Key Points
- Elective use of a microaxial flow pump during high-risk PCI did not reduce major adverse clinical outcomes compared with standard care (win ratio 0.85; 95% CI, 0.63–1.15; p=0.30).
- There was a numerical increase in mortality, including higher cardiovascular death with the device strategy (HR 1.91; 95% CI, 1.11–3.30).
- Despite theoretical hemodynamic benefits, no improvement in revascularization completeness or ischemic outcomes was observed, with similar or worse periprocedural myocardial injury.
Complex PCI in patients with severe left ventricular dysfunction remains at high risk, and mechanical circulatory support has been increasingly adopted despite limited randomized evidence. The CHIP-BCIS3 trial (NCT5003817), presented at ACC.26 and simultaneously published in the New England Journal of Medicine, evaluated whether elective left ventricular unloading with a microaxial flow pump improves outcomes in this population.
This prospective, multicenter, randomized trial enrolled 300 patients with severe LV dysfunction (median LVEF ~27%) and extensive coronary artery disease undergoing complex PCI. Patients were randomized 1:1 to microaxial flow pump support (n=148) versus standard care without planned mechanical support (n=152). The primary endpoint was a hierarchical composite of death, disabling stroke, spontaneous MI, cardiovascular hospitalization, or periprocedural myocardial injury, analyzed using a win-ratio approach.
At a median follow-up of 22 months, the primary outcome showed no benefit with the microaxial flow pump strategy: 36.6% of pairwise comparisons favored the device versus 43.0% favoring standard care (win ratio 0.85; 95% CI, 0.63–1.15; p=0.30), corresponding to an absolute difference of −6.4 percentage points. Sensitivity analyses were consistent, with no difference in time-to-first-event composite outcomes (HR 1.06; 95% CI, 0.75–1.49 when excluding periprocedural MI).
Notably, mortality signals favored standard care. Death from any cause occurred in 32.6% of patients in the microaxial flow pump group versus 23.4% in the standard-care group (HR 1.54; 95% CI, 0.99–2.41). Cardiovascular death was significantly higher with device use (26.7% vs. 14.5%; HR 1.91; 95% CI, 1.11–3.30). There were no significant differences in other ischemic outcomes: spontaneous MI (HR 0.64; 95% CI, 0.28–1.47), cardiovascular hospitalization (HR 1.20; 95% CI, 0.72–1.98), or disabling stroke (HR 0.53; 95% CI, 0.13–2.11). Periprocedural myocardial injury was numerically higher with the device (61.7% vs. 50.0%; risk ratio 1.23; 95% CI, 0.99–1.54).
Importantly, procedural goals were not improved by mechanical support. Completeness of revascularization was similar between groups (median coronary revascularization index ~67%), undermining the hypothesis that hemodynamic support enables more complete PCI. Safety outcomes showed no statistically significant differences in major bleeding (10.8% vs. 7.3%; RR 1.48; 95% CI, 0.71–3.09) or major vascular complications. Overall, CHIP-BCIS3 provides the first randomized evidence directly comparing elective microaxial flow pump use versus no planned support in high-risk PCI—and does not support routine upfront use of these devices in stable patients with severe LV dysfunction. Dr. Divaka Perera, the study’s senior author, stated: “Using a microaxial flow pump upfront and electively does not appear to reduce the rates of major adverse events, and this signal of excess deaths, in particularly, cardiovascular deaths requires further investigation.”