Does excessive lowering of diastolic blood pressure increase the risk of coronary events in patients with coronary artery disease or essential hypertension?
While a J-curve relationship exists where very low diastolic blood pressure may increase coronary risk in CAD patients, this should not deter physicians from pursuing recommended blood pressure targets.
The topic of the J-curve relationship between blood pressure and coronary artery disease (CAD) has been the subject of much controversy for the past decades. An inverse relationship between diastolic pressure and adverse cardiac ischemic events (i.e., the lower the diastolic pressure the greater the risk of coronary heart disease and adverse outcomes) has been observed in numerous studies. This effect is even more pronounced in patients with underlying CAD. Indeed, a J-shaped relationship between diastolic pressure and coronary events was documented in treated patients with CAD in most large trials that scrutinized this relationship. In contrast to any other vascular bed, the coronary circulation receives its perfusion mostly during diastole; hence, an excessive decrease in diastolic pressure can significantly hamper perfusion. This adverse effect of too low a diastolic pressure on coronary heart disease leaves the practicing physician with the disturbing possibility that, in patients at risk, lowering blood pressure to levels that prevent stroke or renal disease might actually precipitate myocardial ischemia. However, these concerns should not deter physicians from pursuing a more aggressive control of hypertension, because currently blood pressure is brought to recommended target levels in only approximately one-third of patients.
“the diastolic blood pressure J-curve may have little to do with diastolic blood pressure itself and more to do with other parameters like vascular stiffness or vascular calcification that are the true culprits in the observation between increased risk and low diastolic blood pressure”
Messerli et al. (Sun,) studied this question.