Mortality in PCI Patients With Incomplete Revascularization

In a recent retrospective observational study published in JAMA Cardiology, patients that underwent percutaneous coronary interventions with incomplete revascularization were at higher risk of mortality if they had at least 90% stenosis in an incompletely revascularized vessel, incomplete revascularization in 2 or more vessels, or proximal left anterior descending artery incomplete revascularization.

Prior to this study “there were no findings about the relationship between incomplete revascularization severity and mortality”, according to the first author of the study, Dr. Edward L. Hannan, who is a Professor and outcomes researcher of cardiac surgery and angioplasty at the University of Albany School of Public Health.

The multicenter registry-based study included patients of all non-federal PCI hospitals in New York State. The study looked at 41,639 New York state residents who underwent PCI with multivessel coronary disease with >70% stenosis in 2 of the 3 major coronary vessels between January 1, 2010, and December 31, 2012. The study aimed to evaluate the effect of the degree of stenosis in the incomplete vessels, the number of incomplete vessels, and the location of the incomplete vessels on mortality. The median follow-up duration was 3.4 years.

Hannan and his colleagues report a statistically significant 4.5% increase in the rate of mortality among patients with 70-89% stenosis in the incompletely revascularized lesion, and a 9% increase in mortality among patients with >90% stenosis in the incomplete vessel, compared to patients with complete revascularization at 3 years. As the number of incompletely revascularized vessels increased, the risk of mortality increased. Patients with 1 incomplete vessel had an approximately 5% increased rate of mortality, while those with 2 or more incomplete vessels had a 12% increased rate of mortality at 3 years. The risk of mortality was significantly increased in those with 2 or more incomplete vessels compared to those with 1 incomplete vessel. Finally, patients with proximal LAD incomplete lesions had a 12% increase in the rate of mortality compared to those with complete revascularization. Interestingly, compared to those with complete revascularization, the rate of mortality was still 6% higher in patients without a proximal LAD incomplete lesion. Proximal LAD incomplete lesions were associated with a 30% relative increase in mortality compared to non-proximal LAD incomplete lesions.

The authors noted that a caveat of all observation studies include selection bias and that despite statistically adjusting for known patient characteristics, “an observational study cannot fully address causality, and the outcome differences identified in our study may still be related to differences in patients’ severity of illness.” The investigators did not have access to the cause of death. Nonetheless, Dr. Hannan comments that “Interventionalists should be wary of always performing incomplete revascularization and should consider complete revascularization or even CABG if complete revascularization is not possible” and adds that “these considerations should be intensified for high-risk incomplete revascularization patients”.

When asked to comment on the implications of these findings on his clinical practice, interventional cardiologist Dr. Robert Yeh, who is an Associate Professor of Medicine at Harvard Medical School and the Director of the Richard and Susan Smith Center for Outcomes Research in Cardiology at the Beth Israel Deaconess Medical Center, said “We should be looking to achieve optimal revascularization – there are times when this may mean that all significant lesions are revascularized but there are other times when using one’s discretion to not treat lesions based on unfavorable risk: benefit is still the better part of valor.” Though, Dr. Yeh agrees there have been several observational studies showing similar results of incomplete versus complete revascularization he said, “A simple explanation for this is that the definition of complete revascularization here included staged procedures performed within 60 days.  This provision effectively makes all patients who got staged procedures ‘immortal’ between the time of their index and staged procedures, since you have to survive, by definition, to get a staged procedure.  This is a common epidemiological bias known as immortal time bias.”

“There is too much potential bias and confounding for questions like these to trust anything other than randomized evidence.”, he added, “I certainly aim to revascularize vessels that are causing significant symptoms or any that are culprit lesions for myocardial infarction.  Those that are functionally significant and subtend important amounts of myocardium also qualify.  But revascularization for some the sake of ‘completeness’ doesn’t seem to be evidence-based.”