HOW LOW SHOULD WE GO TREATING HYPERTENSIVE PATIENTS WITH CAD?
Authors: Maria Dorobanțu
In the setting of hypertension atherosclerosis process becomes accelerate and sustained elevated BP levels can destabilize vascular lesions and lead to acute coronary events, making coronary heart disease the most common outcome of hypertension. Optimal BP control can reduce the cardiovascular risk attributed to hypertension but currently the optimal BP target in this setting remains controversial. Thus, the hypertensive patient with CAD remains a treatment challenge in which a fine balance on the edge must be maintained between lowering BP, reducing ischemia, and preventing cardiovascular events.
Both 2007 ESH/ESC and AHA Guidelines recommends to lower BP below 130/80mmHg in high risk patients such as CAD patients, but this linear theory “lower is better” has been challenged for nearly 3 last decades, especially for DBP. In contrast to any other vascular bed, the coronary circulation receives its perfusion mostly during diastole. An excessive decrease in diastolic pressure can significantly impair perfusion. In patients at risk, lowering blood pressure to levels that prevent stroke or renal disease might actually precipitate myocardial ischemia because this adverse effect of too low a diastolic pressure on coronary heart disease. This “J-curve phenomenon”, that has been under academic debate whether or not it truly exists, implies to a prudent approach in patients with concomitant CAD in which DBP should not be lowered to less than 70mmHg. More, studies such INVEST, VALUS, ONTARGET, TNT, PROVE-IT TIMI 22, have stress out a j-shaped relationship between achieved SBP levels and CV events leading to the conclusion that in patients with CAD a BP below 110-120/60-70 portends an increased risk of future CV events (except stroke).
Recently, in the light of these evidences, there is less enthusiasm for aggressive BP lowering, especially in CAD patients and the recommendation of previous guidelines to aim at a lower goal SBP (<130mmHg) in patients at very high cardiovascular risk (previous cardiovascular events) may be wise, but it is not consistently supported by trial evidence. As a result in 2009, ESH-ESC task force updated the recommendations for hypertension management acknowledging that in high-risk hypertensive patients, even intense cardiovascular drug therapy, though beneficial, is nonetheless unable to lower total cardiovascular risk below the high-risk threshold.
Anyhow, there is no consensus regarding the minimum safe level of SBP/DBP in hypertensive patients with CAD but BP should be lowered slowly by clinical judgment. Maybe the 2013 ESH-ESC guideline on hypertension management will offer us a new BP target for high-risk hypertensive patients.