Very low BP tied to increased risk of CV events in high-risk patients
Lowering systolic blood pressure (SBP) to <120 mm Hg and diastolic blood pressure (DBP) to <70 mm Hg during treatment in high-risk patients was associated with an increased risk of cardiovascular (CV) events, except for stroke, according to pooled results from the ONTARGET* and TRANSCEND** trials.
“In high-risk patients, a target blood pressure of 120–130 mm Hg systolic and 70–80 mm Hg diastolic is associated with lowest rates of CV disease events,” observed the researchers led by Professor Michael Böhm of Universität des Saarlandes in Hamburg, Germany. “These data suggest that the lowest blood pressure possible is not necessarily the optimal target for high-risk patients.”
The two trials included a total of 30,937 high-risk patients (aged ≥55 years) with a history of CV disease or diabetes, who were predominantly hypertensive (70 percent). Angiotensin-converting-enzyme (ACE)-inhibitors tolerant patients (n=25,127) were randomized to oral telmisartan 80 mg/day (n=8,386), ramipril 10 mg/day (n=8,402), or both (n=8,334) in ONTARGET, whereas ACE-inhibitor intolerant patients (n=5,810) were randomized to oral telmisartan 80 mg/day (n=2,903) or placebo (n=2,907) in TRANSCEND. [Lancet 2017;doi:10.1016/S0140-6736(17)30754-7]
After a median 56-month follow-up, patients with a baseline SBP ≥140 mm Hg had a greater incidence of all outcomes, including the combined primary outcome (CV death, myocardial infarction [MI], stroke, and hospital admission for heart failure) and all-cause death, than those with a baseline SBP of 120 mm Hg to <140 mm Hg. Similarly, having a baseline DBP <70 mm Hg was associated with a higher risk for all outcomes except stroke compared with a DBP ≥70 mm Hg.
Böhm and colleagues also found that “the average SBP during treatment had a greater potential to predict outcomes than baseline SBP or the last value before an event.”
Among 4,052 patients who achieved a mean SBP <120 mm Hg during treatment, increased risks in the composite CV outcome (adjusted hazard ratio [HR], 1.14, 95 percent confidence interval [CI], 1.03–1.26), CV death (HR, 1.29, 95 percent CI, 1.12–1.49), and all deaths (HR, 1.28, 95 percent CI, 1.15–1.42) were observed compared with those with SBP 120–140 mm Hg during treatment (n=16,099), showing J-shaped curves for these outcomes. No significant difference was observed for risks of stroke, MI, and hospital admission for heart failure.
“[T]he lowest risk [occurred] at approximately [a mean achieved SBP of] 130 mm Hg,” said Böhm and co-authors, who observed that at 110–120 mm Hg, the risks of combined outcome, CV death, and all-cause death were increased except for stroke. “According to our analysis, in higher risk patients, achieving a[n] SBP less than 130 mm Hg but not lower than 120 mm Hg should be safe for most and result in improved outcomes.”
“The findings suggest that in some patients at low SBP on treatment, blood pressure medication might have to be reduced to avoid adverse outcomes because treat to target does not mean treat under target,” they added.
Similarly for a mean DBP <70 mm Hg during treatment (n=5,352), there were increased risks in the composite primary outcome (HR, 1.31, 95 percent CI, 1.20–1.42), MI (HR, 1.55, 95 percent CI, 1.33–1.80), all-cause death (HR, 1.16, 95 percent CI, 1.06–1.28), and hospital admission for heart failure (HR, 1.59, 95 percent CI, 1.36–186) compared with those with DBP of 70–80 mm Hg (n=14,305). A mean DBP during treatment of about 75 mm Hg (as well as at baseline) was associated with the lowest risk.
“[T]hese data indicate that achieved blood pressure values have diverse benefit for different outcomes and this probably differs according to baseline risk in hypertensive patients. Consequently, people with a particular risk for a specific outcome—eg, stroke, might benefit from lower blood pressure than those who are more prone to develop MI or CV death,” explained Böhm and co-authors.
“[T]he challenge, however, is how to predict who is most likely to develop each of these events.”