Concomitant coronary artery disease (CAD) is frequent in patients referred for transcatheter aortic valve replacement (TAVI) and there is evidence for a subsequent prognostic impairment. Percutaneous coronary intervention (PCI) is believed to improve prognosis in selected cases, which is why current guidelines recommend PCI to be considered in case of coronary artery diameter stenosis > 70% in proximal segments. Beyond those cases, selection is hampered by inherent shortcoming of the assessment of CAD severity by angiography alone as well as clinical and complex hemodynamic interactions between both pathologies. In patients with CAD alone, the FDA-cleared near-infrared spectroscopy and intravascular imaging (NIRS-IVUS) dual imaging catheter (Indfraredx, Inc., Bedford, USA) has proven the ability to reliably measure lipid plaque burden as well as to identify patients and plaques at increased risk for future adverse cardiovascular events. NIRS-IVUS imaging offers the unique possibility to improve angiographic CAD severity assessment in patients referred for TAVI, avoiding the influence of hemodynamic interactions and pathophysiological overlap between CAD and severe AS.
The IMPACTavi trial is designed as a prospective, non-randomized cohort study to investigate whether NIRS-IVUS-derived lesion characteristics will allow identification of patients likely to suffer adverse clinical events during clinical follow-up after TAVI. Patients with severe aortic stenosis will be qualified for enrollment if routine coronary angiography during diagnostic workup before TAVI shows evidence of coronary artery disease with at least one native vessel without prior stent implantation and at least one lesion requiring NIRS-IVUS imaging for clinical indications, and if at 30mm of total NIRS-IVUS pullback length in sufficient quality for offline analysis have been obtained. Clinical indication, technique and timing of PCI and TAVI will be at the discretion of the interdisciplinary heart-team. The primary and secondary endpoints will be assessed during clinical follow-up out to 24 months. Findings from NIRS-IVUS imaging will be analyzed on a patient- and lesion-level, in order to evaluate correlations of high- vs. low-risk lesion characteristics to the incidence of patient- and lesion-level MACE.