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Primary Prevention of Cardio-Vascular Disease
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Assessment and Management of Cardiovascular RiskThe INTER-HEART StudyThis large case-control study, was published in The Lancet in 2004 and suggests that most of the risk of ischaemic cardiac events can be predicted by the measurement of conventional risk factors. These factors seemed to impart the same risk in different populations. This original report assessed the risk of dyslipidaemia by measurement of the Apo-B/Apo-A1 ratio rather than the total cholesterol/HDL ratio. This method of assessing dyslipidaemia may be particularly useful in those with the typical metabolic syndrome profile with low HDL cholestol levels and raised triglycerides with average LDL cholesterol levels. We will await with interest the publication of further data from this study including a paper on dyslipidaemia. Almost thirty thousand cases (those that had had first myocardial infarction) and controls were enrolled in this study, there were slightly more cases than controls. Participants were enrolled from all continents. The study confirmed the increased risk with:
The study also found an increased risk with psychosocial factors (ie stress)- odds ratio 2.67. The study also found a lower risk with:
Smoking and dyslipidaemia account for over two thirds of the global risk of ischaemic heart disease. Combined with the other seven risk factors, these nine risk factors collectively accounted for over 90% of the risk of acute myocardial infarction. They were able to show an exponential increase in risk with increasing cigarrette consumption (with the odds ratio being over 8 for those that smoked more than 40 cigarrettes per day). An exponential increase in risk was also demonstrated for increasing Apo-B/Apo-A1 ratio. Their data are consistent with others showing that those with multiple risk factors had particularly high risk, much higher than that calculated by simple summation of the odds ratios of individual risk factors. These nine risk factors accounted for most of the risk of myocardial infarction in all regions, for males and females. The odds ratio for smoking was the same in different regions. The risk associated with dyslipidaemia was also much the same in different regions with a possibility of the risk being less in Eastern Europe and higher in Africa. When dyslipidaemia is measured using the Apo-B/Apo-A1 ratio, there is no evidence for greater susceptibility amongst Asians. It is entirely possible that different results, for dyslipidaemia, may have been obtained if the total cholesterol/HDL cholesterol ratio had been used- we will await with interest subsequent publications from this study. This study suggests that if these risk factors are modified aggressively then the burden of ischaemic heart disease will be reduced greatly. One assumes that to actually achieve this goal we may have to successfully change people's lifestyle and also set a lower threshold for drug treatment of risk factors. More specifically, I strongly suspect that the threshold set for pharmacological treatment in the New Zealand Guidelines would need to be reset at a lower level. Alternatively, we can continue to search for "emerging risk factors" that help us refine our risk assessment to enable us to target intensive therapy to the higher risk groups. It may be time to consider use measurement of Apo-B levels in selected patients to try to refine risk assessment. Hitesh Patel, Cardiologist Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. The Lancet, September 2004(364): 937 Users should read this document on "copyright" and "conditions of use". |