Case presentation

A 61-year-old woman with hypertension, diabetes mellitus, hyperlipidemia, and a strong family history of premature coronary disease presents with a 2-month history of exertional angina. The presence of an abnormal noninvasive test with an inferolateral stress-induced perfusion defect, along with continued symptoms despite medical therapy, prompted referral for cardiac catheterization. Medications included 325 mg of aspirin, high-dose niacin, omega-3 fatty acid, metoprolol, and sublingual nitrates as needed for angina. Her physical examination, 12-lead electrocardiogram, and routine preprocedural laboratory evaluations were unrevealing.

Cardiac catheterization

Cardiac catheterization revealed preserved left ventricular systolic function and multivessel coronary disease, with severe discrete stenoses of the proximal right coronary artery and left anterior descending artery and an angiographically normal circumflex artery (Figures 17-1, 17-2 and Videos 17-1, 17-2). The attending physician discussed revascularization options, and the patient chose percutaneous coronary intervention of both the right coronary and left anterior descending coronary arteries with drug-eluting stents instead of bypass surgery. She returned to the cardiac catheterization laboratory the next morning following a dose of 300 mg of clopidogrel taken the night before. The operator began with the left anterior descending artery. This was successfully treated with a 2.5 mm diameter by 18 mm long, drug-eluting stent (zotarolimus), with an excellent angiographic result (Figure 17-3). The operator engaged a 6 French right Judkins 4.0 guide catheter in the right coronary artery and easily crossed the stenosis with a floppy-tipped guidewire and predilated the lesion to 10 atmospheres with a 2.5 mm diameter by 15 mm long compliant balloon. The operator then attempted, but failed to pass, a 2.5 mm diameter by 24 mm long drug-eluting stent (zotarolimus) across the lesion. The stent met significant resistance at the site of a bend in the proximal right coronary artery (see Figure 17-1, arrow), and the attempt caused the guide to inadvertently disengage, resulting in loss of guidewire access to the distal right coronary artery. Angiography following reengagement of the guide catheter showed no obvious dissection but a persistent residual stenosis at the site of the balloon-dilated lesion (Video 17-3).

FIGURE 17-1 This is a left anterior oblique projection of the right coronary artery demonstrating a severe stenosis in the proximal segment (arrow).

FIGURE 17-2 This angiogram of the left coronary artery in a right anterior oblique projection with cranial angulation reveals a severe stenosis of the proximal segment of the left anterior descending coronary artery (arrow) at the bifurcation of a small caliber diagonal artery.

FIGURE 17-3 Following stenting of the left anterior descending artery, an excellent angiographic result was noted; the small diagonal branch occluded after stenting.

At this point, the operator chose an extra-support guidewire to facilitate stent placement (Mailman, Boston Scientific). Although the wire advanced with ease to a distal location in the posterolateral branch of the artery, the patient soon complained of severe chest pain associated with ST-segment elevation on the monitored leads. Fearing abrupt vessel closure, the operator repeated right coronary angiography, and noted an extensive spiral dissection along the entire course of the right coronary artery with closure of the posterolateral branch (Figure 17-4 and Video 17-4). The operator removed the extra-support wire, replacing it with a floppy wire, and successfully positioned this wire in the posterior descending artery (Video 17-5). Unable to pass short bare-metal stents beyond the proximal lesion, the operator consulted surgery for consideration of emergency bypass surgery.

FIGURE 17-4 The extensive spiral dissection of the right coronary artery is shown on this left anterior oblique projection.

Postprocedural course

An intraaortic balloon pump was placed and, although the patient remained hemodynamically stable, chest pain and ST-segment elevation continued and she was emergently transferred from the cardiac catheterization laboratory to the operating room, where she underwent a single-vessel bypass consisting of an off-pump, saphenous vein graft to the posterior descending artery. Her postoperative course was uneventful and she was discharged 7 days later. She remained free of angina at 6-month follow-up.

Discussion

Well known to experienced interventional cardiologists, this case exemplifies the fact that a case cannot be declared “easy” until it is successfully completed. The operator’s difficulty in passing the stent and the subsequent development of an extensive dissection could not be anticipated by the deceptively straightforward angiographic appearance of the right coronary artery.

Coronary dissection represents a unique complication of percutaneous coronary intervention and, if untreated, can lead to serious sequelae including abrupt vessel closure, periprocedural myocardial infarction, closure of major side branches, vessel perforation, and tamponade. Coronary stents successfully treat most dissections so that, in the current era, the risk of sustained vessel closure or the need for emergency bypass surgery due to a dissection is very rare.

Arterial injury and dissection can be induced by any of the components of the procedure; including insertion of the guide catheter, use of the device to treat the lesion, and placement of the guidewire. Guide-related dissections are often related to the use of large-bore (i.e., 8 French) or aggressive guides (such as an Amplatz curve) in order to provide extra backup. Similarly, dissection may arise when the operator requires additional support and deeply inserts the guide into the artery. Attempts to deeply engage the artery when the guide is not coaxial to the vessel is particularly likely to cause this complication. Coronary dissection may be due to the balloon, stent, or device used to treat a coronary stenosis. Oversizing the balloon or stent, application of high inflation pressure (particularly when a compliant balloon is used), and the use of atherectomy devices are commonly associated with dissection. This is particularly true when certain lesion characteristics are present, including heavy calcification, lesion eccentricity, and severe angulation.

Coronary dissection may be caused by the 0.014 inch guidewire used to direct the balloon and stent catheters; this was the likely mechanism involved in the present case. Any guidewire, but particularly the polymer-tipped and stiff-tipped guidewires employed to cross highly stenosed or occluded arteries, may burrow beneath the plaque and intima, dissecting the artery. In the present case, the initially placed guidewire fell out of the artery when the guide catheter became disengaged and the operator recrossed the freshly ballooned segment with another (and stiffer) guidewire. It is likely that balloon angioplasty created a small, undetected dissection and the wire tip entered the subintimal space via a false lumen within the ballooned segment. Unaware of the malposition of the wire tip, the operator advanced the wire, thus extending the false lumen and propagating the dissection along the entire length of the artery. The stiff shaft of the extra-support wire likely exacerbated this process.

Focal dissections respond well to stenting. It is important to identify the extent of the dissection and to cover both ends of the dissection with a stent. In this case, dissection affected nearly the entire artery; in addition, the initially-encountered difficulty in advancing a stent across the lesion would not allow a stenting option.

In the present era, the need to perform emergency coronary bypass surgery to treat a complication from percutaneous coronary intervention has become very rare.¹ Currently, most emergency bypass operations occur when a dissection in a major artery cannot be stented or when a coronary perforation cannot be controlled by percutaneous means. Unfortunately, emergency bypass surgery in the setting of a failed percutaneous coronary intervention is associated with a high rate of in-hospital death, myocardial infarction, and stroke. Thus, in the event of a large, untreatable dissection, the risk-benefit ratio of surgery must be carefully weighed against the risk of leaving the artery closed and treating the resulting infarction medically. In the present case, the involved physicians and surgeons struggled with the decision to salvage the artery with emergency coronary bypass surgery. Although her continued chest pain and ST-segment elevation suggested the need for surgical treatment, the procedure likely offered only a modest benefit given the size of the right coronary artery. The decision to operate is easier when the affected artery supplies a larger vascular territory. In addition, the involved physicians feared stent thrombosis in the freshly placed stent in the left anterior descending artery induced by the stress of surgery.