since HDL was measured directly whereas LDL was calculated. Typically, non–HDL is 30 mg/dL/ 0.75 mmol/L higher than LDL, and the researchers found similar results using a LDL level of >130 mg/dL/ 3.2 mmol/L.
Individuals who had average non–HDL levels during the preceding 20 years that were below 125 mg/dL/ 3.1 mmol/L had a similar low risk of CVD, and those with levels above 195 mg/dL/ 4.8 mmol/L had a similar high risk of CVD. For every 10-point increase in non–HDL between 125 and 195 mg/dL, there was a 33% increased risk of CVD.
This begs the question as to what constitutes the normal range of non-HDL but in my hands I aim to keep atherogenic lipoproteins (non-HDL or total Apo B) less than 120 mg/dL/ 3.0 mmol/L or 0.8 for Apo B.
Nevertheless, this study identifies adults who may benefit from more aggressive primary prevention and again flies in the face of those sceptics who treat (atherogenic) lipoproteins with no respect.
These findings suggest that adults with longstanding moderate elevations in non–HDL levels should be added to those already identified by the current guidelines as candidates for an informed patient-physician discussion about appropriate lipid-management strategies to reduce future risk of heart disease.
- Navar-Boggan A, Peterson E, D’Agostino R, et al. Hyperlipidaemia in young adulthood increases long-term risk of coronary heart disease. Circulation 2015