We evaluated the impact of thrombus burden as measured by Optical Coherence Tomography on the occurrence of periprocedural myocardial infarction (type IVa MI) in pts undergoing percutaneous coronary intervention (PCI) in non ST elevation acute coronary syndrome (NSTE-ACS).

Prospective multicenter study including pts treated for NSTE-ACS (<72h) undergoing PCI of the infarct related artery (IRA). OCT was performed before and after PCI. Thrombus burden was measured quantitatively by planimetry, and semi-quantitatively by the OCT thrombus score. Primary endpoint was the rate of type IVa MI. Secondary endpoints were the relationship between OCT characteristics of the IRA and volume of thrombus, correlation between thrombus volume measured pre-PCI and functional outcome of the angioplasty evaluated by fractional flow reserve (FFR) post-procedure.

Hundred and twenty pts aged 60.8±11 years were included. Thrombus was more frequently present on OCT [83 (69%)] than on angiography [54 (45%), P<0.0001]. Type IVa MI occurred in 48 pts (40%). The occurrence of type IVa MI was not related to presence of thrombus on OCT (33 (40%) with vs. 15 without (41%) P=0.93). Thrombus volume evaluated by planimetry or semi-quantitavely did not predict type IVa MI. There was a strong association between presence of thrombus pre-PCI and presence of tissue prolapse post-PCI. The volume of thrombus was significantly correlated with the volume of tissue prolapse (P=0.03 and P=0.01). The presence of thrombus and volume of thrombus as measured pre-PCI did not affect post-PCI FFR (0.94±0.04 vs. 0.93±0.04, for presence vs. absence of thrombus, P=0.51).

OCT allows better visualization of thrombus than angiography in NSTE-ACS. In pts receiving antithrombotic therapy, neither the presence nor the volume of thrombus impacts the occurrence of a periprocedural myocardial infarction. Thrombus burden does not influence the functional outcome of angioplasty as measured by FFR.