Investigating the Utility of Remote Index of Microvascular Resistance in Patients With Chronic Total Occlusion

This is prospective cohort study in subjects with a planned percutaneous coronary intervention (PCI) of their chronic total occlusion (CTO). The study will enroll subjects who have been scheduled for a clinically-indicated cardiac catheterization, and will evaluate coronary microvascular function in all subjects meeting inclusion criteria with a coronary flow wire. Evaluation of coronary microvascular function may be performed using indirect methods, however the rationale behind the present study is to directly measure microvascular function using direct coronary flow measurements, since the subjects in the study are to undergo a clinically-indicated cardiac catheterization. The overall purpose of the study is to define the presence and severity of coronary microvascular dysfunction subjects with CTO. The study is designed to enroll 50 subjects with CTO in the span of 3 years. There will be a 6-month assessment of the outcomes of death and cardiovascular death. As the study includes FDA approved tests, there will be no safety endpoint per se, however there will be a mechanism for monitoring adverse events as will be described in detail.