May 29th, 2014

Large Study Uncovers New Details About the Role of Hypertension in CVD

Although high blood pressure has long been recognized and studied as a cardiovascular risk factor, a large new study published in the Lancet provides a more detailed, granular view of the specific role of different forms of hypertension.

Eleni Rapsomaniki and colleagues in the U.K. analyzed data from 1.25 million people without existing cardiovascular disease age 30 and older. An important, and perhaps surprising, new finding is that high blood pressure was not a simple monolithic cardiovascular risk factor. Instead, the researchers found that different types of hypertension at different stages of life had different cardiovascular effects.

“Our findings do not support the widely held assumptions that systolic and diastolic pressure have similar strong associations with the occurrence of all cardiovascular diseases across a wide age range,” said Rapsomaniki, in a Lancet press release.

An elevated systolic BP was strongly linked to intracerebral hemorrhage, subarachnoid hemorrhage, and stable angina, but had only a weak association with abdominal aortic aneurysm (AAA). Pulse pressure (systolic pressure minus diastolic pressure), by contrast, had an inverse correlation with AAA but was a strong predictor of peripheral arterial disease. In accord with many studies over the last few decades, diastolic blood pressure was a less powerful predictor of most cardiovascular diseases than systolic pressure, though it was also a strong predictor of AAA. The results, the authors write, “support the shift in guideline focus in recent years from the importance of diastolic towards the greater importance of systolic pressure in people aged 60 years and older.”

The researchers found no evidence for a J-shaped curve found in some previous studies showing that the lowest blood pressure levels were associated with increased risk. Instead, people in the new study with the lowest blood pressure levels (90-114 mm Hg systolic and 60-74 mm Hg diastolic) had the lowest risk for cardiovascular disease.

For younger patients, the negative effects of hypertension were largely due to an increased risk for coronary artery disease. For older patients, heart failure was the bigger risk.

The findings may also support the early use of antihypertensive treatment in younger people with mild blood pressure elevations. This topic has provoked “substantial debate,” but, the authors write, “in the absence of long-term randomized trials, our estimates of lifetime risk and cardiovascular disease-free years of life lost provide epidemiological evidence of substantial morbidity associated with raised blood pressure, irrespective of the starting baseline risk.”

Although current therapies have helped blunt the impact of hypertension, the authors note that a 30-year-old with hypertension has a 63% lifetime risk of developing cardiovascular disease, compared with 46% in a person without high blood pressure.




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