Low HDL cholesterol: an important risk factor in heart attack patients

Data from the American Heart Association’s Get With The Guidelines study highlight the need for improvement in the management of low high density lipoprotein (HDL) cholesterol. More than 50% of patients hospitalised for heart attack had an HDL cholesterol value less than 40 mg/dL. The study was published in the January issue of The American Heart Journal. The report was reviewed by HDL Forum Editor Professor Philip Barter.

 Sachdeva A, Cannon CP, Deedwania PC et al. Lipid levels in patients hospitalized with coronary artery disease: an analysis of 136,905 hospitalizations in Get With The Guidelines. Am Heart J 2009;157:111-7.e2.

 The Get With The Guidelines program was set up to support improvement in the quality of care in patients with cardiovascular disease using web-based management tools. The current report was based on a database of patients hospitalised for coronary artery disease (CAD) in 541 centres across the USA over the period 2000-2006, and with documented lipid levels within the first 24 hours of admission. Admission lipid levels were categorised on the basis of the following:

For low density lipoprotein (LDL) cholesterol: <70, 70-100, 100-130, 130-160 and >160 mg/dL

For HDL cholesterol: <40, 40-60 and >60 mg/dL

For triglycerides: <150 and >150 mg/dL.

 Researchers analysed data from 231,986 patients, of whom 59% (136,905) patients had admission lipid levels. Cardiovascular risk factors were common amongst this group: 54% had hypertension, 26% had diabetes and 30% were smokers. Amongst patients with a history of heart attack (16.5%), 46% had previously documented coronary heart disease, other atherosclerotic disease or diabetes (fig 1).

 

 

The most common admission diagnosis (in 79% of patients) was acute coronary syndromes (either ST-segment or non-ST segment elevation myocardial infarction). Lipid-modifying treatment was received by 21% of patients before admission, although this proportion was higher in patients with a history of cardiovascular disease or diabetes (29% vs. 14% in those without a history of these conditions).

 Importantly, in more than one-half of patients (54.6%) hospitalised for heart attack, HDL cholesterol was <40 mg/dL. Amongst patients with a history of cardiovascular disease or diabetes, low HDL cholesterol was present in 34% of patients with LDL cholesterol values <100 mg/dL, of whom 14% had values <70 mg/dL (fig 2). 

 

 

Among patients without prior cardiovascular disease or diabetes, 72.1% had admission LDL cholesterol levels <130 mg/dL, currently regarded as the target for this group. This suggests that most patients having their first heart attack would not have been targeted for effective preventive measures, based on current guideline criteria.  Of patients with prior cardiovascular disease or diabetes, 56% had LDL cholesterol values <100 mg/dL and 21.9% had values <70 mg/dL (fig 3). In patients receiving lipid-modifying treatment, 64% had admission LDL cholesterol <100 mg/dl and 25% had values <70 mg/dL.

 

Analysis of trends in lipid levels during the study period showed that HDL cholesterol decreased in patients hospitalised for heart attack, from 43 mg/dL in 2000 to 39 mg/dL in 2006 (p<0.0001), possibly due to increasing rates of obesity, diabetes and metabolic syndrome. There was also a small increase in triglyceride levels over time (from 150 to 153 mg/dL, p<0.0001). In contrast, the data show a steady decline in LDL cholesterol levels over time (from 108 to 103 mg/dL, p<0.0001) (fig 4).

 

It is worth highlighting that less than 2% of patients in this cohort had both ideal LDL and HDL cholesterol values. Commenting on these data, Dr Gregg C. Fonarrow, Eliot Corday Professor of Cardiovascular Medicine and Science, David Geffen School of Medicine at UCLA and the principle investigator of the study said: ‘Current guidelines may not be low enough to cut heart attack risk in most who could benefit.’. He also underlined that clinical practice is less than optimal in this group, as only 59% of the cohort had lipid levels checked on admission and only 21% were taking lipid-lowering medication before admission, despite almost half having prior history of cardiovascular disease.


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