Angiographically unexplained myocardial ischaemia diagnosed by intravascular ultrasound as high-grade coronary artery stenosis with extension into the main stem

History and admission findings: For seven weeks a 57-year-old man had been complaining of recurrent non-radiating retrosternal pain and pressure on sl ightest exertion. Admission physical examination was unremarkable except fo r evidence of peripheral vascular disease. Cardiovascular risk factors were hypertension, hyperlipoproteinaemia and obesity. Investigations: The resting ECG was unremarkable. Objective signs of myocar dial ischaemia were produced in the exercise ECG (angina at 100 Watt, negat ive T waves in V2 to V6 and borderline S-T depression in V4). Myocardial sc intigraphy showed reversible reduced perfusion of the anterior wall near th e apex and also of the apex and septum. Left ventricular (LV) angiography d emonstrated a normally contracting LV, while selective coronary angiogram r evealed a 20% reduction in caliber of the proximal branch of the anterior i nterventricular branch (AIVB), with otherwise normal coronary arteries. Sub sequent intravascular ultrasound (IVUS) showed a circular echo-poor 80% ste nosis at the origin of the AIVB with extension to the main stem. Treatment and course: A bypass from the internal mammary artery to the AIVB and an aortocoronary venous bypass to the intermediate branch were perform ed. The patient was free of symptoms postoperatively. Conclusion: If cases where there is a discrepancy between clinical and coro nary angiographic findings - the latter being unclear or inconsistent, espe cially in the area of the left main stem, bifurcations or vessel origin - I VUS may contribute decisively to demonstrating coronary anatomy or patholog y, and to indicating the type of revascularizing measures.