Inevitable or preventable? High blood pressure linked to mitral regurgitation

About two-thirds of mitral regurgitation cases are classified as degenerative, implying little can be done to prevent them as people age. But a new study in PLOS Medicine suggests high blood pressure could be a modifiable risk factor for the common heart valve disorder.

Using 25 years of electronic health records, researchers from the United Kingdom tracked about 5.5 million patients with no known cardiovascular or valve disease at baseline. Approximately 30,000 new cases of mitral regurgitation were observed over the 10-year follow-up.

Each 20 millimeters of mercury increase in systolic blood pressure (SBP) was associated with a 26 percent greater risk of mitral regurgitation, and each 10 mm/Hg increase in diastolic blood pressure (DBP) was associated with a 24 percent greater risk of mitral regurgitation. Both associations varied by age group, with stronger association seen in younger groups.

"Our research suggests this common and disabling valve disorder is not an inevitable consequence of aging, as previously assumed, but may be preventable," Kazem Rahimi, MD, lead study author and cardiologist at the University of Oxford, said in a press release.

"Given the large and growing burden of mitral valve disease, particularly among older people, we believe these findings are likely to have significant implications for medical policy and practice around the world."

Rahimi and colleagues noted a previous study showed a positive association between hypertension and mitral regurgitation, but they claimed this was the first longitudinal study examining the relationship.

Even after adjusting for secondary mitral regurgitation from diseases that affected the left ventricle—MI, ischemic heart disease, cardiomyopathy and heart failure—the researchers observed a 22 percent higher risk per 20 mm/Hg of SBP.

“Given that increased BP correlates with higher left ventricular pressure, and this, in turn, exposes the mitral valve to higher physical stress, it seems plausible that long-term exposure to higher BP could also lead to structural and functional changes of the mitral valve,” they wrote.

The authors acknowledged their work “may not establish causation beyond doubt,” but said future studies could test whether BP-lowering interventions reduce the risk of mitral regurgitation.

Rahimi and colleagues didn’t detect a significant association between blood pressure and mitral stenosis.