International Circulation: How do evaluate the J-curve of blood pressure? Is there a J-curve for both systolic and diastolic blood pressures and which one is more important?
国际循环：如何评价血压的J-型曲线？SBP和DBP是否均存在J型曲线，哪一个更重要？

Alberto Zanchetti: The J-curve surely exists because at zero blood pressure you are dead. So the question is， if you go down to normal blood pressure of 110 or 115， is there an increased risk? I think this is very difficult to prove， and even more difficult to prove in different patients. Most of the studies that have shown there is a J-curve or have disputed that there is a J-curve， are all post hoc analyses. In these analyses randomization is lost， and there is no trial in which a group of patients is randomized at 110 and another group to， say， 130. This will be the only way to show whether there is a J-shape curve. In general terms， in principle， if you look at groups of uncomplicated patients they are at no risk of a J-curve until you bring them to a normal pressure. Maybe in the case of the patient with severe stenosis of the coronary or carotid artery this may occur but we don’t have the proof. I think the solution must be left to the clinician. If the clinician is prudent enough to lower blood pressure progressively， while constantly controlling the well being of the patient， then the clinician can easily realize when the patient may be disturbed by excessive lowering of blood pressure. I think it is more a medical problem rather than an epidemiological one.