The impact of blood pressure targets on haemodynamics in patients with cardiogenic shock caused by infarction-related out-of-hospital cardiac arrest: a substudy of the BOX-trial.

AIMS: Noradrenaline is frequently used to increase mean arterial pressure (MAP) in patients with cardiogenic shock caused by infarction-related out-of-hospital cardiac arrest (OHCA-AMICS). This Blood pressure and Oxygenation-Targets after OHCA (BOX)-trial subanalysis investigates the impact of different noradrenaline-mediated MAP-targets on overall haemodynamics and outcomes in OHCA-AMICS patients.

METHODS AND

RESULTS

The BOX-trial compared randomized, double-blinded MAP-targets of 63 mmHg (low-target) and 77 mmHg (high-target) in comatose OHCA patients. For this subanalysis, patients meeting eligibility criteria for AMICS according to the ongoing NORshock trial were included (percutaneous coronary intervention, hypotension, signs of hypoperfusion, and <30 min to return of spontaneous circulation). Haemodynamic parameters assessed were cardiac index (CI) and pulmonary capillary wedge pressure (PCWP). Markers of tissue perfusion comprised mixed venous oxygen saturation (SvO2) and lactate. Clinical endpoints included 365-day mortality, renal replacement therapy (RRT), and neurological outcomes. Within the cohort of 258 patients (low-target n = 132, high-target n = 126), mean age was 63 (±11) years, 84% were male, and patient characteristics were well balanced between groups. The high-target group received significantly higher doses of noradrenaline. CI increased over time in both groups (low-target: 1.50→2.88; high-target: 1.77→2.92 L/min/m2). Despite 8-19% higher CIs during the first 24 h, the high-target group consistently exhibited higher PCWPs. SvO2 was higher in the high-target group. Lactate levels were comparable and, on average, normalized in both groups within 6 h. Mortality, need for RRT, and neurological outcomes did not differ significantly.

CONCLUSION

In OHCA-AMICS patients, higher noradrenaline-mediated MAP increased CI and SvO2 but did not enhance tissue perfusion or clinical outcomes, and were associated with higher left-sided filling pressures.