Blood Pressure Levels and Stroke: J-curve Phenomenon?

The blood pressure J-curve discussion has been ongoing for more than 30 years, yet there are still questions in need of definitive answers. On one hand, existing antihypertensive therapy studies provide strong evidence for J-curve-shaped relationships between both diastolic and systolic blood pressure and primary outcomes in the general hypertensive patient population, as well as in high-risk populations, including subjects with coronary artery disease, diabetes mellitus, left ventricular hypertrophy, and the elderly. On the other hand, we have very limited data on the relationship between systolic and diastolic blood pressure and stroke prevention. Moreover, it seems that this outcome is more a case of "the lower the better." Further large, well-designed studies are necessary in order to clarify this issue, especially as existing available studies are observational, and randomized trials either did not have or lost statistical power and were thus inconclusive.