Ischaemic heart disease

Association of plasma uric acid with ischaemic heart disease and blood pressure: mendelian randomisation analysis of two large cohorts.

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Abstract

Objectives To assess the associations between both uric acid levels and hyperuricaemia, with ischaemic heart disease and blood pressure, and to explore the potentially confounding role of body mass index.

Design Mendelian randomisation analysis, using variation at specific genes (SLC2A9(rs7442295) as an instrument for uric acid; and FTO (rs9939609), MC4R(rs17782313), and TMEM18 (rs6548238) for body mass index).

Setting Two large, prospective cohort studies in Denmark.

Participants We measured levels of uric acid and related covariables in 58 072 participants from the Copenhagen General Population Study and 10 602 from the Copenhagen City Heart Study, comprising 4890 and 2282 cases of ischaemic heart disease, respectively.

Main outcome Blood pressure and prospectively assessed ischaemic heart disease.

Results Estimates confirmed known observational associations between plasma uric acid and hyperuricaemia with risk of ischaemic heart disease and diastolic and systolic blood pressure. However, when using genotypic instruments for uric acid and hyperuricaemia, we saw no evidence for causal associations between uric acid, ischaemic heart disease, and blood pressure. We used genetic instruments to investigate body mass index as a potentially confounding factor in observational associations, and saw a causal effect on uric acid levels. Every four unit increase of body mass index saw a rise in uric acid of 0.03 mmol/L (95% confidence interval 0.02 to 0.04), and an increase in risk of hyperuricaemia of 7.5% (3.9% to 11.1%).

Conclusion By contrast with observational findings, there is no strong evidence for causal associations between uric acid and ischaemic heart disease or blood pressure. However, evidence supports a causal effect between body mass index and uric acid level and hyperuricaemia. This finding strongly suggests body mass index as a confounder in observational associations, and suggests a role for elevated body mass index or obesity in the development of uric acid related conditions.

Source:BMJ

 

Breast Irradiation and Increased Risk for Ischemic Heart Disease: New Data Emerge.

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A case-control study in the New England Journal of Medicine provides new information on the link between breast irradiation and increased risk for ischemic heart disease.

Using national registries, researchers in Sweden and Denmark studied nearly 2200 women who underwent radiotherapy for breast cancer between 1958 and 2001; roughly 1000 who subsequently had a major coronary event were matched with 1200 controls.

The rate of coronary events increased with the mean estimated dose of radiation to the heart. The risk increase was observed within 5 years after treatment and lasted for at least 20 years. The absolute risk for coronary events was particularly high for women who had preexisting cardiac risk factors.

In Journal Watch Oncology and Hematology, William Gradishar concludes: “Efforts to provide women with the option of breast conservation should not be abandoned, but for select women with very significant cardiac risk factors … a mastectomy might be a better option.”

Source: NEJM