Blood Pressure Target to Prevent Cardiovascular Events
Abstract & Commentary
By Michael H. Crawford, MD, Editor
Sources: Mancia G, et al. Blood pressure targets recommended by guidelines and incidence of cardiovascular and renal events in the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET). Circulation 2011;124:1727-1736. Chalmers J. Is a blood pressure target of 130/80 mm Hg still appropriate for high risk patients? Circulation 2011;124:1700-1702.
Guidelines recommend aggressive systolic blood pressure (BP) goals (< 130/80 mmHg) in patients at high risk for cardiovascular (CV) events. However, there are few data to support this recommendation. Thus, investigators from the Ongoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) used this database to determine the outcomes of achieving a BP < 140/90 vs < 130/80. This trial compared telmisartan to ramipril to both. Since the outcomes were not different, this analysis combined all three groups and adjusted for baseline differences. The primary endpoint was CV mortality, myocardial infarction (MI), stroke, or heart failure hospitalization. Secondary endpoints included renal function parameters. They identified four groups based on the percentage of visit blood pressures (BPs) at the two targets (< 25%, 25-49%, 50-74%, and ≥ 75%). All patients had a minimum of seven visits. As the percent of visits with BP control to either target increased, there was a progressive decrease in stroke and albuminuria. However, no difference in MI or heart failure hospitalization was demonstrated. Also, the primary endpoint of total CV events was reduced by increasing the frequency of BP control to the < 140/90 target, but not the 130/80 target. The authors concluded that achieving the guideline target of < 130/80 reduced stroke and improved renal protection, but did not prevent cardiac events. Achieving the < 140/90 target did protect the patients from cardiac events.
Commentary
These results are consistent with prior studies. INVEST showed that achieving the lower target BP in diabetics was not associated with fewer CV events. Also, in ACCORD-BP, which studied hypertensive diabetics, achieving a lower target (mean systolic of 119) reduced stroke but not CV mortality or MI. Although the mechanisms for these observations are not revealed in these studies, it is reasoned that the coronary circulation requires a higher BP as compared to the brain and kidney. Thus, lowering diastolic pressure excessively in those with coronary disease would be expected to result in myocardial ischemia.
With regard to lowering BP, there is clearly a J-shaped mortality curve because organ function requires a certain level of perfusion. As the editorial with this article points out, it is unclear whether the point of increased risk is within the usual BPs achieved in clinical practice and whether it is different in patients with various disease. This study, like previous ones, does not show a definite J curve, but rather that there is no further benefit after lowering BP to < 140/90 in cardiac endpoints. However, those at risk for stroke or renal disease may benefit from a target of < 130/80. The authors suggest that in Asians, who have a higher risk of stroke than Caucasians, the lower target may be more appropriate. However, their study does not directly address this issue.
The major weakness of this study is that it is a non-randomized post hoc observational assessment. Any conclusions are hypothesis generating and a randomized outcome study will need to be done to definitively answer the question of BP targets in hypertensive patients. However, at this time, there are few data to support the more aggressive targets. On the other hand, there seems to be little harm in achieving BPs lower than 130/80. Most studies rarely achieve BPs lower than 110/70, so this seems like a safe lower limit for most patients. The real problem in hypertension is getting patients to the accepted level of < 140/90. Most surveys show that only about 50-60% of treated patients achieve this conservative target. At this time, we should be focusing on getting most of our patients to < 140/90 and not worry about lowering their BP too much as long as it is > 110/70. Of course there are going to be exceptions to this. Older patients with diffuse atherosclerosis will tolerate a wider pulse pressure; so a target of < 150/90 may be appropriate with diastolics to 60 acceptable.
Guidelines recommend aggressive systolic blood pressure (BP) goals (< 130/80 mmHg) in patients at high risk for cardiovascular (CV) events.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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