The iDissection Classification trial results published in the Journal of Invasive Cardiology have shown that with the use of intravascular ultrasound (IVUS) investigators were able to identify more dissections following percutaneous transluminal angioplasty than with angiography.
Post-percutaneous transluminal angioplasty (PTA) dissections are often overlooked, underdiagnosed and left untreated. These dissections can compromise clinical outcomes in both the short and long term. The use of intravascular ultrasound (IVUS) has been found to help visualise the presence and severity of dissections not typically seen on angiography.
In the iDissection study, 15 patients with femoropopliteal disease were treated with atherectomy and adjunctive PTA. Angiographic and IVUS images were obtained at baseline, post-atherectomy and post-angioplasty and evaluated for the presence and severity of dissections. Dissections seen on angiography were graded per the NHLBI scale, and IVUS images were graded using the iDissection classification. All images were independently adjudicated by multiple core laboratories. While angiography identified eight dissections, IVUS revealed 46 dissections—a ratio of 6:1. The iDissection study reveals that significant dissections may not be thoroughly observed with angiography yet are substantially more visible when using IVUS, potentially altering the course of patient treatment in real-time.
“In this small series of patients undergoing atherectomy, there were significantly more dissections noted by IVUS when compared to cine angiography. Angiography has been the main modality used for evaluating the peripheral arteries, but it has consistently under-estimated the severity of calcium, the presence of thrombus, the true vessel size, and lesion severity. In contrast to the NHLBI classification, the iDissection classification reveals the extent of injury and its depth. Pathologic studies have shown that deeper injuries into the media and adventitia correlate with loss of patency and increase in TLR rate. These deeper injuries were also identified on IVUS. The identification of deeper injury that cannot be seen on angiography may offer an explanatory mechanism for the occurrence of restenosis in otherwise successful procedures as seen on angiography following atherectomy. Although data indicate that atherectomy reduces angiographic dissections and stenting compared to balloon angioplasty, this concept may need to be revisited with IVUS-based imaging,” the writers explain.
“Angiography is a suboptimal test to visualise the peripheral arteries. It underestimates vessel size, the presence and extent of calcium, thrombus and stenosis, and does not give a clear picture of optimal stent expansion and apposition. Moreover, the iDissection data confirm that angiography seriously underestimates the presence and severity of dissections following endovascular intervention,” commented Nicolas W Shammas, Founder and Research Director, Midwest Cardiovascular Research Foundation, Davenport, USA. “The iDissection study validates the need for more sophisticated imaging, such as IVUS, to evaluate acute procedural results.”