Arq. Bras. Cardiol. 2025; 122(3): e20250150
Ideal Blood Pressure Levels: So Long the J-Curve, Lower is Better
This Short Editorial is referred by the Research article "Systematic Review of the Effectiveness of Intensive Antihypertensive Treatment Goals: Brazilian Society of Cardiology (SBC) Recommendation".
While hypertension is one of the most well-recognized risk factors for cardiovascular disease, there are no clear universally accepted ideal blood pressure levels. Original data from the Framingham heart study in the 1970s suggested no normality threshold for high blood pressure, indicating that “the lower, the better”, particularly for systolic blood pressure. However, subsequent reanalysis of the same data suggests a J-curve association between diastolic blood pressure and outcomes. Interestingly, the J-curve pattern was restricted to the diastolic blood pressure as the associations of systolic blood pressure with mortality and cardiovascular outcomes have always been linear with no clear threshold at least to levels as low as 90-110 mmHg. Based on such epidemiological data as well as clinical knowledge that lower blood pressure levels may cause symptoms, hypertension guidelines have recommended a parsimonious definition of blood pressure target tailored to the individual patient risk. In the 1970s, the first version of the Joint National Committee treatment was only consistently indicated with diastolic blood pressures above 105 mmHg, but since then, targets have been progressively lower.
This J-curve has been reassessed in multiple studies since then. An interesting sub-analysis of the SPRINT trial demonstrated that although lower diastolic blood pressure is associated with an increased risk of cardiovascular events, further aggressive reduction of systolic blood pressure to the study target still leads to a reduction in cardiovascular events, even in individuals with lower diastolic blood pressure levels. Another large epidemiologic study demonstrated that while low diastolic blood pressure is associated with increased events, the effect is no longer present once adjusted for age, sex, risk factors, and systolic blood pressure levels. This study also demonstrated that the increased risk associated with low diastolic blood pressure was mostly explained by its association with older age and higher systolic blood pressure. Collectively, the evidence indicates that low diastolic BP does not cause worse outcomes; its association with cardiovascular events only represents reverse causation and confounding effects.
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