Case Report
Successful Revascularization of a Long Chronic Total Occlusion With Blunt Microdissection Complicated by Coronary Artery Dissect
November 2004
Percutaneous revascularization of chronic total occlusions (CTOs) represents an important clinical challenge in interventional cardiology. A CTO is defined as, “an obstruction of a native coronary artery for greater than 30 days with no luminal continuity and with thrombolysis in myocardial infarction (TIMI) flow grade 0 or 1.”1 These lesions account for approximately 10% of all percutaneous transluminal coronary angioplasty (PTCA) procedures.2 However, the angioplasty of CTOs is frequently limited by both an inability to successfully pass a guidewire across the occlusion and the higher incidence of restenosis than that of subtotal stenoses.3–6
Improvements in angioplasty equipment, operator technique, and the introduction of innovative devices designed specifically for CTOs have improved the likelihood of successful recanalization. In this report, we describe a case where blunt microdissection using the LuMend Frontrunner Catheter (LuMend Inc, Redwood City, California) to facilitate guidewire access across a CTO resulted in coronary artery dissection.
Case Report. A 72-year-old man with normal left ventricular function, chronic stable angina, and the cardiovascular risk factors of hypertension, diabetes mellitus, and tobacco use presented with a change in anginal status. Despite therapy consisting of metoprolol, irbesartan, aspirin, and simvastatin, and a blood pressure 110/70 with resting heart rate 55 beats/min, he experienced lifestyle-limiting exertional angina. Angiography demonstrated nonobstructive disease of the right coronary artery (RCA), normal circumflex artery, and a long total occlusion of the left anterior descending artery (LAD) with a second total occlusion just distal to a small diagonal branch between the diagonal artery and the recanalization of the LAD.
The patient refused elective bypass surgery but was accepting of emergency surgery, if necessary, for a complication of percutaneous revascularization. He was brought to the catheterization laboratory for PTCA of the mid LAD CTO. The indication for percutaneous intervention was medically refractory angina and refusal of cardiac surgery. There was faint antegrade filling of the mid LAD. The distal LAD did not fill from left coronary artery (LCA) injection (Figure 1). Grade 3 collateral filling from the RCA was observed to fill the distal LAD (Figure 2). Both femoral arteries were cannulated and simultaneous injection of the RCA and LCA was performed. A long total occlusion of the mid LAD was noted (Figure 3). Initial attempt for 30 minutes to cross the CTO with several guidewires, including hydrophilic guidewires, was unsuccessful. The more proximal aspect of the occlusion was recanalized by blunt microdissection with the Frontrunner Catheter, a novel catheter-based device indicated for the revascularization of CTOs (Figure 4). This allowed a Whisper Wire 0.014 in. 300 cm (Guidant) hydrophilic-coated guidewire to be advanced into the diagonal branch and ultimately a second Whisper Wire 0.014 in. 300 cm (Guidant) passed across the more distal occlusion and was advanced into the apical LAD (Figure 5). The guidewire in the diagonal artery allowed us to direct a second guidewire away from the diagonal branch.
Angiography following the inflation of a 2.5 mm x 20 mm balloon revealed a dissection of the mid LAD (Figure 6). Angiography, subsequently, in multiple views revealed subintimal passage of the guidewire in a false lumen throughout the entire course of the distal LAD that was not evident from the AP cranial working view, but was clearly evident in the lateral view (Figure 7).There was excellent antegrade flow in both true and false lumens. Multiple attempts to gain access to the true lumen including using a second wire with the first wire left in the dissection, were unsuccessful, with the wire continuously entering the dissection. The patient was asymptomatic, and a decision was made to refrain from stent deployment at that time and allow the dissection time to heal.
The patient returned to the laboratory 7 weeks later for a diagnostic cardiac catheterization. Angiography revealed a severe, long narrowing in the LAD at the prior site of total occlusion, a discrete healed area of chronic dissection just distal to this narrowing, and 2 clear lumens in the mid LAD with antegrade flow (Figure 8).
The patient was brought back to the catheterization laboratory for a planned intervention with drug-eluting stents. The LAD lesion was crossed easily with a Stabilizer plus 0.014 in. 300 cm guidewire (Cordis Corporation, Miami Lakes, Florida) and CYPHER (Cordis) Sirolimus-eluting coronary stents were successfully deployed with an excellent final angiographic result (Figure 9).
Discussion. The revascularization of CTOs is technically difficult and remains a challenge for percutaneous coronary interventions. Although the development of collateral flow may maintain myocardial viability and prevent resting ischemia, patients with CTOs often present with exertional angina.
Crossing the complex lesion and reentering into the true lumen remains the key step that limits the overall success of percutaneous procedures. Successful recanalization has traditionally been achieved in only up to 60% of chronic occlusions using conventional techniques.3,7,8 The availability of new specialized guidewires designed to cross occluded arteries has only modestly improved procedural success rates. Allemann reported a success rate of 64% using the Magnum wire (Schneider, Zurich, Switzerland).9 Reimers achieved a crossing success rate of 71% using the Athlete wire (Asahi Intecc Co., LTD, Seto, Japan) in synergy with a floppy hydrophilic wire and low-profile balloon.10 Trials utilizing the Terumo Crosswire (Terumo, Tokyo, Japan) have demonstrated procedural success in 42% of situations when conventional guidewires have failed11 and in approximately 75% of cases when used as a first intentionguidewire.12 Saito reported improved procedural success rates using tapered-tip guidewires.13 The use of a laser guidewire, as documented in the European TOTAL study, was not more effective than conventional mechanical guidewires in crossing CTOs.14
To overcome the obstacles associated with crossing occluded arteries, new innovative catheter-based systems have recently been introduced. These devices may substantially improve procedural success in cases of CTO that would have otherwise been abandoned or referred for coronary artery bypass surgery. In this case, we utilized the Frontrunner Catheter, a novel device that separates the atherosclerotic plaque by blunt microdissection, facilitating passage of a conventional guidewire followed by standard angioplasty and stenting. Whitlow recently reported a 71% procedural success rate using the Frontrunner Catheter in 100 patients who failed conventional recanalization with various guidewires.15
Wire-induced vessel perforation and dissection are complications associated with percutaneous revascularization of CTOs.16 In a multicenter trial, use of the Frontrunner Catheter resulted in perforations requiring pericardiocentesis (2%), small contained perforations (4%), and ostial right coronary artery dissection (1%).15 In this case, following microdissection with the Frontrunner Catheter, a large coronary dissection was created during an attempt to establish a connection with the distal true vessel lumen using a guidewire. This case demonstrates that successful revascularization can be accomplished despite the initial perception of procedure failure. Prolonged attempts at placing the wire in the true lumen at the index intervention were unsuccessful. However, the Frontrunner Catheter was able to reestablish antegrade flow. At 7 weeks, the vessel had healed in a very favorable fashion allowing easy passage of a guidewire into the true lumen and, ultimately, successful revascularization.
After successful recanalization with PTCA, significantly higher rates of restenosis have been observed with chronic total occlusions than those associated with previously dilated subtotal stenoses.2,5 However, several randomized trials have demonstrated that coronary stent implantation significantly reduces restenosis and reocclusion rates compared with balloon angioplasty alone.17-19 The advent of drug eluting stents now allows us to alter the biologic response to arterial injury. Although the efficacy of drug-eluting stents for the treatment of chronic total occlusions has not been established, they offer promise that the impressive results reported for nonoccluded vessels may also be seen in this high-risk population.
Despite the limitations, successful revascularization of CTOs is associated with favorable outcomes, including improved left ventricular function.20-22 A recent prospective study demonstrated that successful PCI was associated with low rates of coronary artery bypass surgery, lower cumulative incidences of cardiac death and myocardial infarction, and better clinical status with less angina and improved exercise tolerance at 1 year.23 Additionally, long-term follow-up revealed that successful revascularization of CTOs was independently associated with improved 10-year survival.16
This case illustrates that, with the Frontrunner Catheter, if initial success is hampered by continuous subintimal wire placement, subsequent attempts may succeed after allowing the subintimal dissections to heal, especially if the catheter was able to cross a large segment of total occlusion.
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