Abstract: Background. Left main coronary artery (LMCA) chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study. Methods. We reviewed 4436 CTO-PCIs performed in 4340 patients between 2012 and 2018 at 25 sites. LMCA-CTO-PCI was performed in 20 cases (0.45%). We examined the clinical and angiographic characteristics and procedural outcomes of these cases. Results. Mean patient age was 68 ± 11 years and 65% were men. Most patients (85%) had undergone prior coronary artery bypass graft surgery and had a protected left main. Mean J-CTO score was 2.7 ± 1.3, mean PROGRESS-CTO score was 1.3 ± 1.1, and mean PROGRESS-CTO Complications score was 3.8 ± 1.9. Antegrade-wire escalation was the most common successful crossing strategy (50%), followed by retrograde crossing (30%) and antegrade dissection/re-entry (10%). Technical and procedural success rates were both 85%. One patient with failed LMCA-CTO-PCI had periprocedural myocardial infarction. Median procedure time was 178 minutes (interquartile range [IQR], 123-250 minutes), median contrast volume was 190 mL (IQR, 133-339 mL), and patient air kerma radiation dose was 2.6 Gray (IQR, 1.3-3.9 Gray). Conclusions. LMCA-CTO-PCI is infrequent, is performed mostly in patients with prior coronary artery bypass graft surgery, and is associated with good procedural outcomes.
J INVASIVE CARDIOL 2019;31(7):E220-E225.
Key words: chronic total occlusion, left main coronary artery, percutaneous coronary intervention
Complete occlusion of the left main coronary artery (LMCA) is a rare finding in patients with stable angina who undergo coronary angiography, with an estimated prevalence of 0.04%.1,2 Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) can be performed with favorable outcomes at experienced centers;3 however, little is known about the frequency and outcomes of LMCA-CTO-PCI. We examined a contemporary, multicenter CTO-PCI registry to determine the frequency and outcomes of LMCA-CTO-PCI.
We identified cases of LMCA-CTO-PCI included in the PROGRESS-CTO (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention) registry (NCT02061436) and evaluated the clinical, angiographic, and procedural characteristics and outcomes of these cases (Figure 1). The study was approved by the institutional review board of each center.
Coronary CTOs were defined as coronary lesions with Thrombolysis in Myocardial Infarction (TIMI) grade 0 flow of at least 3-month duration. Estimation of the duration of occlusion was clinical, based on the first onset of angina, prior history of myocardial infarction (MI) in the target vessel territory, or comparison with a prior angiogram. Calcification was assessed by angiography as mild (spots), moderate (involving ≤50% of the reference lesion diameter), or severe (involving >50% of the reference lesion diameter). Moderate proximal vessel tortuosity was defined as the presence of at least 2 bends >70° or 1 bend >90° and severe tortuosity as 2 bends >90° or 1 bend >120° in the CTO vessel. Proximal cap ambiguity was defined as the inability to determine the exact location of the proximal cap of the occlusion due to the presence of obscuring side branches or overlapping branches that could not be resolved despite multiple angiographic projections or by flush ostial occlusion. Interventional collaterals were defined as collaterals considered amenable to crossing by a guidewire and a microcatheter by the operator. A procedure was defined as retrograde if an attempt was made to cross the lesion through a collateral vessel or bypass graft supplying the target vessel distal to the lesion. Antegrade dissection/re-entry (ADR) was defined as antegrade PCI during which a guidewire was intentionally introduced into the subintimal space proximal to the lesion, or re-entry into the distal true lumen was attempted following intentional or inadvertent subintimal guidewire or device crossing.
Technical success was defined as successful CTO revascularization with achievement of <30% residual diameter stenosis within the treated segment and restoration of TIMI grade 3 antegrade flow. Procedural success was defined as the achievement of technical success without an in-hospital major adverse cardiac event (MACE). In-hospital MACE included any of the following adverse events prior to hospital discharge: death, MI, recurrent symptoms requiring urgent repeat target-vessel revascularization with PCI or coronary artery bypass graft (CABG) surgery, tamponade requiring either pericardiocentesis or surgery, and stroke. MI was defined using the Third Universal Definition of Myocardial Infarction (type 4 MI).4 The Japan-CTO (J-CTO) score was calculated as described by Morino et al,5 the PROGRESS-CTO score as described by Christopoulos et al,6 and the PROGRESS-CTO Complications score as described by Danek et al.7
Statistical analysis. Categorical variables are expressed as percentages, while continuous variables are presented as mean ± standard deviation or median (interquartile range [IQR]).
Between January 2012 and November 2018, a total of 4436 CTO-PCIs were performed in 4340 patients at 25 centers in the United States, Europe, and Asia. LMCA-CTO-PCI was performed in 20 cases (0.45%). The baseline clinical characteristics of the LMCA-CTO-PCI patients are shown in Table 1. Mean patient age was 68 ± 11 years and most patients (65%) were men. Cardiovascular risk factors were highly prevalent, and included hypertension (80%), diabetes (30%), dyslipidemia (90%), and smoking (25%). Most patients had undergone prior CABG (85%). Four patients presented with non-ST segment elevation MI, 6 patients presented with unstable angina, 9 patients presented with stable angina, and 1 patient presented with no symptoms. Three procedures (15%) were ad hoc PCIs.
The angiographic and procedural characteristics of the study lesions are summarized in Table 2. The incidence of proximal cap ambiguity and moderate-to-severe calcification was 35% and 75%, respectively. J-CTO score was 2.7 ± 1.3, PROGRESS-CTO score was 1.3 ± 1.1, and PROGRESS-CTO Complications score was 3.8 ± 1.9. At least 1 femoral artery was used for access in all but 1 patient (95%). Intravascular ultrasound was used for crossing or stent optimization in 45% of cases.
Antegrade-wire escalation was the most commonly attempted crossing strategy (90%) and was most frequently the final successful crossing strategy (50%). Retrograde crossing was used in 50% of cases and was the final successful crossing strategy 30% of the time, while ADR was used in 15% of cases and as the final successful strategy in 10%. Retrograde crossing attempts were made via saphenous vein grafts (SVG) 70% of the time and the left internal mammary artery (LIMA) graft was used in 20% of those attempts (Figure 2). Significant disease in the right coronary artery (RCA), defined as at least 1 stenosis >70% with no graft to the RCA with <70% stenosis, was present in 35% of the patients. A left ventricular assist device was used in 20% of the cases (Impella CP in 3 cases and extracorporeal membrane oxygenator in 1 case).
Procedural outcomes are shown in Table 3. Technical and procedural success rates were high (85% for both). Only 1 patient developed an in-hospital MACE (periprocedural myocardial infarction). Three patients had coronary perforations that were treated without pericardiocentesis or emergent surgery and 1 patient developed a femoral pseudoaneurysm that was corrected surgically. Median procedure time was 178 minutes (IQR, 123-250 minutes), median contrast volume was 190 mL (IQR, 133-339 mL), and median patient air kerma radiation dose was 2.6 Gray (IQR, 1.3-3.9 Gray).
The major findings of our study are that LMCA-CTO-PCI: (1) is infrequently performed (0.45% of all CTO-PCI cases), mainly in prior CABG patients; (2) often requires use of the retrograde approach; and (3) is associated with favorable procedural outcomes.
The feasibility of LMCA-CTO-PCI, particularly in patients who refuse CABG or who are deemed inoperable, has previously been demonstrated in a few case reports and also in a 5-patient case series by Flores-Umanzor et al.8-15 These reports are summarized in Table 4.
Most often, patients with LMCA-CTOs are known to present with stable angina.16 However, in the only previously published case series of LMCA-CTO patients who actually underwent PCI, all patients presented with an acute coronary syndrome; 3 patients presented with unstable angina and 2 patients presented with non-ST segment elevation MI. Our study confirmed that a portion of these patients can present with acute coronary syndromes – 50% in our series. An acute coronary syndrome presentation in the context of LMCA-CTO could be explained by factors such as coronary artery disease progression in other native vessels or bypass grafts, as it is known that patients with severe LMCA coronary artery disease typically have multivessel disease, a high burden of atherosclerotic disease, and high-risk plaques.17 Acute occlusion of the RCA in patients with concurrent unprotected LMCA-CTO is likely to be fatal.12
In the series by Flores-Umanzor et al, all patients undergoing LMCA-CTO-PCI had semiprotected LMCA lesions, ie, had one occluded and one patent graft to the circumflex artery or the left anterior descending coronary artery. Similarly, most patients in our series also had semiprotected LMCA, although 3 patients did not have protected LMCA-CTO and all of them underwent successful, uncomplicated LMCA-CTO-PCI (Figure 2). In contrast to the aforementioned case series, in which 4 patients were treated with AWE and 1 patient was treated with the retrograde approach, to the best of our knowledge, our series is the first to report use of ADR for LMCA-CTO-PCI.
Radial access was used in only 15% of our patients, which is likely explained by the need to engage bypass grafts and to obtain strong guide support. From the 10 patients who had a successful retrograde crossing strategy, a saphenous vein graft was used for the retrograde route in 7 patients, the LIMA graft in 2 patients, an epicardial collateral in 1 patient, and a septal collateral in 1 patient in whom a saphenous vein graft had been used as well. Use of grafts for retrograde LMCA-CTO-PCI is consistent with data from multiple prior CTO-PCI series, which have shown that both patent and even occluded grafts can be used for retrograde access.18,19 Bypass grafts are, in general, wired more easily and are less tortuous than septal and epicardial collaterals. However, in patients with prior CABG (common in the LMCA-CTO cohort), a perforation can lead to loculated effusion, which can cause cardiac chamber compression and cardiogenic shock.20 Furthermore, because of the acute angulation at the saphenous vein graft touchdown point, retrograde wiring of the native proximal vessel can be challenging. Compromising the flow through a LIMA graft can cause ischemia in a large myocardial territory and cause hemodynamic instability, yet Tajti et al demonstrated that the incidence of in-hospital MACE was similar between the patients in whom the LIMA was used for a retrograde approach and the patients in whom a non-LIMA conduit was used for retrograde crossing (5% vs 6%, respectively; P>.99).21
In our study, success rates were high and generally comparable with what has been reported for non-LMCA CTO interventions.3 All 5 patients in the case series published by Flores-Umanzor10 had a successful intervention, and only 1 patient died during the 5-year follow-up period; this was from a non-cardiovascular cause and the other patients remained symptom free.
Study limitations. Our study has limitations. First, we did not have long-term follow-up of the study participants. Second, our study was retrospective and observational in design, without core laboratory assessment of the study angiograms or independent clinical event adjudication. Third, study procedures were performed in dedicated, high-volume CTO centers by experienced operators, limiting the extrapolation to less-experienced operators and lower-volume centers.
LMCA-CTO-PCI is infrequently performed and is mainly used in patients with prior CABG, but appears to be associated with favorable acute procedural outcomes.
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From the 1Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Abbott Northwestern Hospital, Minneapolis, Minnesota; 2Columbia University, New York, New York; 3Henry Ford Hospital, Detroit, Michigan; 4Beth Israel Deaconess Medical Center, Boston, Massachusetts; 5VA San Diego Healthcare System and University of California San Diego, La Jolla, California; 6Baylor Heart and Vascular Hospital, Dallas, Texas; 7Medical Center of the Rockies, Loveland, Colorado; 8Cleveland Clinic, Cleveland, Ohio; 9Wellstar Health System, Marietta, Georgia; 10Maimonides Medical Center, Brooklyn, New York; 11St. George University Hospital Center, Beirut, Lebanon; 12University of Szeged, Division of Invasive Cardiology, Second Department of Internal Medicine and Cardiology Center, Szeged, Hungary; and 13VA North Texas Health Care System and University of Texas Southwestern Medical Center, Dallas, Texas.
Funding: The PROGRESS-CTO registry has received support from the Abbott Northwestern Hospital Foundation, Minneapolis, Minnesota.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Abi Rafeh reports proctor and speaker honoraria from Boston Scientific and Abbott Vascular. Dr Ali reports grant funds and personal fees from Abbott, Medtronic, and Cardiovascular Systems, Inc; personal fees from Boston Scientific and Cardinal Health; unclassified income from Shockwave Medical. Dr Banerjee reports research grants from Gilead and the Medicines Company; consultant/speaker honoraria from Covidien and Medtronic; ownership in MDCare Global (spouse); intellectual property in HygeiaTel. Dr Basir reports grants/personal fees from Abiomed and Chiesi; personal fees from Cardiovascular Systems, Inc, and Zoll. Dr Brilakis reports consulting/speaker honoraria from Abbott Vascular, American Heart Association (associate editor Circulation), Amgen, Boston Scientific, Cardiovascular Innovations Foundation (Board of Directors), CSI, Elsevier, GE Healthcare, and Medtronic; research support from Siemens, Regeneron, and Osprey; shareholder in MHI Ventures; Board of Trustees for the Society of Cardiovascular Angiography and Interventions. Dr Choi reports non-financial support from Abbott Vascular; personal fees from Medtronic and Boston Scientific. Dr Karmpaliotis reports speaker honoraria from Abbott Vascular, Boston Scientific, Medtronic, and Vascular Solutions. Dr Khatri reports grant funds from Asahi Intecc; personal fees from Abbott Vascular and Boston Scientific. Dr Kirtane reports institutional funding to Columbia University and/or Cardiovascular Research Foundation from Abbott Vascular, Abiomed, Boston Scientific, CathWorks, Medtronic, Siemens, Philips, ReCor Medical, and Spectranetics. Dr Lembo reports personal fees from Abbott Vascular, Abiomed, Boston Scientific, and Medtronic. Dr Mahmud reports speaker’s bureau income from Medtronic. Dr Patel reports personal fees from Abbott Vascular, Boston Scientific, and Medtronic. Dr Rangan reports institutional research grant from Spectranetics and InfraRedx. Dr Yeh reports grant support from Abbott Vascular and Boston Scientific; personal fees from Abbott Vascular, Boston Scientific, Asahi Intecc, and Medtronic.
The authors report that patient consent was provided for publication of the images used herein.
Manuscript submitted February 2, 2019, accepted February 11, 2019.
Address for correspondence: Emmanouil S. Brilakis, MD, PhD, Minneapolis Heart Institute, 920 East 28th Street #300, Minneapolis, MN 55407. Email: firstname.lastname@example.org