What question was this study supposed to answer?

To ascertain the protective effect of ventricular unloading by a microaxial flow pump (mAFP) in patients with severe coronary artery disease and LV dysfunction undergoing elective complex PCI. 

What did the study show?  

• 300 patients were randomized before elective or nonurgent complex PCI; 148 in the Impella arm and 152 in the standard care(SC). The study was carried out in 21 centers in the United Kingdom. 
• > 80% were Caucasian men with an average age of 73 years. 76 % had ACS. 42% had CCS 3 or 4 Angina and 46% were in NYHA Class III or IV heart failure. Mean EF was 27%, BCIS jeopardy scores averaged 8/12 with Syntax score at 38. Left Main PCI was performed in 72%, calcium modification in 81% and CTO PCI in 27% of cases.
• At 22 months, pairwise comparisons were 36.6% for mAFP vs 43% for SC with a WIN ratio of 0.85. All-cause death was 32.6% in patients with mAFP vs 23.4% with SC. CV death was 26.7% in patients with mAFP vs 14.5 % with SC. Major bleeding occurred in 10.8 % of patients with  mAFP vs 7.3% with SC. Vascular complications occurred in 16.9% of patients with mAFP vs 10.6% with SC. Spontaneous MI occurred in 12.4% of patients with SC vs 6.8% mAFP patients.

Conclusion

Elective left ventricular unloading with a mAFP or Impella device did not reduce the risk of major adverse clinical outcomes in complex high-risk patients (CHIP) undergoing PCI.