Disclosures: Dr. Ahmed reports no conflicts of interest regarding the content herein.

Dr. Syed Ahmed can be contacted at syedmashoodahmed@hotmail.com.

Chronic total occlusion of a coronary artery is characterized by occlusion for more than three months with distal collateralization from the proximal segment of the occluded vessel or from another vessel. As collateral vessels are unable to supply sufficient blood to the myocardial bed, anginal symptoms result, and ischemia can be seen on a stress test. Patients are usually referred for coronary angiography due to an abnormal stress test or due to anginal symptoms. The incidence of chronic total occlusion is between 15-30%.^1,2 CTOs used to be a common cause for referral for coronary artery bypass graft surgery (CABG). However, recent advances allow CTOs to be treated with percutaneous intervention. At this time, success rates for percutaneous intervention are between 65-80% and are steadily improving. Common reasons for referral for percutaneous intervention of a CTO are prior history of CABG or if patient is a poor surgical candidate. Successful percutaneous treatment results in improvement of anginal symptoms, but may also improve left ventricular (LV) dysfunction.^4,5 

Case report

A 76-year-old female with a history of hypertension and atherosclerotic coronary artery disease came to our community hospital for a pre-op cardiac evaluation. She had a diagnostic coronary angiogram in 2010 showing a 50-60% discrete atherosclerotic stenosis in the proximal right coronary artery (RCA), distal left circumflex (LCX), and 50% stenosis in the mid-left anterior descending coronary artery (LAD). The patient reported a sedentary lifestyle, along with shortness of breath and tiring easily on exertion. She was recently diagnosed with a malignant mass on her left breast requiring lumpectomy with lymph node exploration during the surgery. Due to her limited functional capacity (<4 METS [metabolic equivalents]), and her symptoms of fatigue and dyspnea on exertion (could represent angina equivalent), she underwent a Lexiscan Cardiolite stress test showing moderate area of ischemia in the inferior wall with mild to moderately reduced LV systolic function, considered high-risk scintigraphic findings. As she has prior established moderate coronary artery disease, it was decided to proceed with coronary arteriography. After a detailed discussion with the patient, her primary care physician, and surgeon, it was agreed that a bare-metal stent would be deployed if obstructive disease requiring percutaneous intervention was discovered.

A diagnostic coronary angiogram via a transfemoral approach showed two-vessel atherosclerotic obstructive coronary artery disease. The proximal right coronary artery was chronically occluded with collaterals from the left system (Figure 1). To permit breast surgery in the near future, the patient and her primary care physician agreed to percutaneous intervention with deployment of a bare-metal stent. Our plan was to attempt to recanalize the CTO, and if successful, intervene on an obtuse marginal branch in the next few days in order to decrease radiation and contrast load.

Various techniques are available to recanalize CTOs, including the LAST (limited antegrade subintimal tracking), CART (controlled antegrade and retrograde subintimal tracking), reverse CART, and STAR (subintimal dissection and distal reentry) techniques. Antegrade approaches include the STAR and LAST techniques. Usually a wire is introduced in an antegrade fashion, with continued advancement of the wire in the true lumen or in the subintimal space (wire drilling). If the wire is in the subintimal space, the operator attempts to reenter in the true lumen (STAR technique) under fluoroscopy or by using contrast injected through a microcatheter placed at the proximal cap (contrast-guided STAR). In the LAST technique, the operator attempts to reenter in the true lumen distal to the occlusion by making an acute bend in the wire or with the help of a Venture catheter (Vascular Solutions).⁶ Another way to reenter the true lumen is by using a Stingray balloon. The Stingray balloon is a flat-shaped balloon with two side exit ports. The Stingray guide wire can be directed toward one of the two side ports of the Stingray balloon under fluoroscopic guidance to reenter the distal true lumen.⁷

In the CART technique, a wire is introduced both antegrade and retrograde to the occluded segment. A balloon is inflated over the retrograde guide wire, followed by advancement of the antegrade guide wire into the distal true lumen (controlled antegrade and retrograde tracking and dissection [CART]).⁸ Or, the reverse CART technique can be attempted by inflating over the antegrade guide wire, followed by advancement of the retrograde guide wire into the proximal true lumen.⁶

Since the antegrade approach has been reported to have higher success⁹, it was decided to proceed using this approach. A 6 French (Fr) sheath was inserted and a 6 Fr Judkins right guide catheter (Cordis) used to engage the right coronary system. A chronic, long segment of occlusion appeared unfavorable for intervention, but the absence of a side branch, bridging collaterals, and the presence of a tapering end (nub) were suggestive of a favorable outcome. Due to these favorable features, it was decided to attempt to re-canalize the CTO. In case the attempt was not successful, we planned to transfer the patient’s tertiary care for re-attempt percutaneous coronary intervention or CABG.

A long 360mm BMW (Balance Middle Weight) wire (Abbott Vascular) was introduced into the proximal segment of the right coronary artery. After a few initial unsuccessful attempts, we were able to penetrate the proximal cap. A 2.0mm OTW (over the wire) Sprinter balloon (Medtronic) was used for support. As a result of this initial success, we decided to pursue the antegrade “wire drilling” technique. The lesion was crossed with the workhorse wire. However, we were unable to cross the lesion with a balloon. The 2.0 x 12mm Sprinter balloon was exchanged to a 2.0 x 6mm Sprinter balloon, and we were successful in crossing the lesion. The balloon was parked distal to the lesion and the wire was pulled out. A small amount of contrast was injected through the balloon lumen that confirmed the intraluminal position of the balloon. Sequential angioplasty of the entire CTO lesion was performed. After successful re-canalization of the vessel, intracoronary nitroglycerine was given to improve low-flow spasm. A rapid exchange 2.75 x 32mm VeriFlex (Boston Scientific) bare-metal stent was deployed in the proximal RCA on nominal pressure. A successful angiographic outcome with no residual stenosis was observed (Figure 2). Due to the increased radiation load (total fluoroscopy time was 17.3 minutes; the patient received follow-up at one week), intravascular ultrasound was not performed and the procedure was concluded at that time. As an anticoagulant of unfractionated heparin could be reversed in case of periprocedure complications, we chose to use heparin during the procedure. The patient was not on dual antiplatelet therapy prior to the procedure. We therefore administered two boluses of eptifibatide towards the end of the procedure, and the patient was later started on clopidogrel. She was brought back after few days and underwent successful percutaneous intervention of the obtuse marginal branch.

References

1. Kahn JK. Angiographic suitability of catheter revascularization of total coronary occlusions in patients from a community setting. Am Heart J. 1993 Sep;126(3 Pt 1):561-564.
2. Christofferson RD, Lehmann KG, Martin GV, Every N, Caldwell JH, Kapadia SR. Effect of chronic total coronary occlusion on treatment strategy. Am J Cardiol. 2005: 95: 1088-1091.
3. Suero JA, Marso SP, Jones PG, et al. Procedure outcomes and long-term survival among patients undergoing percutaneous intervention of a chronic total occlusion in native coronary arteries: a 20-year experience. J Am Coll Cardiol. 2001; 38: 409-414.
4. Baks T, Van Geuns R-J, Dunker DJ, Cademartini F, Mollett NR, Serruys PW, De Feyter P. Prediction of left ventricular systolic function after drug eluting stent implantation of chronic total occlusion. J Am Coll Cardiol. 2006; 47: 721-725.
5. Kirschbaum SW, Baks T, Van Den Ent M, Sianos G, Serruys PW, De FeyterP, Van Geuns R-J. Evaluation of left ventricular function after three after percutaneous recanalization of chronic total occlusions. Am J Cardiol. 2008; 101: 179-185.
6. Michael TT, Papayannis AC, Banerjee S, Brilakis ES. Subintimal dissection/reentry strategies in coronary chronic total occlusion interventions. Circ Cardiovasc Interv. 2012 Oct; 5(5): 729-738. doi: 10.1161/CIRCINTERVENTIONS.112.969808.
7. Werner GS. The BridgePoint devices to facilitate recanalization of chronic total coronary occlusions through controlled subintimal reentry. Expert Rev Med Devices. 2011 Jan; 8(1): 23-29. doi: 10.1586/erd.10.76.
8. Surmely JF, Tsuchikane E, Katoh O, Nishida Y, Nakayama M, Nakamura S, Oida A, Hattori E, Suzuki T. New concept for CTO recanalization using controlled antegrade and retrograde subintimal tracking: the CART technique. J Invasive Cardiol. 2006; 18: 334-338.
9. Dai J, Katoh O, Kyo E, Tsuji T, Watanabe S, Ohya H. Antegrade approach to stumpless chronic total occlusion of ostial left anterior descending artery: first using a side branch cutting technique. Hellenic J Cardiol. 2014 Jan-Feb; 55(1): 70-76.