Hypertension and coronary heart disease. Is there a J-curve for diastolic blood pressure?

Abstract

While some studies pointed to the possible existence of a J curve of diastolic blood pressure, other studies did not confirm such a relationship. A recent retrospective analysis of INVEST involving 22,576 patients with hypertension and coronary heart disease has shown the risk of the primary endpoint had had a J-curve relationship with diastolic blood pressure (BP) peaking at a BP of 119/84 mmHg. A J-curve relationship was particularly obvious between diastolic BP and the risk of fatal and non-fatal myocardial infarction. A J-curve relationship for the risk for fatal and non-fatal stroke was only suggested. Compared with the incidence of myocardial infarction in patients with a diastolic BP of 70-90 mmHg, that in patients with a diastolic BP of 60-70 mmHg (on therapy) was double, and even triple in individuals with a diastolic BP < 60 mmHg. These retrospective findings made in CHD patients receiving antihypertensive therapy do not document a causal relation nor do they allow concluding that the excess fall in diastolic BP caused by antihypertensive therapy results in excess morbidity and mortality. Regrettably, there is no prospective randomized study evaluating the effect of antihypertensive therapy aimed at reaching low diastolic BP levels, i. e., decreases below 80, 70, and 60 mmHg. Such a study would be ideally conducted in patients with isolated systolic hypertension. Though controversial, the above findings reported in this review suggest low diastolic BP levels may be associated with an increased cardiovascular risk. Of the three potential interpretations of a J-curve relationship between diastolic BP and coronary events, the most likely one is highlighting the fact an increased risk is present particularly in elderly patients with isolated systolic hypertension. There has been no study to date demonstrating a decrease in systolic BP in the elderly within a range of 140-159 mmHg has a beneficial effect on morbidity and mortality, with a goal systolic BP level below 140 mmHg. The recommendations of goal levels < 140 mmHg even in the elderly are particularly based on the observational studies. It is our impression that, given the current controversial J-curve data, and the relationship between diastolic BP and coronary events, it is appropriate to give utmost attention to patients with isolated systolic hypertension whose diastolic BP falls below 65 mmHg while receiving therapy. In such situations, one should not insist on reaching goal systolic BP levels. This should presumably apply mostly to elderly patients with coronary heart disease.