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Abstract
Background— The presence of a lumen narrowing at the ostium and the body of an unprotected left main coronary artery but does not require bifurcation treatment is a class I indication of surgical revascularization.
Methods and Results— A total of 147 consecutive patients who had a stenosis in the ostium and/or the midshaft of an unprotected left main coronary artery (treatment of the bifurcation not required) and were electively treated with percutaneous coronary intervention and sirolimus-eluting stents (n=107) or paclitaxel-eluting stents (n=40) in 5 centres were included in this registry. In 72 patients (almost 50%), intravascular ultrasound guidance was performed. Procedural success was achieved in 99% of the patients; in 1 patient with stenosis in the left main coronary artery ostium, a >30% residual stenosis persisted at the end of the procedure, and the patient was referred for coronary artery bypass graft surgery. During hospitalization, no patients experienced a Q-wave myocardial infarction or died. One patient died 19 days after the procedure because of pulmonary infection. At long-term clinical follow-up (886±308 days), 5 patients had died; 7 patients had target vessel revascularization (5 repeat percutaneous coronary interventions and 2 coronary artery bypass graft surgeries), and of these only 1 patient had a target lesion revascularization. Angiographic follow-up was performed in 106 patients (72%) with a late loss of −0.01 mm. Restenosis in the left main trunk occurred only in 1 patient (0.9%).
Conclusions— Percutaneous coronary intervention with sirolimus-eluting stents or paclitaxel-eluting stents implantation in nonbifurcation left main coronary artery lesions appears safe with a long-term major adverse clinical event rate of 7.4% and a restenosis rate of 0.9%.
Received January 23, 2007; accepted May 8, 2007.
The presence of a lumen that narrows at the ostium and mid-shaft of the left main coronary artery (LMCA) but does not require bifurcation treatment is considered a class I indication of surgical revascularization.1–3 Registry data of percutaneous coronary interventions (PCI) with use of drug-eluting stents (DES) in unprotected LMCA lesions showed that this is a feasible and safe approach.4–9 In particular, low and encouraging event rates were observed in patients with nonbifurcation LMCA stenosis.4,5,7–11 To date, few data are available on the outcome of this specific patient subset when treated with DES. The aim of the present registry is therefore to evaluate the treatment of nonbifurcation LMCA stenosis with PCI and DES implantation (either sirolimus or paclitaxel) at long-term clinical follow-up.
Methods
The present study included all consecutive patients who had a stenosis in the ostium and/or the mid-shaft of an unprotected LMCA (treatment of the bifurcation not required) electively treated with PCI and sirolimus-eluting stents (Cypher, Cordis, Johnson & Johnson, Warren, N.J.) or paclitaxel-eluting stents (Taxus, Boston Scientific, Natick, Mass.) in 5 centers (San Raffaele Hospital and EMO Centro Cuore Columbus in Milan, San Giovanni Battista Hospital in Turin, Italy; Erasmus Medical Center-Thoraxcenter, the Netherlands; Asan Medical Center, Korea). Patients with ST or non-ST-elevation myocardial infarctions were excluded from the analysis.
The decision to perform PCI instead of surgery was considered when 1 of these 2 conditions was present: (1) suitable anatomy for stenting and preference by patient and by referent physician for a percutaneous approach or (2) suitable anatomy for stenting and disincentive for surgery defined as a EuroSCORE (European system for cardiac operative risk evaluation) ≥6 and/or Parsonnet score ≥13 and/or prior bypass surgery with failure of all conduits (n=2).
Coronary angioplasty and DES implantation were performed according to the practice of complete coverage of the diseased segment.12–15 Our stenting technique in ostium and/or shaft unprotected LMCA has been previously described.16 At the start of the procedure, a bolus of unfractionated heparin (100 IU/kg) was administered to achieve an activated clotting time >250 seconds. Glycoprotein IIb/IIIa inhibitors were administered at the discretion of the operator. Clinical follow-up was scheduled for all patients at 1, 6, 12, and 24 months by office visit or direct telephone call to the patients. Patients eligible for longer clinical follow-up were contacted at 36 and 48 months.
Dual antiplatelet therapy (aspirin 100 mg/d and 75 mg/d clopidogrel or 250 mg ticlopidine twice daily) was administrated according to local practice (for at least 6 months after the procedure in Rotterdam and Turin and 12 months in Milan and Seoul). All patients were advised to maintain lifelong use of aspirin (100 mg/d).
Angiographic follow-up was scheduled between 4 and 9 months or earlier if noninvasive evaluation or clinical presentation suggested the presence of ischemia.
Definitions
The events analyzed during hospital stay and at long-term clinical follow were death, coronary artery bypass grafting (CABG), myocardial infarction (MI), restenosis, target lesion revascularization (TLR), and target vessel revascularization (TVR). Procedural success was defined as revascularization in the target lesion with <20% residual stenosis according to angiography and with the patient released from the hospital free of any of these events: death, MI, or CABG.
Deaths were classified as either cardiac or noncardiac. Death of unknown cause was adjudicated as cardiac. Non-Q-wave MI was defined as elevation of serum creatine kinase MB isoenzyme that was 3 times the upper limit of normal in the absence of pathological Q waves.
Restenosis was defined as >50% luminal narrowing at the segment site (stent and 5 mm proximal and distal) demonstrated at the follow-up angiographies, regardless of clinical symptoms of the patient.
TLR was defined as any revascularization performed on the treated segment; TVR was defined as any reintervention performed on the treated vessel and also included treatment of any segment in left anterior descending and circumflex artery.
Major adverse cardiac events (MACE) were defined as a composite of cardiac death, MI, and TVR.
The Parsonnet score and EuroSCORE were used to stratify the risk of death at 30 days.17,18 The patients were stratified as high risk in the presence of a EuroSCORE ≥6 and/or Parsonnet score ≥13 and/or prior bypass surgery with failure of all conduits.
Statistical Analysis
Continuous data were reported as means or median and interquartile range as appropriate. Event-free survival during follow-up at long term clinical follow-up (886±308 days) was evaluated according to the Kaplan-Meier method. SAS version 8.2 (SAS Institute, Cary, NC) was used for the analysis.
The authors had full access to and take full responsibility for the integrity of the data. All authors have read and agree to the manuscript as written.
Results
Baseline clinical, lesion, and procedural characteristics are summarized respectively in Tables 1 and 2⇓. Quantitative coronary angiography measurements are reported in Table 3.
TABLE 1. Clinical Characteristics of the Study Population (n=147 Patients)
TABLE 2. Lesion and Procedural Characteristics of the Study Population (n=147 Patients)
TABLE 3. Quantitative Coronary Angiography Measurements
From a total population of 790 patients with unprotected LMCA electively treated in our centers with PCI and DES, 147 patients (18.6%) had ostial and/or shaft left main disease. Twenty-nine patients (19.7%) had diabetes and 64 patients (43.5%) had unstable angina. Mean age was 62.6±12.3 years and left ventricular ejection fraction 55.2±11.3%. Median and interquartile ranges of EuroSCORE and Parsonnet scores were respectively 4 (1 to 7) and 5 (2 to 11.5). Sixty patients (40.8%) were treated because of a EuroSCORE ≥6 and/or Parsonnet score ≥13 (n=58) and/or prior bypass surgery with failure of all conduits (n=2); 87 patients (59.2%) because of patients and referring physician’s preference. In 77 patients the stenosis was located at the ostium, in 41 patients the stenosis was located in the mid-shaft, and in 29 patients the stenosis was located both at the ostium and in the mid-shaft of the LMCA. Fifty-one patients (34.7%) had right coronary artery disease; 22 patients had concomitant right coronary artery treatment. The number of treated vessels was 1.53±0.7 and the number of lesions 1.86±1.5; in 39 patients (26%) of the patients left anterior descending or circumflex arteries were also treated during the index procedure. An intraaortic balloon pump was used in 3 patients; 18 patients (12.2%) had elective administration of glycoprotein IIb/IIIa inhibitors. In 72 patients (49%) intravascular ultrasound (IVUS) guidance was performed. Reference vessel diameter of the LMCA was 3.66±0.5 mm. Predilation was performed in 57 patients (38.7%); cutting balloon was used in 11 of these patients. One hundred and seven patients were treated with sirolimus-eluting stents, and 40 patients were treated with paclitaxel-eluting stents. Maximum balloon diameter was 3.7±0.9 mm and maximum pressure 17.0±4.9 atmospheres. Rotational atherectomy was performed in 2 patients; directional atherectomy in none.
Procedural success was achieved in 146 (99%) of the patients; in 1 patient with stenosis at the ostium of LMCA, a residual stenosis >20% persisted despite aggressive dilatation of the stent before and after the procedure.
In-Hospital and Long-Term MACE
In-hospital and long-term clinical outcome are illustrated in Table 4. During hospitalization no patient experienced a Q-wave MI or died. Five patients (3.4%) had a non-Q-wave MI. One patient required elective CABG as a result of an unsuccessful procedure (residual stenosis >20% after stenting). One patient died 19 days after the procedure because of a pulmonary infection. At 886±308 days, 1 patient died of brain tumor, and 4 patients (2.7%) died of unknown causes at 208, 606, 1149, and 1360 days. No cases of angiographically proven stent thrombosis were observed but stent thrombosis could not be excluded in the 4 patients who died of unknown causes. The clinical characteristics of the 4 patients who died of unknown causes are illustrated in Table 5. Seven patients (4.7%) underwent a TVR: 5 repeat PCIs and 2 CABG. In 6 of these 7 patients the intervention was performed on lesions in other coronary segments (left anterior descending and/or circumflex artery). One patient had a TLR because of the occurrence of a restenosis in the shaft of the LMCA. MACE at follow-up occurred in 11 patients (7.4%) (Figure). Angiographic follow-up was performed in 106 patients (73%) with a late loss of −0.01 mm. Restenosis in left main trunk occurred only in 1 patient (0.9%).
TABLE 4. MACE at Hospitalization and at Long-Term Clinical Follow-Up
TABLE 5. Clinical Characteristics of the 4 Patients Who Died of Unknown Causes
Patients who were free of major adverse cardiac events at long-term clinical follow-up. The dashed lines represent the 95% CIs.
Discussion
The main findings of the present study are: (1) DES implantation for ostial and mid-shaft LMCA stenosis that did not require bifurcation treatment appeared to be safe and effective; (2) the MACE rate at 886±308 days was 7.4%; and (3) the restenosis rate in this anatomic subset of patients was 0.9% with a late loss of −0.01 mm.
Current European Society of Cardiology and American Heart Association/American College of Cardiology guidelines consider the presence of a stenosis in the LMCA (if CABG is not eligible) a class IIb or IIa indication of PCI, respectively.2,3 According to these guidelines,3 in cases where CABG is eligible, PCI has a class III indication irrespective of the lesion location. Some retrospective studies that evaluate surgical treatment for this disease reported an in-hospital mortality that varied from 1.7% to 7.0% and a 1-year mortality of 6% to 14%.19–22 Recently, encouraging results have been reported with elective DES implantation in LMCA with a 1-year mortality of 0% to 5%.4,7,23 In these registries, the need for TLR varied from 0% to 14%.4,7,9,23 In a registry in which all patients were ineligible for CABG and distal lesion location was present in 94% of the patients, a TLR rate of 38% (of which 24% were nonclinically driven) was reported.24 Most of the patients included in these series had distal LMCA stenoses that required bifurcation treatment: the frequency of LMCA stenosis at the ostium and/or the shaft that did not involve the distal segment was 6% to 34%.5,7,9,24 The presence of ostial and mid-shaft lesions in the LMCA was associated with a more favorable outcome and a low restenosis rate, which was significantly higher (8% to 17%) for distal left main lesions, especially with the 2-stent techniques.10
No study has been undertaken so far specifically to evaluate PCI with DES in this particular anatomic subset of patients, primarily because of the low frequency of this disease subset. Few data are available on long-term clinical follow-up of patients with unprotected LMCA lesions treated with DES.
Despite the clinical characteristics of the patients (43.5% had unstable angina and almost 40% had a EuroSCORE ≥6 and/or Parsonnet score ≥13), the occurrence of in-hospital MACE, which included non-Q-wave MI (defined as an elevation of serum creatine kinase MB isoenzyme that was 3 times the upper limit of normal), was low (6.0%). These initially favorable outcomes were maintained at a median of 886 days with a MACE rate of 7.4%. No cases of angiographically proven stent thrombosis were observed, but stent thrombosis could not be excluded in the 4 patients (2.7%) who died of unknown causes (all of them had a left ventricular ejection fraction <40%, a EuroSCORE ≥6, and/or a Parsonnet score ≥13). Therefore, in the worst possible scenario we could assume a cumulative thrombosis rate at a mean of 886 days of 2.7% (95% confidence interval [CI], 1 to 7).
Seven patients had a TVR (5 were treated with PCIs; 2 were treated with CABG). Of these, only 1 patient required TLR because of in-Taxus restenosis in the LMCA shaft. Furthermore, the restenosis rate in our multicenter experience was only 0.9% with a late loss of −0.01 mm. This finding is mostly explained by the favorable anatomic location. Nevertheless, an important factor could have been that in almost 50% of our patients IVUS guidance was performed. IVUS guidance in the DES era is still controversial, especially in this particular subset of lesions. Agostoni et al reported in a small series that IVUS guidance, used in 41% of the total 58 patients who underwent the procedures, was not associated with additional clinical benefit with respect to angiographically assisted stent deployment in patients with LMCA stenosis.25 Conversely, the Korean group reported that in the bare-metal stent era, IVUS guidance could optimize the immediate procedural results, and in patients treated with DES and concomitant IVUS guidance, a restenosis rate of 7% (the lowest reported) was observed.7,26 So far, no randomized data that compared PCI with DES implantation versus CABG are available. The Synergy Between Percutaneous Intervention With TAXUS and Cardiac Surgery (SYNTAX) trial is ongoing and will evaluate 710 patients with left main disease randomized to receive either a paclitaxel-eluting stent or CABG. Registry data that compare PCI with DES implantation versus CABG in unprotected LMCA lesions already show encouraging results.27–29
Study Limitations
This is a retrospective multicenter registry. No a priori sample size has been calculated. In addition, no centralized core quantitative coronary angiography laboratory was established. Moreover, the number of patients analyzed is small, primarily because of the low occurrence of this anatomic subset of lesions in the general population. Another limitation is the length of clinical follow-up. No specific attempt was made to extend dual antiplatelet therapy beyond 6 to 12 months, and no detailed information was available on antiplatelet therapy in the patients who had died at follow-up. Furthermore, silent restenosis could not be completely excluded because of the low rate of angiographic follow-up (73%).
Conclusions
In this multicenter registry, the use of DES in nonbifurcation unprotected LMCA stenosis appeared to be safe and effective. Six-month angiographic follow-up showed a restenosis rate of 0.9% with a cumulative cardiac mortality of 2.7% at a median follow-up of 886 days.
Acknowledgments
Disclosures
None.
References
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- Favorable Long-Term Outcome After Drug-Eluting Stent Implantation in Nonbifurcation Lesions That Involve Unprotected Left Main Coronary Artery
