Intravascular Ultrasound for the Diagnosis and Treatment of Left Main Coronary Artery Disease

Role of IVUS in the rectification of angiographically judged ramus intermedius and its clinical significance

Background

Due to the technical limitations of coronary artery angiography (CAG), ramus intermedius (RI) is sometimes difficult to distinguish from a high-origin obtuse marginal branch or a high-origin diagonal branch. This study sought to investigate the role of intravascular ultrasonography (IVUS) in the rectification of angiographically judged RI.

Methods

This study retrospectively analyzed 165 patients who were reported to have an RI based on CAG and underwent IVUS implementation from 02/01/2009 to 31/12/2019 in Zhongshan Hospital, Fudan University. Taking IVUS as the gold standard, we calculated the accuracy of RI identification by CAG and evaluated the impact of RI on revascularization strategy.

Results

Among the 165 patients, 89 patients (54%) were demonstrated to have an RI on IVUS (IVUS-RI), 32 patients (19%) were identified to have a high-origin diagonal branch on IVUS (IVUS-h-D), and 44 patients (27%) had an actual high-origin obtuse marginal artery on IVUS (IVUS-h-OM). Among 84 patients who underwent one-stent crossover stenting because of left main furcation lesions (48 patients in the IVUS-RI group, 12 patients in the IVUS-h-D group, and 24 in the IVUS-h-OM group), 14.6% of patients in the IVUS-RI group, 33.3% in the IVUS-h-D group and 0% in the IVUS-h-OM group had CAG-RI compromise (P = 0.02), which was defined as severe stenosis of the RI ostium (> 75%) or significant RI flow impairment (TIMI < 3).

Conclusions

Only 54% of CAG-RIs were confirmed by IVUS, which indicates the necessity of preintervention IVUS to distinguish real RIs from other branches in LM furcation lesions.

Intravascular ultrasound of normal left main arteries: Insights for stent optimization and standardization

Left main (LM) lumen diameters >4 mm are the norm and diameter >4.5 mm is present in almost 50% of patients by intravascular ultrasound (IVUS). Normal LM minimum lumen area averages 14.1 mm² for women and 16.2 mm² for men, requiring an area stenosis of 57-63% for LM lesion to be hemodynamically significant using the prevailing criterion of 6 mm² as a cut-off for revascularization. Incomplete LM visualization with IVUS is common (68%) without dedicated and specific LM IVUS techniques.

Operator Experience and Outcomes After Left Main Percutaneous Coronary Intervention

PURPOSE OF REVIEW

This review was performed with the goal of summarizing the role of operator experience in the treatment of severe left main stenosis by percutaneous intervention techniques.

RECENT FINDINGS

The Evaluation of XIENCE versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization (EXCEL) trial demonstrated that percutaneous coronary intervention and coronary artery bypass grafting had similar clinical outcomes for severe left main disease. However, PCI of the left main coronary stenosis is considered to be a high-risk intervention because of the large area of myocardium at jeopardy that can quickly cause hemodynamic compromise. Operator experience and familiarity with the use of hemodynamic support devices, plaque modification techniques, and intravascular imaging tools is associated with better clinical outcomes. In patients with severe left main stenosis undergoing percutaneous coronary intervention by high-volume operators, the clinical outcomes are superior.