The goal of hypertension treatment is to reduce cardiovascular diseases and unnecessary deaths. In lowering blood pressure, there is a concern that excessive lowering of blood pressure especially diastolic blood pressure (DBP) may impair coronary perfusion and increase the incidence of coronary events, the so called J-shaped relationship. The topic of the J-curve relationship has been the subject of much controversy for the past decades.
The real question was not whether there was a J-curve, obviously there had to be, because a BP of 0 encompasses a 100% mortality-the question was whether such a J-curve did occur within a “physiologic” range of BP. The only way to correctly investigate the J-curve phenomenon requires comparison of various BP targets. So far, only the HOT (Hypertension Optimal Treatment)1 study approached the issue in this way, but this trial was designed at a time when BP used to be reduced less aggressively; furthermore, HOT was conducted in hypertensive patients at low risk (~1% cardiovascular events per year).
Due to lack of direct evidence on the J-curve, recourse is being made to an indirect approach : incident outcomes in randomized trials both in hypertensive and non-hypertensive populations are plotted against achieved BP, independently of the randomized group, and the existence of a J-shaped relationship is explored.
On the whole, the existence of a J-shaped curve has been investigated for both systolic blood pressure (SBP) and DBP, although more often for DBP. Some of the analyses have concluded that no J-curve exists1-3, while others have concluded in favour of its existence4-8. Interestingly, some trial found J-curve in both actively treated and placebo patients4 while some found J-curve only in placebo treated patients9.
The data recently published8 are derived from a trial of lipid lowering [Treating to New Target (TNT)] rather than of antihypertensive treatment. In this analysis the investigators showed a J-shaped curve relationship both for SBP and DBP despite no substantial change in antihypertensive therapy for hypertensive patients (about 54% of the population), this may be taken to support the conclusions of the INDANA meta-analysis4 and SystEur5 that the J-curve, if it exists, may not be the result of antihypertensive therapy
The mostly desired question to be answer is what level SBP/DBP can be lowered to increase the overall benefit of the hypertensive patient without causing endangering hypoperfusion. Unfortunately, in the absence of correctly designed trials, all data that we have are still open to different and even contrasting interpretations. For the time being, it appears wise and safe to lower SBP/DBP to values within the range 130-139/80-85 mmHg, and possibly close to lower values in this range10
The goal of hypertension treatment is to reduce cardiovascular diseases and unnecessary deaths. In lowering blood pressure, there is a concern that excessive lowering of blood pressure especially diastolic blood pressure (DBP) may impair coronary perfusion and increase the incidence of coronary events, the so called J-shaped relationship. The topic of the J-curve relationship has been the subject of much controversy for the past decades.
The real question was not whether there was a J-curve, obviously there had to be, because a BP of 0 encompasses a 100% mortality-the question was whether such a J-curve did occur within a “physiologic” range of BP. The only way to correctly investigate the J-curve phenomenon requires comparison of various BP targets. So far, only the HOT (Hypertension Optimal Treatment)1 study approached the issue in this way, but this trial was designed at a time when BP used to be reduced less aggressively; furthermore, HOT was conducted in hypertensive patients at low risk (~1% cardiovascular events per year).
Due to lack of direct evidence on the J-curve, recourse is being made to an indirect approach : incident outcomes in randomized trials both in hypertensive and non-hypertensive populations are plotted against achieved BP, independently of the randomized group, and the existence of a J-shaped relationship is explored.
On the whole, the existence of a J-shaped curve has been investigated for both systolic blood pressure (SBP) and DBP, although more often for DBP. Some of the analyses have concluded that no J-curve exists1-3, while others have concluded in favour of its existence4-8. Interestingly, some trial found J-curve in both actively treated and placebo patients4 while some found J-curve only in placebo treated patients9.
The data recently published8 are derived from a trial of lipid lowering [Treating to New Target (TNT)] rather than of antihypertensive treatment. In this analysis the investigators showed a J-shaped curve relationship both for SBP and DBP despite no substantial change in antihypertensive therapy for hypertensive patients (about 54% of the population), this may be taken to support the conclusions of the INDANA meta-analysis4 and SystEur5 that the J-curve, if it exists, may not be the result of antihypertensive therapy
The mostly desired question to be answer is what level SBP/DBP can be lowered to increase the overall benefit of the hypertensive patient without causing endangering hypoperfusion. Unfortunately, in the absence of correctly designed trials, all data that we have are still open to different and even contrasting interpretations. For the time being, it appears wise and safe to lower SBP/DBP to values within the range 130-139/80-85 mmHg, and possibly close to lower values in this range10
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