The serum ratio of two types of apolipoprotein – proteins that bind with lipids to form cholesterol and play a role in transporting lipids – is more accurate in predicting cardiovascular risk than cholesterol itself, they say.
The INTERHEART study looked at 12,461 myocardial infarction cases and 14,637 controls. Researchers compared blood fat, lipoprotein and apolipoprotein levels as indicators of MI risk.
The ratio of apolipoprotein B100 (ApoB) to apolipoprotein A1 (ApoA1) accounted for 54% of the risk of MI. The ratio of ‘bad’ to ‘good’ cholesterol accounted for 37%, and the ratio of total to ‘good’ cholesterol accounted for 32%.
The ApoB to ApoA1 ratio was almost twice as effective as cholesterol ratios in predicting MI risk, the authors said.
‘The non-fasting ApoB/ApoA1 ratio was superior to any of the cholesterol ratios for estimation of the risk of acute heart attack in all ethnic groups, in both sexes, and at all ages, and it should be introduced into worldwide clinical practice,’ they said.
Judy O’Sullivan, cardiac nurse at the British Heart Foundation, said the study added weight to the growing evidence that apolipoproteins were a good marker for MI risk.
‘However, it won’t change clinical practice overnight.
We don’t have enough good evidence – or access to suitable technology – to overtake standard cholesterol testing just yet,’ she said.
‘In time though, it is likely that measurement of apolipoproteins will become part of a risk assessment for heart and circulatory disease,’ she added.
The Lancet (2008) 372: 224–233