The role of intravascular ultrasound in contemporary percutaneous coronary intervention practice
2017-02-23T23:38:21Z (GMT) by
Grey-scale Intravascular ultrasound (IVUS) has provided significant insights into atherosclerosis and consequently has helped to shape interventional cardiology practice. In the era of contemporary percutaneous coronary intervention (PCI) practice using newer intra coronary imaging modalities like virtual histology IVUS (VH-IVUS, Near infra red spectroscopy (NIRS) and Optical Coherence Tomography (OCT), the question remains if IVUS is relevant. In this thesis, we sought to determine the continuing usefulness of IVUS. In chapter 2 of this thesis, we reviewed the evidence for the usefulness of IVUS of IVUS especially in the complex coronary lesion subsets like left main stem, ostial coronary, bifurcation, calcified lesions and chronic total occlusions. We showed that IVUS still has a very useful role to play in especially in PCI of these complex lesion subsets. In chapter 3, we showed the positive relationship between conventional cardiovascular risk factors and atherosclerotic plaque volume in the left main stem. We assessed total atheroma volume and percent atheroma volume in 105 patients who had IVUS performed for assessment of intermediate lesion in the LMS. Using multivariate analysis, we determined that male gender and positive family history predicted increased atherosclerotic plaque burden. This knowledge may help us to target this high-risk patient cohort for early intervention in the LMS. In chapter 4, using IVUS, we studied 156 patients with angiographic intermediate or significant coronary lesions involving the LMS or proximal left anterior descending or left circumflex artery lesions (DV) that were referred for morphologic assessment of atherosclerotic plaque. We showed that irrespective of the indication of the IVUS i.e. intermediate lesions in the LMS or proximal DV, distal LMS is invariably involved. This information is crucial because it will help interventional cardiologist achieve optimal stent result especially in the distal LMS. In chapter 5, we studied the long term clinical outcome of 91 patients who had IVUS for intermediate LMS lesions, who were then referred to conventional management strategies of PCI, Coronary artery bypass surgery (CABG) or medical therapy (MT). The objective of this study was to determine the relevance of conventional IVUS diagnostic paradigms in the LMS – minimal luminal diameter (MLD) of < 2.8mm and minimal luminal area (MLA) < 6mm². The primary end point was major adverse cardiac events (MACE) defined as recurrent angina (defined as angina > CCS 2), need for target lesion or target vessel revascularization (TLR/TVR) or CABG, requirement for admission (due to angina, acute myocardial infarction [AMI] and all cause mortality. We found that patients who underwent PCI or CABG for significant LMS lesion using these LMS IVUS diagnostic paradigms had good long-term clinical outcome. Deferral to medical therapy on the basis of intermediate LMS lesion based on LMS IVUS MLD > 2.8mm and MLA > 6mm² were associated with low MACE rates. We concluded that these traditional IVUS diagnostic paradigms are still relevant and safe. In conclusion, we confirmed that IVUS still has a vital role to play, especially in LMS, in the era of contemporary PCI practice.