Lowering blood pressure to prevent myocardial infarction and stroke: A new preventive strategy

Abstract

Objectives: This study aimed to investigate the screening performance of measuring blood pressure and other variables in identifying those who willdevelop, or die from, ischemic heart disease and stroke and too quantify by howmuch drugs that lower blood pressure will reduce the risk of ischemic heart disease and stroke in those designated “screen positive.”

Objectives: This study aimed to investigate the screening performance of measuring blood pressure and other variables in identifying those who will develop, or die from, ischemic heart disease and stroke and too quantify by how much drugs that lower blood pressure will reduce the risk of ischemic heart disease and stroke in those designated “screen positive.”

Data sources: Used were MEDLINE, Cochrane collaboration and Web of Science databases; Stroke registries; Health Survey for England; Office of National Statistics; BUPA (British United Provident Association) study.

Review methods: Relevant cohort studies and randomized trials were identified and analyzed. Statistical analysis was used to determine drug efficacy and adverse effects.

Results: Lowering blood pressure by 5 mm Hg diastolic reduces the risk of stroke by an estimated 34 percent and ischemic heart disease by 21 percent from any pretreatment level; there is no threshold. These estimates, from cohort studies, have been corroborated by the results of randomized trials in persons with high, average, and below average levels of blood pressure. Despite its importance in causing cardiovascular disease, blood pressure is a poor predictor of cardiovascular events. Its poor screening performance is illustrated by the findings that, in the largest cohort study, persons in the top 10 percent of the distribution of systolic blood pressure experienced only 21 percent of all ischemic heart disease events and 28 percent of all strokes at a given age. Combining several reversible risk factors adds little to the screening performance of blood pressure alone; for example, the 25 percent of men 55–64 years of age at highest computed risk ([gE ]1 percent) experience only 46 percent of all ischemic heart disease events. The main methods of screening should be to identify all persons with a history of cardiovascular disease events (for example, identifying patients at the time of hospital discharge after a first myocardial infarction detects 50 percent of all heart disease deaths in a population at a false-positive rate of 12 percent), and to use a person's age. Identifying everyone with a history of myocardial infarction or stroke in a population and everyone 55 years of age or older would include 98 percent of all deaths from ischemic heart disease and stroke. The five main categories of blood pressure-lowering drugs, thiazides, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor antagonists, and calcium channel blockers, significantly reduce blood pressure from all pretreatment levels, although the extent of the blood pressure reduction increased with pretreatment blood pressure. The reductions were similar at standard dose for the five categories: average reduction was 9.1 systolic and 5 diastolic. The effect of combinations of two drugs on blood pressure was additive. No effect of age was apparent, given blood pressure. There were no serious metabolic consequences of using these drugs in standard dose.

Conclusions: The evidence presented indicates that three drugs in combination may reduce stroke by approximately two thirds and ischemic heart disease by half. The report suggests that the term hypertension should be avoided, because it is not a disease and it suggests another category (normotensives) who would not benefit from lowering blood pressure. Blood pressure reduction using combinations of safe, well-established drugs is effective in preventing cardiovascular events. It is, therefore, suggested that such preventive therapy be considered more widely in people who, by virtue of existing disease or simply age, are at risk of a heart attack or stroke regardless of initial blood pressure.