Summary
Aim
To assess the feasibility and safety of a hybrid myocardial revascularization strategy combining “exclusive arterial” conventional coronary artery bypass grafting (CABG) followed by early drug-eluting stent (DES) implantation in multivessel coronary artery disease (CAD).
Methods
Eighteen consecutive patients with multivessel CAD were enrolled prospectively. Within 48 hours of CABG using left internal mammary artery (IMA) to left anterior descending (LAD) coronary artery with or without right IMA to non-LAD vessel in an open chest approach, DESs were implanted systematically in an additional vessel after a clopidogrel 300-mg preloading dose. This group was compared with 18 matched patients who underwent standard CABG alone using left IMA to LAD and at least one additional graft.
Results
Baseline clinical characteristics were similar in both groups. There were 46 grafts in the CABG group and 28 in the hybrid group. In the hybrid group, 27.8% of patients were treated off-pump versus none in the CABG group; a median of 2 (interquartile range: 1–2) stents was implanted per patient. The hybrid procedure was associated with shorter durations of cardiopulmonary bypass (77 [67–100] min versus 97 [90–105] min, P = 0.049). Major bleeding rates were higher in the CABG group, but the difference was not statistically significant (44.4% versus 11.1%, P = 0.06). Re-intervention for bleeding was not needed in either group. One (5.6%) myocardial infarction occurred in hospital in each group following CABG. At 1 year, the cumulative rates of major adverse cardiac events (death, myocardial infarction, target vessel revascularization) were similar (11.2% in hybrid group versus 5.6% in CABG group, P = 0.99). One death occurred in the CABG group and one target vessel revascularization in the hybrid group.
Conclusion
A hybrid revascularization strategy, combining conventional CABG with exclusive arterial conduits followed by early DES implantation, is feasible. One-year event rates compare favourably to those with traditional CABG alone.
Résumé
Objectifs
Évaluer la faisabilité et la sécurité d’une stratégie de revascularisation myocardique hybride combinant pontage coronaire (PC) « exclusivement artériel », suivi de l’implantation précoce d’un ou de plusieurs stents actifs (SA) chez des patients présentant une atteinte multitronculaire.
Méthodes
Dix-huit patients présentant une maladie coronaire multitronculaire ont été inclus de manière prospective. Dans les 48 heures suivant la réalisation d’un PC à thorax ouvert (artère mammaire interne (AMI) gauche greffée sur l’artère interventriculaire antérieure [IVA] ± AMI droite sur un autre vaisseau que l’IVA), au moins un SA était systématiquement implanté sur une des lésions non pontées après une dose de charge de 300 mg de clopidogrel. Ce groupe était comparé à 18 patients appariés ayant bénéficié uniquement d’un PC traditionnel associant AMI gauche greffée sur l’IVA et au moins une veine durant la même période.
Résultats
Les caractéristiques cliniques de base étaient similaires dans les deux groupes. Il y avait 46 greffons dans le groupe PC seul et 28 greffons dans le groupe hybride, avec une médiane de 2 [25–75 e percentile : 1–2] stents implantés par patient. Dans le groupe hybride, 27,8 % des patients étaient traités à cœur battant, alors qu’aucun patient ne l’était dans le groupe PC seul. Ainsi pour les patients opérés sous circulation extracorporelle (CEC), la procédure hybride était associée à des durées plus courtes de CEC (77 [67–100] minutes versus 97 [90–105] minutes ; p = 0,049). Le taux de saignement majeur avait tendance à être plus élevé dans le groupe PC seul (44,4 % versus 11,1 % ; p = 0,06). Il n’y avait pas de réintervention pour cause de saignements dans les deux groupes. Un (5,6 %) infarctus du myocarde est survenu en milieu intrahospitalier dans le groupe PC seul. Aucune complication de l’angioplastie n’était constatée dans le groupe hybride. À un an, le taux cumulé d’évènement cardiaque indésirable défini comme l’association de décès, infarctus du myocarde et revascularisation du vaisseau cible était similaire dans les deux groupes (11,2 % dans le groupe hybride versus 5,6 % dans le groupe PC seul ; p = 0,99). Un décès était constaté dans le groupe PC seule et une revascularisation du vaisseau cible dans le groupe hybride.
Conclusion
Une stratégie de revascularisation hybride combinant PC exclusivement artériel suivi de l’implantation précoce de SA apparaît comme faisable et semble être, à un an, au moins aussi sûre et efficace qu’une revascularisation par PC seul.
Introduction
Coronary artery bypass graft (CABG) surgery, involving grafting of the left internal mammary artery (IMA) to the left anterior descending (LAD) artery with additional vein graft (VG), remains the standard technique for treatment of multivessel coronary artery disease (CAD) . The left IMA grafted to the LAD provides the best long-term patency and survival benefit over percutaneous coronary intervention (PCI) for treating LAD stenosis . As recent studies have reported a high rate of VG occlusion, which can reach >25% within 12–18 months , the long-term outcome of VGs has been questioned. The advent of PCI with drug-eluting stents (DES) has resulted in a reduction in restenosis rates and the need for repeat revascularization versus PCI with bare-metal stents, with a 12-month restenosis rate making this revascularization technique an attractive option compared with VGs . Both CABG and PCI have their limitations and advantages, but rather than viewing them as mutually exclusive, there may be a role for their combined use in specific patient populations.
Recent studies have reported the feasibility and safety of a simultaneous hybrid coronary revascularization technique combining CABG with left IMA to LAD and DES implantation for treating multivessel CAD , but owing to logistical and practical concerns, few teams have been able to provide it. Given these considerations, a two-stage revascularization process combining CABG and DES implantation could offer a more realistic alternative. Several teams have reported the feasibility of performing CABG followed by PCI ( Table 1 ). However, these studies used either a minimally invasive direct coronary artery bypass (MIDCAB) or robotically enhanced-MIDCAB (RE-MIDCAB). Besides sizeable logistical issues making these techniques available for only a restricted number of teams, this minimally invasive surgery is limited mostly to revascularization of the LAD territory, as the circumflex and right coronary arteries (RCAs) are less accessible. Using a hybrid approach involves revascularization of all of the other vessels by PCI, but even in the “DES era”, PCI remains limited to suitable anatomical lesions.
| Lead author (year) | n b | Surgical procedure | Delay between CABG and PCI | Delay between CABG and PCI (range) | DES use |
|---|---|---|---|---|---|
| Lloyd et al. (1999) | 14 | MIDCAB | NR | From 1–3 days | No |
| Wittwer et al. (2000) | 35 | MIDCAB | 7 days (median) | NR | No |
| Stahl et al. (2002) | 35 | RE-MIDCAB | 16 days (mean) | From 18 hours to 3 months | No |
| Riess et al. (2002) | 53 | MIDCAB | 5 days (median) | From 2–7 days | No |
| Davidavicius et al. (2005) | 6 | RE-MIDCAB | NR | In-hospital to 160 days | Yes, 1 patient only |
| Katz et al. (2006) | 12 | RE-MIDCAB | 16 days (mean) | From 2–60 days | Yes, 63% of patients |
| Holzhey et al. (2008) | 59 | RE-MIDCAB or MIDCAB | NR | From 2–45 days | Yes |
| Gao et al. (2009) | 10 | RE-MIDCAB | NR | From 4–5 days | Yes, 20% of patients |
b Number of patients who underwent the two-stage hybrid procedure.
The use of the right IMA in addition to left IMA grafting with a conventional open chest approach has been shown to provide long-term benefits when compared with revascularization using a single left IMA and VG . Thus a hybrid revascularization combining “exclusive arterial” CABG with DES implantation – the most successful applications of surgical and percutaneous techniques in patients with multivessel CAD – appears very attractive. Besides avoiding non-arterial grafts, this hybrid approach could be helpful in cases of poor or non-harvestable grafts as well as for reducing the duration of surgery.
Here, we report the feasibility, safety and outcomes of a hybrid revascularization strategy combining conventional CABG with exclusive arterial conduits (left IMA to LAD with or without right IMA to non-LAD vessel) with a conventional open chest approach, followed by early DES implantation, in patients with multivessel CAD. This revascularization strategy was compared with a conventional approach using CAGB alone.
Methods
Study population
Between October 2006 and January 2008, 18 patients with multivessel CAD were enrolled prospectively to undergo myocardial revascularization. The hybrid strategy associated CABG with exclusive arterial conduits (left IMA to LAD with or without right IMA to non-LAD vessel) followed, within 48 hours, by DES implantation in an additional vessel.
Inclusion criteria for hybrid revascularization were the presence of multivessel CAD, a >70% LAD obstruction judged suitable for surgery, and the presence of a non-LAD lesion(s) suitable for either right IMA graft and PCI, or PCI only. Patients not suitable for treatment with dual antiplatelet therapy (aspirin plus clopidogrel) for at least 1 year, those taking an oral anticoagulant, and patients scheduled for surgery within 1 year after PCI were excluded. All cases were validated by both the surgeon and the interventional cardiologist.
Using a prospective case-controlled study design, a parallel control group of 18 patients who underwent conventional CABG alone (left IMA to LAD and additional grafts for non-LAD vessels: VG for double bypass and VG plus right IMA for triple bypass) during the same period of time was matched, according to sex, age, diabetes, clinical presentation and number of treated vessels.
All patients provided informed consent to be enrolled in the study and to anonymous data analysis. The study was approved by and registered with the local ethics committee.
Surgical procedure
Pharmacological management
All patients were given oral antiplatelet therapy with aspirin 160 mg/day before and after CABG. Patients taking clopidogrel stopped this treatment 5 days before the CABG procedure. Preoperative statin therapy was given systematically. Systemic treatment with unfractionated heparin was given after internal mammary harvesting: 300 U/kg for on-pump CABG surgery and 100 U/kg for off-pump CABG. Heparin was antagonized with protamine sulphate at a ratio of 1:1 upon completion of distal and proximal coronary anastomosis or weaning of the cardiopulmonary bypass (CPB) in both groups.
Surgery
Median sternotomy was performed in all patients. The left IMA was harvested, together with additional graft material (right IMA and/or VG). The decision to use either on-pump or off-pump CABG was left to the discretion of the surgeon.
On-pump coronary artery bypass graft surgery
Intermittent cold blood hyperkaliemic cardioplegia and moderate hypothermia (33 °C) were used in all CABG patients. During CPB, the mean arterial pressure was allowed to vary between 60 and 90 mmHg. Tight glycaemic control (<1.5 g) was observed until discharge.
Off-pump coronary artery bypass graft surgery
Stabilization of the beating heart was established with the Octopus III ® (Medtronic Inc., Minneapolis, MN). Heart displacement into varied grafting positions was aided by the use of deep pericardial retraction sutures facilitating exposure of lateral and posterior walls. The Trendelenburg’s position was used and the table tilted when necessary. No apical suction devices were used to assist immobilization. Intracoronary shunts were not used in this study.
Percutaneous coronary intervention procedure for hybrid revascularization
Coronary stenting was performed using conventional techniques, within 48 hours of CABG. The interventional strategy was left to the discretion of the operator. In all cases, a femoral approach was employed. All patients underwent postoperative angiography to demonstrate patency of the grafts at the time of the PCI. Intraprocedural anticoagulation was ensured using unfractionated heparin with a bolus of 40–50 U/kg. Glycoprotein IIb/IIIa inhibitors were not used. All patients received aspirin 160 mg/day before the procedure and continued this regimen indefinitely. All patients received a clopidogrel loading dose of 300 mg, 6 hours before PCI, followed by a maintenance dose of 75 mg/day after PCI for at least 1 year. The sheath was removed at the end of the procedure using manual compression or an arterial closure device.
Follow-up and definition endpoints
All patients attended routine clinical follow-up and were contacted by a nurse to assess long-term clinical outcome. The primary endpoint was the 1-year rate of major adverse cardiac events (MACE) defined as the composite of death, myocardial infarction (MI) and target vessel revascularization (TVR). Death was defined as all-cause mortality. MI was defined as creatinine kinase (CK) ≥5 times the upper limit of normal (ULN) within 24 hours after CABG, CK ≥3 times the ULN within 24 hours after PCI, and thereafter as CK ≥2 times the ULN and/or ischaemic electrocardiographic changes including ST elevation ≥1 mm or new Q-waves. TVR was characterized by ischaemia-driven percutaneous or surgical revascularization of the treated vessel. Definite stent thrombosis was considered as defined by the Academic Research Consortium . Procedural success was defined as attainment of both thrombolysis in myocardial infarction (TIMI) flow grade 3 and a residual stenosis <30%. Major bleeding was defined as the TIMI study group definition, i.e. a decrease in haematocrit of ≥15% and/or the occurrence of intracranial bleeding . CABG-related bleeding was included in the definition.
SYNTAX score calculation
The SYNTAX score is an angiographic tool that allows clinicians to grade the complexity of CAD: the higher the score, the more complex the disease. The SYNTAX score for each patient was calculated retrospectively by two interventional cardiologists blinded to the group assignment. All coronary lesions with a diameter stenosis of ≥50% in vessels of ≥1.5 mm were scored according to the SYNTAX score algorithm, which has been described elsewhere and is available on the SYNTAX score website ( www.syntaxscore.com ) .
Statistical analysis
Continuous variables are shown as medians (25–75th percentiles). Categorical variables are expressed as percentages. The Mann-Whitney test was used to compare continuous variables and the Chi 2 test or Fisher’s exact test to compare categorical variables. Statistical significance was assumed at P < 0.05. All analyses were conducted using SPSS 11.0 software (SPSS Inc., Chicago, IL, USA).
Results
Patients’ characteristics
Patients’ baseline characteristics are shown in Table 2 . There were no differences in the baseline characteristics of patients in the CABG group and those in the hybrid group. Sixteen (88.9%) patients in both groups had three-vessel CAD.
| Variable | CABG group ( n = 18) | Hybrid group ( n = 18) | P |
|---|---|---|---|
| Demographic | |||
| Age (years) | 60 (53–68) | 62 (55–70) | 0.36 |
| Female sex | 4 (22.2) | 4 (22.2) | 1.00 |
| Cardiovascular risk factor | |||
| Diabetes mellitus a | 7 (38.9) | 8 (44.5) | 0.74 |
| Hypertension b | 14 (77.8) | 12 (66.7) | 0.71 |
| History of smoking | 7 (38.9) | 8 (44.4) | 0.36 |
| Body mass index (kg/m 2 ) | 27 (24–31) | 28 (23–31) | 0.91 |
| Hypercholesterolaemia c | 12 (66.7) | 15 (83.3) | 0.44 |
| Chronic renal failure d | 1 (5.6) | 0 (0%) | 1.00 |
| Cardiovascular history | |||
| Stroke | 0 (0) | 2 (11.1) | 0.49 |
| Myocardial infarction | 3 (16.7) | 5 (27.8) | 0.69 |
| CABG | 0 (0.0) | 0 (0.0) | – |
| Peripheral vascular disease e | 3 (16.7) | 5 (27.8) | 0.69 |
| Indication for PCI | |||
| Stable angina | 5 (27.8) | 8 (44.4) | 0.30 |
| Acute coronary syndrome | 13 (72.2) | 10 (55.6) | 0.30 |
| Left ventricular ejection fraction (%) | 60 (55–65) | 60 (54–65) | 0.84 |
| Three-vessel disease | 16 (88.9) | 16 (88.9) | 1.00 |
| Baseline haemoglobin | 13.6 (12.0–15.0) | 12.7 (11.8–13.9) | 0.17 |
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