2-Year Results of Abbott's ABSORB Trial Published

March 12, 2009—Abbott Vascular (Santa Clara, CA) announced that a comprehensive analysis of the ABSORB trial by Patrick W. Serruys, MD, et al was published in The Lancet (2009;373:897-910). According to the analysis, the ABSORB clinical trial demonstrated that Abbott's bioabsorbable drug-eluting stent, which is currently in development, successfully treated coronary artery disease and was absorbed into the walls of treated arteries within 2 years. The 2-year data also demonstrated that after the bioabsorbable device was absorbed, the treated blood vessels appeared to move and function similarly to unstented arteries. Preliminary findings from the 30-patient ABSORB trial were presented at the 2008 Transcatheter Cardiovascular Therapeutics annual meeting in Washington, DC.

According to Abbott, the ABSORB trial is a prospective, nonrandomized, two-phase study designed to enroll approximately 110 patients in Australia, Belgium, Denmark, France, the Netherlands, New Zealand, Poland, and Switzerland. Key endpoints of the study include assessments of safety—major adverse cardiac events (MACE) and stent thrombosis rates—at 30 days; 6, 9, and 18 months; and 1 and 2 years, with additional annual clinical follow-up for up to 5 years. There will also be an assessment of the acute performance of the bioabsorbable drug-eluting stent, which includes successful deployment. Other key endpoints of the study include imaging assessments by angiography, intravascular ultrasound, optical coherence tomography, and other state-of-the-art invasive and noninvasive imaging modalities at 6 and 18 months, and at 1 or 2 years. Abbott will begin enrolling patients in the second phase of its international ABSORB clinical trial in the first half of 2009.

As reported in The Lancet, the first phase of the ABSORB trial demonstrated the following key results:

• A 0% rate of stent thrombosis for all patients to 2 years of follow-up.
• No new MACE between 6 months and 2 years. At 2 years, the bioabsorbable device demonstrated a MACE rate of 3.6% (one patient). MACE is defined as any event that resulted in target lesion revascularization, myocardial infarction, or cardiac death.
• Bioabsorption of the stent at 2 years after implantation, as confirmed by an assessment of the stent struts using optical coherence tomography.
• Restoration of vasomotion was observed at 2 years with the drug acetylcholine used in nine patients showing vasodilation in the previously stented area, and the drug methergin used in seven patients showing vasoconstriction in the previously stented area.
• Reduction in plaque area in treated arteries corresponding to an increase in blood flow between 6 months and 2 years, as confirmed by intravascular ultrasound and virtual histology.

On March 24, Abbott Vascular announced the initiation of the next phase of the ABSORB trial, which will enroll approximately 80 patients at 10 centers in Europe, Australia, and New Zealand, and will incorporate device enhancements designed to improve deliverability and vessel support.