Objectives: To test the safety and efficacy of intravascular imaging and specifically optical coherence tomography (OCT) as a diagnostic tool for left main angioplasty and analyze the mid-term outcome accordingly.

Background: Clinical data and international guidelines recommend the use of intravascular imaging ultrasound (IVUS) to guide left main (LM) angioplasty. Despite early experience using OCT in this setting is encouraging, the evidence supporting its use is still limited.

Methods: ROCK II is a multicenter, investigatordriven, retrospective European study to compare the performance of IVUS and OCT versus angiography in patients undergoing distal-LM stenting. The primary study endpoint was target-lesion failure (TLF) including cardiac death, target-vessel myocardial infarction and target-lesion revascularization. We designed this study hypothesizing the superiority of intravascular imaging over angiographic guidance alone, and the non-inferiority of OCT versus IVUS.

Results: A total of 730 patients, 377 with intravascular-imaging guidance (162 OCT, 215 IVUS) and 353 with angiographic guidance, were analyzed. The one-year rate of TLF was 21.2% with angiography and 12.7% with intravascularimaging (p=0.039), with no difference between OCT and IVUS (p=0.26). Intravascular-imaging was predictor of freedom from TLF (HR 0.46; 95% CI 0.23-0.93: p=0.03). Propensity-score matching identified three groups of 100 patients each with no significant differences in baseline characteristics. The one-year rate of TLF was 16% in the angiographic, 7% in the OCT and 6% in the IVUS group, respectively (p=0.03 for IVUS or OCT vs. angiography). No between-group significant differences in the rate of individual components of TLF were found.

Conclusions: Intravascular imaging was superior to angiography for distal LM stenting, with no difference between OCT and IVUS.