Blood Type May be Factor in Heart Attack Risk

The odds ratio for all coronary events and combined cardiovascular events was found to be significantly higher in carriers of a non-O blood group.

Individuals with a non-O blood type may have a greater risk of heart attack according to results from a new meta-analysis which assessed over 1 million subjects. The study results were presented at the ‘Heart Failure 2017′ conference in Paris, France.

Researchers assessed nine studies which included a total of 1,362,569 individuals. The studies reported on O and non-O blood groups and incidence of cardiovascular events defined as myocardial infarction, coronary artery disease, ischemic heart disease, heart failure, cardiovascular events and cardiovascular mortality.

Analysis of combined cardiovascular events included 708,276 individuals with non-O blood type and 476,868 with an O blood type, of these 17,449 (2.5%) and 10,916 (2.3%) had events, respectively.  A total of 771,113 individuals with a non-O blood type and 519,743 with an O blood type were included in the analysis of all coronary events. The results showed that 11,437 (1.5%) of the non-O blood group had a coronary event compared to 7,220 (1.4%) in the O blood group. 

The odds ratio for all coronary events and combined cardiovascular events was significantly higher in carriers of a non-O blood group at 1.09 (95% confidence interval [CI] of 1.06–1.13) and 1.09 (95% CI 1.06–1.11), respectively.

Commenting on the results lead author Tessa Kole, a masters student at the University Medical Centre Groningen, said, “We demonstrate that having a non-O blood group is associated with a 9% increased risk of coronary events and a 9% increased risk of cardiovascular events, especially myocardial infarction.”

The authors conducted the research to compare and build upon findings in previous case-control studies – that have a low level of evidence – which proposed that A, B, and AB blood types carry a higher risk of heart attacks. The reason why non-O blood types have greater cardiovascular health risks are unknown, however the authors speculate that it could be due to non-O blood individuals having a higher level of von Willebrand factor in their blood, which is a clotting protein and may be linked to thrombotic events. Further research is needed to shed light on this connection and to ascertain whether the apparent risk for non-O blood type individuals is amenable to treatment, write the researchers.

“In future, blood group should be considered in risk assessment for cardiovascular prevention, together with cholesterol, age, sex and systolic blood pressure,” said Ms. Kole. 

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