Orbital Atherectomy for the Treatment of Long (≥25-40 mm) Severely Calcified Coronary Lesions: ORBIT II Sub-Analysis.

Background: Orbital atherectomy (OA) is an effective method of lesion preparation of severely calcified vessels prior to stent deployment. Long calcified lesions may lead to higher risk of post-procedural complications, yet the optimal treatment strategy has not been established. In this study we sought to determine the safety and efficacy of OA in patients with long (≥25-40 mm) calcified target lesions.

Methods: ORBIT II was a single-arm trial that enrolled 443 patients at 49 U.S. sites. De novo, severely calcified coronary lesions were treated with OA prior to stenting. Patients treated with the OA device were stratified into two groups according to target lesion length as visually estimated by the investigator: those with short (<25 mm; N = 314) vs. long (≥25-40 mm; N = 118) lesions. Lesions >40 mm were excluded per protocol. The primary endpoint was the 3-year major adverse cardiac event (MACE) rate, defined as a composite of cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR).

Results: The 3-year MACE rates in patients with short (<25 mm) vs. long (≥25-40 mm) lesions were 21.1% vs. 29.9% respectively (p = 0.055). The rate of cardiac death (6.5% vs. 7.8%, p = 0.592) and TVR (8.5% vs. 13.7%, p = 0.153) did not significantly differ. The rate of MI (CK-MB > 3× ULN) at 3 years was significantly higher in patients with long (≥25-40 mm) lesions (9.0% vs. 17.0%, p = 0.024), with the majority occurring in-hospital (7.0% vs. 13.6%, p = 0.037).

Conclusions: Patients with long (≥25-40 mm) calcified target lesions had similar outcomes in terms of MACE at 3 years despite higher rates of MI, which mostly occurred in-hospital. Using the more contemporary SCAI definition of MI, there was no significant difference in rates of MI between the short (<25 mm) and long (≥25-40 mm) groups. Further studies are warranted to determine how OA compares to focal force balloon angioplasty, rotational atherectomy and other novel treatment options for long severely calcified lesions.

Summary For Annotated Table Of Contents: Percutaneous coronary intervention of long calcified lesions is inherently more complex and higher risk and may require more intensive lesion preparation. This sub-analysis of ORBIT II revealed that orbital atherectomy treatment of longer (≥25-40 mm) lesions was associated with a higher rate of MACE at 30 days, but not at 3 years. This difference, however, was driven primarily by a higher in-hospital non-Q-wave MI rate; using the more contemporary SCAI definition of MI, there was no significant difference in rates of MI between the short (<25 mm) and long (≥25-40 mm) groups.