Change of therapeutic strategy based on intravascular ultrasound images in angiographically equivocal findings

Despite careful evaluation of multiple projections, coronary angiography may give ambiguous results of lesion severity. The purpose of this study was to analyze the impact of ultrasound imaging on revascularization treatment strategy in angiographically ambiguous findings. We reviewed our experience with such equivocal angiographic findings before intervention in 31 patients (34 lesions) who had additional intravascular ultrasound (IVUS) to clarify coronary anatomy. Intervention was felt to be indicated if area stenosis by IVUS exceeded 50 % in the left main or 75 % in other major coronary arteries. To evaluate the clinical efficacy of IVUS based management strategies, all patients had clinical follow-up after 1 year. Seven of nine ostial lesions were overestimated by angiography, but two of three left main lesions were found to be significant. Seven lesions in one of the proximal coronary arteries whose significance was difficult to judge by angiography were found not to be significant by IVUS, whereas in the other four severe obstruction was confirmed. Membranes by angiography corresponded to remnants of ruptured plaques by IVUS in all five patients. However, significant narrowing was found in only two patients. Side branch ostial lesions were ruled out by IVUS in all four instances. Two patients with unstable angina but normal angiograms showed complex atherosclerotic plaques in the left coronary artery. IVUS led to a change of therapy in 21 patients (revascularization instead of conservative treatment in two and cancellation of initially intended intervention in 19). At follow-up examination, 17 of these 21 patients were free of cardiac symptoms. Interventions at the site thought not severely diseased by IVUS had to be performed in two patients with persistent angina who were afterwards free of symptoms. One patient with persistent chest pain had a second coronary angiogram during the follow-up period, but conservative therapy was continued. Evaluation was impossible in one patient because of bypass surgery due to another coronary lesion. In conclusion, IVUS was clinically useful in patients with angiographically ambiguous findings and resulted in a change of therapy in 21/31 patients obviating interventions in 19 patients with excellent clinical results.