LAUSR

We read with great interest the report by Desai and colleagues on the utilization of intravascular ultrasound (IVUS) in patients treated with atherectomy in the United States from 2012 to 2014 during percutaneous coronary intervention (PCI). Although data were available for IVUS use, this was essentially binary information. The available data did not provide insight on whether IVUS was used either before PCI, after PCI, both, or as a response for further assessment after a procedural complication. A selection bias affecting a decision of an operator to use IVUS may have also been influenced by increased procedural complexity not inherent by baseline characteristics alone. These confounding factors severely limit what can be gleaned from this analysis with regard to differences in clinical outcomes. Therefore, the higher odds of a cardiac complication in the data described that was reported to be associated with IVUS use may actually have occurred before the use of IVUS. The associated use of IVUS with iatrogenic complications is likely documentation of a reaction to a complication with the use of IVUS rather than identification of any causality. Additionally, the increased hospitalization charges in the IVUS cohort was beyond the cost of an IVUS catheter and more likely related to the increased complications in this group rather than use of IVUS itself. This study provides important insight into practice patterns, however, and the underutilization of IVUS in severely calcified lesions. Most surprising was that the overall use of IVUS in patients undergoing atherectomy was 10.4%, which was not dissimilar to the overall IVUS use in the United States in an all-comer population. Intravascular imaging is of increased importance in calcified lesions and those undergoing treatment with adjunctive atherectomy. Coronary calcification is considerably underappreciated on angiography alone. Recognition of heavily calcified lesions is vital to ensure that adequate lesion preparation occurs before stent implantation. Calcified lesions are associated with higher rates of stent underexpansion, which is an independent risk factor for increased rates of in-stent restenosis. Orbital atherectomy was approved in the United States toward the end of the study period and as a result the study likely represents experience predominantly with rotational atherectomy. Intravascular imaging–based studies have demonstrated the varied mechanisms and impacts of the two devices. Building on the study by Desai and colleagues with data from more recent years once available would provide important insight given the known safety of IVUS with orbital atherectomy demonstrated in both a clinical trial and real-world setting. Further insights into the role of intravascular imaging and the treatment of calcified coronary disease will likely come from the ongoing ECLIPSE (NCT03108456), Disrupt CAD III (NCT03595176), and ILLUMIEN IV: Optimal PCI (NCT03507777) clinical trials.