The significance of the J-curve in hypertension and coronary artery diseases

The J-curve effect describes an inverse relation between low blood pressure (BP) and cardiovascular complications. This effect is more pronounced in patients with preexisting coronary artery disease (CAD), hypertension or left ventricular hypertrophy (LVH). The recent large clinical outcomes trials have observed a J-curve effect between a diastolic BP of 70-80 mmHg as well as a systolic BP <130 mmHg. The J-curve phenomenon does not appear in stroke or renal disease. This is because the coronary arteries are perfused during diastole, but the cerebral and renal perfusion mainly occurs in systole. Therefore, caution should be taken to maintain the diastolic blood pressure (DBP) at minimum of 70 mmHg and possibly to maintain the DBP between 80-85 mmHg in patients with severe LVH, CAD or vascular diseases. BP control in high-risk elderly patients should be carefully done as undergoing aggressive therapy to lower the systolic blood pressure below 140 mmHg can cause cardiovascular complications due to the severely reduced DBP and increased pulse pressure.