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Blood Pressure Targets in Comatose Survivors of Cardiac Arrest
Quick Takes
- There was no significant difference in the percentage of patients who died or were discharged from the hospital with a poor neurologic outcome within 90 days with a mean arterial blood pressure target of 63 mm Hg as compared with 77 mm Hg.
- The current study also did not suggest a benefit of a higher blood pressure target in the subgroup of patients with known hypertension.
Study Questions:
What are the optimal blood pressure targets for the treatment of comatose survivors of out-of-hospital cardiac arrest who are receiving intensive care?
Methods:
The BOX (Blood Pressure and OXygenation Targets After OHCA) trial investigators evaluated a mean arterial blood pressure target of 63 mm Hg as compared with 77 mm Hg in comatose adults who had been resuscitated after an out-of-hospital cardiac arrest of presumed cardiac cause in this double-blind, randomized trial with a 2-by-2 factorial design. Patients were also assigned to one of two oxygen targets (reported separately). The primary outcome was a composite of death from any cause or hospital discharge with a Cerebral Performance Category (CPC) of 3 or 4 within 90 days (range, 0-5, with higher categories indicating more severe disability; a category of 3 or 4 indicates severe disability or coma). Secondary outcomes included neuron-specific enolase levels at 48 hours, death from any cause, scores on the Montreal Cognitive Assessment (range, 0-30, with higher scores indicating better cognitive ability) and the modified Rankin scale (range, 0-6, with higher scores indicating greater disability) at 3 months, and the CPC at 3 months. The primary outcome and the secondary outcomes relating to death from any cause and receipt of renal replacement therapy were adjusted for site in a proportional-hazards model.
Results:
A total of 789 patients were included in the analysis (393 in the high-target group and 396 in the low-target group). A primary outcome event occurred in 133 patients (34%) in the high-target group and in 127 patients (32%) in the low-target group (hazard ratio, 1.08; 95% confidence interval [CI], 0.84-1.37; p = 0.56). At 90 days, 122 patients (31%) in the high-target group and 114 patients (29%) in the low-target group had died (hazard ratio, 1.13; 95% CI, 0.88-1.46). The median CPC was 1 (interquartile range, 1-5) in both the high-target group and the low-target group; the corresponding median modified Rankin scale scores were 1 (interquartile range, 0-6) and 1 (interquartile range, 0-6), and the corresponding median Montreal Cognitive Assessment scores were 27 (interquartile range, 24-29) and 26 (interquartile range, 24-29). The median neuron-specific enolase level at 48 hours was also similar in the two groups. The percentages of patients with adverse events did not differ significantly between the groups.
Conclusions:
The authors concluded that targeting a mean arterial blood pressure of 77 mm Hg or 63 mm Hg in patients who had been resuscitated from cardiac arrest did not result in significantly different percentages of patients dying or having severe disability or coma.
Perspective:
This double-blind, randomized trial comparing a mean arterial blood pressure of 77 mm Hg versus 63 mm Hg found no significant difference in the percentage of patients who died or were discharged from the hospital with a poor neurologic outcome (CPC of 3 or 4) within 90 days. Furthermore, the results were consistent in the prespecified subgroups. Of note, the current study also did not suggest a benefit of a higher blood pressure target in the subgroup of patients with known hypertension.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Cardiovascular Care Team, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Hypertension
Keywords: Acute Coronary Syndrome, Blood Pressure, Cognition, Coma, Critical Care, Heart Arrest, Hypertension, Mental Status and Dementia Tests, Out-of-Hospital Cardiac Arrest, Oxygen, Patient Discharge, Renal Replacement Therapy, Secondary Prevention, Survivors
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