Among patients with severe left ventricular (LV) dysfunction and severe coronary heart disease undergoing complex PCI, elective LV unloading with a microaxial flow pump did not reduce the risk of major adverse clinical outcomes and carried a greater risk of all-cause and cardiovascular mortality, according to results of the CHIP-BCIS3 trial presented during a Late-Breaking Clinical Trial session at ACC.26 in New Orleans and simultaneously published in NEJM.

Conducted at 21 sites in the UK, the prospective, open-label trial randomized 300 patients with severe LV dysfunction (LVEF ≤35%) and extensive coronary disease to either a strategy of elective unloading with a microaxial flow pump (n=148) or standard care (n=152) during a planned complex PCI. PCI was performed in 299 patients; one patient in the standard care group died before the procedure.

The mean age of patients was 73 years and 17% were women. The median LVEF was 27%; median core laboratory-adjudicated British Cardiovascular Intervention Society Jeopardy Score was 12, and median SYNTAX score was 38.

Results at a median follow-up of 22 months showed that 111/140 (79.3%) patients in the microaxial flow pump group vs. 100/139 (73.6%) patients in the standard care group experienced the primary endpoint, a hierarchical composite of all-cause death, disabling stroke, spontaneous myocardial infarction (MI), cardiovascular hospitalization and periprocedural myocardial injury, analyzed using a win ratio.

Of 22,496 pairwise comparisons, 36.6% favored the microaxial flow pump and 43.0% favored standard care, with a win ratio of 0.85 (p=0.30).

In terms of secondary outcomes, death from any cause occurred in 47/148 (32.6%) patients in the microaxial flow pump group vs. 33/152 (23.4%) in the standard care group (hazard ratio, 1,54) and cardiovascular death in 36/148 (26.7%) vs. 20/152 (14.5%) patients, respectively. There were no between-group differences in risk of bleeding or vascular complications. However, 82/133 (61.7%) patients in the microaxial flow pump group experienced periprocedural myocardial injury vs. 62/124 (50.0%) in the control group.

The results were "surprising because the whole premise of LV unloading was that it protects the heart," said Divaka Perera, MD, first author of the study. "But we found that patients assigned to LV unloading had more damage to the [LV] than those assigned to standard care."

"Our findings strongly suggest that we shouldn't be using this device routinely without more evidence of benefit," he added.

In an accompanying editorial comment, Brahmajee K. Nallamothu, MD, FACC, and Brett L. Wanamaker, MD, FACC, stress the important influence of trials like CHIP-BCIS3 in the cath lab, where "the margin between a good outcome and a catastrophic one is narrow, and the instinct to add protection with mechanical circulatory support can be powerful" in PCI procedures.

Noting the major physiological effects such support can have on patients, they write that, "the CHIP-BCIS3 investigators provide sufficient data to encourage a more selective approach to the use of mechanical circulatory support in high-risk PCI, particularly in the absence of clear hemodynamic instability."

Clinical Topics: Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: ACC Annual Scientific Session, ACC26, Angiography, Percutaneous Coronary Intervention, New Orleans, Ventricular Dysfunction, Left, Coronary Disease, Myocardial Infarction, Prospective Studies, Hemodynamics, Stroke