Acute coronary artery closure following intracoronary ultrasound examination

Acute coronary artery occlusion following intravascular ultrasound examination

Intravascular ultrasound is considered as having few complications, most of them are just a transient coronary spasm. However, we experienced one case of acute left anterior descending coronary artery occlusion following an intravascular ultrasound study during the intervention and this was treated successfully with cardiopulmonary resuscitation and stent implantation.

Acute occlusion of the left main coronary artery following intracoronary ultrasound examination

Intracoronary ultrasound (ICUS) is generally considered as safe procedure, with a low complication rate. We describe a nearly fatal complication of a diagnostic ICUS study that was treated successfully with stent implantation in the left main coronary artery and discuss the indications and remaining risks of this procedure.

[Intracoronary ultrasound: A necessary tool for stent implantation? Arguments in against]

Intracoronary ultrasound has shown the little reliability of angiography to predict the interaction of stents with the arterial wall. In spite of implanting the stents with high pressures and a good angiographic result, a great proportion are still incompletely expanded. The use of intracoronary ultrasound as a guide for stent implant allows us to optimize the degree of expansion and apposition of the stent to the arterial wall, achieving greater intraluminal dimensions than with angiography. Nevertheless, this strategy is not necessarily translated in a clear clinical benefit. The rate of acute and subacute complications of stents implanted under angiographic control with high pressures and treatment with ticlopidine and aspirin is less than 1% and identical to the studies that use intracoronary ultrasound to optimize stent deployment. At the present time, it has not been documented either that the optimization of stent deployment with intracoronary ultrasound significantly reduces the rate of restenosis, the incidence of target vessel revascularization or the rate of major adverse cardiac events in mid-term follow-up. In addition, the use of intracoronary ultrasound to optimize stent deployment adds a small risk to the procedure, extends the time of occupation of the cardiac catheterization laboratory and prohibitively increases the costs of coronary stenting them being already high ones. Thus, the universal use of coronary intracoronary ultrasound to optimize stent deployment seems not to be, at present, a useful strategy.

Role of intravascular ultrasound imaging in identifying vulnerable plaques

A plaque that has a large lipid core and a thin fibrous cap may undergo rupture. Once it ruptures, it may lead to thrombus formation and subsequent vessel occlusion. To identify unstable plaques before they rupture is essential for clinical management and patient's prognosis. Intravascular ultrasound (IVUS) opens a new window for the assessment of plaque morphology to identify vulnerable plaques and plaque rupture. We examined 144 patients with angina and ischemic ECG changes using IVUS. Ruptured plaques, characterized by a plaque cavity and a tear on the thin fibrous cap, were identified in 31 patients (group A) of which 23/31 (74%) clinically presented as unstable angina. Plaque rupture was confirmed by injecting contrast medium filling the plaque cavity during IVUS examination. Of the patients without plaque rupture (group B, n = 108), only 19 (18%) had unstable angina. No significant differences between the 2 groups were found concerning the vessel and plaque areas (p > 0.05). The percent stenosis in group A (56.2 +/- 16.5%) was significantly lower than in group B (67.9 +/- 13.4%) (p < 0.001). Area of the plaque cavity in group A (4.1 +/- 3.2 mm2) was significantly larger than the echolucent zone in group B (1.32 +/- 0.79 mm2) (p < 0.001). The plaque cavity/plaque ratio in group A (38.5 +/- 17.1%) was larger than the echolucent area/plaque ratio in group B (11.2 +/- 8.9%) (p < 0.001). The thickness of the fibrous cap in group A (0.47 +/- 0.20 mm) was significantly thinner than that (0.96 +/- 0.94 mm) in group B (p < 0.001).

CONCLUSIONS

Plaques seem to be prone to rupture when the echolucent area is larger than 1 mm2, the echolucent area/plaque ratio greater than 20% and the fibrous cap thinner than 0.7 mm. IVUS has the capacity of identifying plaque rupture and vulnerable plaques. This may have potential influence on patients management and therapy.