CHIP‑BCIS3: LV Unloading Not Beneficial During PCI in Patients With Severe LV Dysfunction

The CHIP‑BCIS3 trial, presented at ACC.26 and simultaneously published in the New England Journal of Medicine, shows that elective LV unloading with a microaxial flow pump did not improve outcomes—and may have increased harm—among patients with severe left ventricular (LV) dysfunction undergoing complex PCI. 

In this UK‑based, open‑label study, 300 patients with LVEF ≤ 35% and extensive coronary disease were randomized to elective unloading versus standard‑care PCI, and 299 actually underwent the procedure.

At a median follow‑up of 22 months, the primary hierarchical endpoint—a composite of all‑cause death, disabling stroke, spontaneous MI, cardiovascular hospitalization, and periprocedural myocardial injury—was no better with LV unloading, with a win ratio of 0.85 (p = 0.30) favoring the control group in pairwise comparisons. 

The microaxial flow pump arm had a higher rate of all‑cause death (32.6% vs 23.4%) and cardiovascular death (26.7% vs 14.5%), and more periprocedural myocardial injury than the standard‑care group, without a reduction in bleeding or vascular complications.

The investigators describe the results as “surprising,” since the theoretical rationale for LV unloading is to protect the heart during high‑risk PCI; instead, patients assigned to unloading appeared to sustain more LV damage.

The accompanying editorial stresses that CHIP‑BCIS3 underscores the need for a more selective, indication‑driven use of mechanical circulatory support in high‑risk PCI, especially in patients without clear hemodynamic instability. 

For practicing interventionalists, these data argue against routine prophylactic LV unloading in complex PCI for severe LV dysfunction and reinforce that physiological benefit does not automatically translate into clinical benefit in this population.