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ORIGINAL ARTICLE |
Department of Cardiac Surgery, Punjab Institute of Cardiology, Lahore, Pakistan
1 Department of Cardiology, Punjab Institute of Cardiology Lahore, Pakistan
2 Department of Research and CME Punjab Institute of Cardiology, Lahore, Pakistan
Raja Parvez Akhtar, FRCS, Tel: +92 3008465515, Fax: +92 429200028, Email: rajapakhtar{at}gmail.com, Cardiac Surgery Department, Punjab Institute of Cardiology, Lahore, Pakistan.
ABSTRACT
Chronic total occlusion of the left main stem coronary artery is rare. This retrospective study was conducted to evaluate outcomes of coronary artery bypass grafting between June 1998 and June 2008 in patients with chronic left main stem total occlusion. There were 17 (0.025%) cases detected in 67,082 coronary angiograms. The 14 men and 3 women had a mean age of 55.32 ± 9.2 years. Risk factors included diabetes in 8, hypertension in 6, and smoking in 6. Of 54 grafts applied, 15 were arterial and 39 were venous; 14 patients had 3-vessel disease, and 3 had 4-vessel disease. Three patients required intraaortic balloon counterpulsation perioperatively. The mean intensive care unit stay was 2.1 ± 1.2 days, and hospital stay was 7.1 ± 1.5 days. Postoperatively, one patient suffered myocardial infarction, another had a transient ischemic attack with spontaneous recovery, and 2 developed atrial fibrillation. There was no operative or hospital death. Surgical revascularization is considered appropriate treatment for chronic total occlusion of the left main stem.
Key Words: Coronary artery disease • Left main stem disease • Chronic total occlusion • Coronary artery bypass graftin • Percutaneous coronary intervention
INTRODUCTION
Chronic total occlusion of the left main stem (LMS) is rare in patients with coronary atherosclerotic disease, with a prevalence of 0.04% to 0.4%.1–3 Coronary artery bypass grafting (CABG) is the treatment of choice for LMS disease, especially in cases of total occlusion.4–8 Total LMS occlusion is characterized by no antegrade blood flow to the left anterior descending (LAD) and left circumflex (LCx) arteries.9,10 Total occlusion can be either acute or chronic.11 Acute total occlusion follows an event such as myocardial infarction (MI) or a sudden change in the angina pattern, with electrocardiographic (ECG) changes consistent with the site of occlusion. Chronic occlusion is asymptomatic, with a duration of >3 months.11 LMS stenosis is usually associated with significant disease elsewhere in the coronary tree, which may lead to symptoms before complete obstruction occurs.1,2 LMS stenosis occurs as an isolated lesion in 6%–9% of patients undergoing coronary angiography, whereas multivessel disease is found in 70%–80%. Revascularization for LMS stenosis should be accomplished by CABG rather than stenting.7 Percutaneous coronary interventions (PCI) have been performed in cases of acute total occlusion of the LMS.9,11,12 We describe our 10-year experience in patients with chronic LMS total occlusion.
PATIENTS AND METHODS
This retrospective study was conducted in patients who were treated between June 1998 and June 2008. Of 67,082 coronary angiographies performed during this period, 17 (0.025%) detected chronic total occlusion of the LMS. The characteristics of these 17 patients are given in Table 1
. None had a history of transient ischemic attack or cerebrovascular accident; however, carotid Doppler examination revealed 3 patients had 50% stenoses of the right common carotid artery, 1 had 50% stenosis in the left internal carotid artery, and 2 had mild intimal thickening of both carotids. In all patients, the LAD filled retrogradely from the right coronary artery (RCA; Figure 1A,B). In 15 patients, the target vessel was of good quality, 2 had diffuse LAD disease. The LCx filled retrogradely from the RCA in 12 patients, and 12 had >70% stenosis of the RCA and its branches.
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All patients were followed up daily until discharge, and weekly for 30 days postoperatively. All complications were recorded. Hospital mortality was defined as death occurring within 30 days postoperatively. Perioperative MI was defined as persistent ECG changes such as new Q waves, loss of R-wave progression, new intraventricular conduction defects, elevation of creatinine kinase-MB or cardiac troponin, or new echocardiographic evidence of a wall motion abnormality occurring within the first 48 h postoperatively.13 Other hospital complications included postoperative atrial fibrillation, renal failure, cerebrovascular accident, low output syndrome (inotropic support >24 h or new placement of an intraaortic balloon pump to wean off cardiopulmonary bypass or maintain systolic blood pressure >100 mm Hg), and wound infection.13 No postoperative angiography for evaluation of graft patency was offered to these patients.
Statistical analysis was performed using SPSS version 14.0 software for Windows (SPSS, Inc., Chicago, IL, USA). Categorical variables are expressed as frequencies and percentages, while continuous variables are expressed as mean and standard deviation. Hospital mortality and complications are expressed as frequencies and percentages.
RESULTS
The mean aortic crossclamp time was 32.3 ± 9.9 min, and mean cardiopulmonary bypass time was 69 ± 17.1 min. The LIMA was anastomosed to LAD in all except 2 patients who received saphenous vein grafts: one due to advanced age and chronic obstructive pulmonary disease; the other became unstable at sternotomy so cardiopulmonary bypass was instituted and a vein graft was immediately applied to the LAD. The angiographic findings and distribution of grafts are shown in Table 2. Three (17.6%) patients required intraaortic balloon counterpulsation: it was instituted preoperatively due to unstable hemodynamics in 2, and immediately after surgery due to difficulty in weaning from bypass in the patient who underwent LAD endarterectomy. The mean intensive care unit stay was 2.1 ± 1.2 days, and mean hospital stay was 7.1 ± 1.5 days. Two patients had superficial sternal wound infections, 2 had transient atrial fibrillation during the hospital stay, and the patient who underwent endarterectomy had ECG changes consistent with perioperative MI in the LAD territory. One patient with normal carotid arteries had a transient ischemic attack with spontaneous recovery and no residual neurological deficit. There was no operative or hospital death. All patients were discharged on antiplatelet and statin therapy, with no recurrence of symptoms at 30 days, 3, and 6 months postoperatively. None needed any further intervention, and they were referred back to their cardiologists 6 months after the operation.
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Chronic total LMS occlusion is a rare presentation of atherosclerotic disease. CABG is the treatment of choice because crossing the occlusion with a wire has a limited success rate of 40%–81% and a higher incidence of restenosis.3 We observed a 0.025% incidence of chronic total LMS occlusion, which is marginally lower than that in previous series. Initially, we performed angiography in hemodynamically stable patients, but now we undertake angiography and primary PCI of hemodynamically unstable patients in our institute. This could be the reason for no cases of acute total occlusion, as well as the lower incidence of chronic total occlusion in our study.
Ward and colleagues2 described 5 patients with a long history of angina and total LMS occlusion, and highlighted the importance of collateral formation as well as the superiority of CABG over medical therapy. They also observed postoperative improvement in LV function, which we found in 3 patients in our series. Yip and colleagues14 carried out primary PCI in 8 patients with total and 10 with subtotal LMS occlusion. There was a 72.2% procedural success rate; 4 patients underwent CABG, 6 died in hospital, and 2 died after discharge. The 10 survivors had more intercoronary collaterals, a dominant RCA, and incomplete LMS occlusion. Acute total LMS occlusion generally presents as pulmonary edema, cardiogenic shock, or sudden death. In our opinion, CABG is the preferred treatment for chronic total LMS occlusion, whereas in acute LMS occlusion, it is one of the therapeutic options along with primary angioplasty which is preferred if the patient has good collaterals and incomplete occlusion. Bare metal stenting for LMS occlusion has a 1-year mortality rate of 3%–28% and a restenosis rate of 20%.15 The restenosis rate of drug-eluting stents is 10%. In view of the high restenosis and mortality rates with PCI in this condition, it is suggested that PCI should only be used as a last resort in patients deemed unsuitable for CABG because of prohibitive comorbidities.15
A recent trial studied 1,800 patients with left main or 3-vessel coronary artery disease randomly assigned to undergo CABG or PCI with drug-eluting stents.16 The CABG group had more severe lesions, including total occlusion, bifurcation lesions, lesions >20 mm in length, and heavy calcification, than the PCI group; however, patients treated by PCI were more likely to reach the primary end-points of death from any cause, stroke, MI, or repeat revascularization within 12 months. Comparing secondary end-points, the 2 treatment groups had similar rates of death from any cause, stroke, or MI.16 Patients undergoing PCI were more likely to require repeat revascularization but less likely to suffer stroke than those undergoing CABG. Hence it was concluded that CABG was preferred for patients with 3-vessel or left main coronary artery disease.
Ipek and colleagues5 studied 7 patients with chronic total LMS occlusion with reference to myocardial preservation options, 3 also had severe RCA lesions, prior MI, and significantly depressed LV function. Five patients had on-pump CABG and 2 had off-pump grafting; all received alternating antegrade/retrograde cardioplegia for myocardial preservation. Postoperative low cardiac output occurred in only one patient who had off-pump surgery, and there was no operative or early mortality. In our study, 12 patients had>70% stenosis in the RCA and its branches, which were successfully grafted with saphenous vein. Intermittent crossclamping and fibrillatory arrest was opted for in 10 patients, while 7 had blood cardioplegia; there was no difference in postoperative events in our 2 groups. We agree with Ipek and colleagues5 on the strategy of revascularization of a totally occluded vessel prior to that giving off collaterals to it, and we also feel that antegrade blood cardioplegia alone is an effective and safe means of myocardial preservation. Only 3 of our 12 patients with RCA disease had depressed LV function, which is lower than in previous reports, possibly because the disease was in distal RCA branches. As chronic total LMS occlusion is a progressive lesion, and patients have a calcified proximal LMS, we do not consider that they are appropriate candidates for surgical angioplasty or reconstruction of the left coronary ostium and left main stem, although it is a good option for isolated ostial LMS stenosis with a normal distal left system.17 We agree with Ipek and colleagues5 that priority should be given to retrograde filling vessels of the left system, followed by grafts to the obtuse marginal and diagonal branches, and finally the RCA if diseased. Sugishita and colleagues4 studied 3 patients with chronic total LMS occlusion (2 had atherosclerotic disease, 1 had Kawasaki disease) who underwent successful CABG; all had a dominant RCA with good collaterals to the left system, which are necessary for patients to survive chronic total LMS occlusion with preserved LV function; 2 were followed up for more 10 years after surgery. In our study, all patients had a dominant RCA, but 12 had RCA stenosis requiring bypass grafting. Topaz and colleagues18 emphasized the importance of collateral vessels in preserving LV function in 13 cases of chronic total LMS occlusion. We agree as 3 of our 4 patients with proximal RCA disease and poor collaterals had depressed LV function, but we have no explanation for preserved LV function the 4th patient. Shen and colleagues19 found that RCA disease was associated with decreased survival after CABG in 23 patients with chronic total LMS occlusion, whereas we had no deaths among the 12 patients with RCA disease.
We concluded that CABG is a good treatment option for chronic total LMS occlusion, and either intermittent crossclamping and fibrillation or antegrade blood cardioplegia can be used safely.
ACKNOWLEDGMENTS
The authors thank the Residents of the Cardiac Surgery Department, Punjab Institute of Cardiology Lahore. Miss Alliya Akhtar’s help in the compilation of this manuscript is also highly appreciated. We are also grateful to Mr Raza Qadeer, librarian at Shaukat Khanum Cancer Research Hospital, Lahore-Pakistan for his help in researching the references.
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:472-476
© 2009 by SAGE Publications
DOI: 10.1177/0218492309343857
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