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Interact CardioVasc Thorac Surg 2009;9:990-994. doi:10.1510/icvts.2009.213900 © 2009 European Association of Cardio-Thoracic Surgery
Long-term follow-up after minimal invasive direct coronary artery bypass grafting procedure: a multi-factorial retrospective analysis at 1000 patient–years
a Division of Thoracic and Cardiovascular Surgery, Hannover Medical School, Germany Received 8 June 2009; received in revised form 21 August 2009; accepted 24 August 2009
*Corresponding author. Tel.: +65 67722065; fax: +65 67766475.
We provide a multi-factorial long-term follow-up following minimal invasive direct coronary artery bypass grafting (MIDCABG) to evaluate the long-term efficacy. From 1996 onwards, 390 patients underwent MIDCABG (follow-up: 30.0±11.2 months). We analyzed peri-operative and postoperative complications (<30 days) and we obtained early and late angiography. Cumulative follow-up was 1000 patient-years. Early postoperative mortality was 0.8% and myocardial infarction occurred in 1.3% of all patients. Early postoperative angiography (<30 days) was obtained in 238 patients (66.3%) and revealed patency in 97.5% (232/238) including 211 (88.6%) who had no stenosis, 13 with a <50% stenosis (5.5%) and 8 with a >50% stenosis (3.4%), but a patent graft. Only six patients had a total occlusion (2.5%). In the long-term follow-up (completed 74.6%; 291/390 patients), the overall mortality was 5.8%, whereas only 1.7% died due to cardiac reasons. Myocardial infarction occurred in 3.0%, redo CABG was necessary in 1.3%. Seventy-eight patients had late postoperative angiography (>30 days) of those 93.6% (n=73) had a patent graft: 58 had no stenosis (74.4%), 4 had a <50% stenosis (5.1%) and 11 had a >50% stenosis (14.1%), but a patent graft. Only in five patients (6.4%) the anastomosis was occluded. MIDCABG is a safe procedure with long-term anastomotic patency rates comparable with those of open-chest LIMA–left-anterior descending artery (LAD) bypass.
Key Words: Minimal invasive; Coronary surgery; Port access; Ischemic heart disease
Minimal invasive direct coronary artery bypass grafting (MIDCABG) has been introduced widely more than a decade ago [1]. This method of revascularization constitutes an attractive surgical option for patients with one-vessel coronary artery disease of the left anterior descending artery (LAD) or diagonal branches thereof, due to the easy accessibility via a sub-mammary incision. It is also recommended for patients destined for a ‘hybrid’ procedure, which involves revascularization of the LAD and stenting of additional coronary arteries in patients with more advanced disease. Other candidates may be patients with three-vessel disease and concomitant malignancies, severely reduced lung function and overall reduced life expectancy. Multiple registries are available, providing proof of patency through incomplete angiographic follow-up studies [2]. The majority of these studies does not constitute meta-analyses, and does not involve intra-operative, early and postoperative clinical evaluation, including angiographic follow-up, all together. Despite the plethora of published studies, the minimal surgical trauma and the avoidance of undesired CPB effects, controversy still exists, arising from the fact that MIDCABG procedures do not make up 2–5% of the coronary artery disease (CAD) surgical population in the submitting clinics, both sole LITA to LAD anastomoses and hybrid procedures. Regarding mortality, most of the clinical trials have demonstrated comparable mortality rates to conventional procedures but lower morbidity and clinical costs in favor of the minimal invasive approach [3]. However, a large cohort that provides postoperative incidence of complications and mortality, with angiographic controls, in relation to preoperative morbidity is not available at this point. The aim of this study was to provide a report over a large group of patients following MIDCABG procedure including intra-operative values, postoperative follow-up variables and angiographic patency rates, both in the early postoperative phase, and, so far obtainable, in the long-term follow-up.
The series included 390 patients, who had been operated from June 1996 onwards (male=69%; female=31%). Mean age was 61.6±10.4 years. Inclusion criteria were MIDCABG procedure to re-vascularize the LAD, or the first or second diagonal branch, or sequentially the LAD and one of the diagonals. Isolated LAD disease was present in 253 of 390 patients (64.9%). Two-vessel disease was present in 91 patients (23.3%), and three-vessel disease was found in 46 patients (11.8%). In 62 cases the LAD was totally occluded, in 76 patients the stenosis was severe (90–99%), in 157 cases the coronary stenosis was moderate (76–90%), and in 95 patients the stenosis was of lower degree (51–75%). The indication for MIDCABG in patients with two- and three-vessel disease was given if (a) the stenosis of the second and third vessels were not significant (clinically silent and <50%), (b) their localization was far too distal and thereof dependent myocardium was either scarred or aneurysmatic, (c) the second and third coronary targets were severely and globally calcified and of a <1-mm diameter, and (d) an operation using CPB appeared too risky, due to extensive co-morbidities. Exclusion criteria were (a) indication for off-pump coronary artery bypass grafting through a median sternotomy and (b) planned hybrid procedure. The description of the operative technique is well reported in multiple papers [3]. Demographics (Table 1), peri-operative events (Table 2) as well as early (<30 days) and late (>30 days) postoperative complications were evaluated. Additionally, early and late angiography were obtained. Postoperative angiographic morphology of the anastomosis was classified into four groups/degrees: A for ‘no stenosis’, B for ‘stenosis <50%’, C for ‘stenosis >50%, but patent graft’ and D for ‘total occlusion’.
2.1. Statistical analysis Descriptive statistics are presented as mean±standard deviation. All statistical evaluation was performed using the SPSS 11.0 Software. The follow-up time was expressed in patientsxyears (pt·yrs). The individual postoperative time spans for every single patient are summed, to calculate this number. For the present population it was 978.5 pt·yrs.
3.1. Early postoperative events (Tables 3 and 4) Early postoperative mortality (<30 days) was 0.8% (3 patients): two of them were of cardiac origin (0.5%) and suffered an extensive myocardial infarction and one patient died due to postoperative pneumonia (0.3%). Four patients had an early postoperative myocardial infarction (1.3%). Two of these patients experienced a re-infarction. Four patients (1.3%) had to be re-vascularized during the hospital stay following MIDCAB. In another three patients a postoperative angioplasty was performed, due to persisting angina in the context of patent anastomosis and additional symptomatic stenosis elsewhere (1%). In only 15 patients (5.1%) transfusion of blood products were necessary. The chest tube output was 400±353 ml. The mean postoperative ICU stay was 9.0±4.6 h, the overall hospital stay was 8.4±4.2 days. In summary, 376 of the 390 patients (96.4%) were alive, free of infarction, PTCA and additional CABG during the early postoperative period. 3.2. Early angiographic results (Table 4) In 238 of 390 patients (66.3%) the anastomotic evaluation was carried out within the first 30 days following MIDCABG. Coronary angiography was performed in 236 of these patients. Two patients were imaged by Doppler-sonography. Patency was found in 97.5% (232/238) of these patients, including 211 (88.6%) who had no stenosis (Grade A), 13 (5.5%) with a Grade B (<50%) stenosis and 8 (3.4%) with a Grade C (>50%) stenosis, but a patent graft. Only six patients (2.5%) had a total occlusion of the anastomosis (Grade D). Hence, a ‘patent’ anastomosis was present in (A+B+C) 232 of 238 patients (97.5%) who were also free of major adverse cardiac events (MACE).3.3. Late postoperative outcome [>postoperative day (POD) 30] and long-term follow-up (Table 4) Complete follow-up data were obtained from 291 of 390 patients (74.6%). Patients dropped out for various reasons, such as, inaccessibility (20%), non-compliance regarding the questionnaires (5%) and others. Long-term follow-up time was 30.0±11.2 months. Seventeen patients died in the long-term postoperative period (5.8%), whereas only five (1.7%) of these patients died due to a cardiac reason, such as acute myocardial infarction (n=2) and heart failure (n=1). Two patients were found dead, and an autopsy was not consented for. As the reason remained unclear, these two patients were counted to a cardiac reason. The other 12 patients (4.1%) died for non-cardiac reasons including stroke, COPD, renal failure and infection. Myocardial infarction occurred in nine patients (3.1%). In five of these patients (1.7%) this was a re-infarction. Half of these infarctions were located in the posterior wall of the heart (all these patients had two-vessel disease). Four patients required a CABG operation (1.4%). In three cases (1.0%) the LAD was once again a target vessel. Twenty-three patients received an angioplasty treatment in the long-term follow-up period (7.9%). In seven of these patients (2.4%) the target vessel was the MIDCABG target vessel (6xLAD, 1xfirst-diagonal), in the remaining 16 cases (5.5%) it was other coronaries as a result of the natural progression of the disease. Sixty-five patients (22.3%) reported postoperative angina. In 22 patients (7.6%) ischemic regions were identified by various types of imaging techniques (scintigraphy, FDG-PET). The anterior wall was affected in 12 patients (4.1%). A long-term postoperative stroke occurred in 10 patients (2.9%). The strokes occurred at 534±500 days postoperatively on average. In summary, 238 of the 291 patients (81.8%) were alive, free of infarction, PTCA and additional CABG during a follow-up period of 978.5 pt·yrs. 3.4. Late angiographic results (Table 4) The compliance for late postoperative angiography (>30 days) was 78 of 390 patients (20%) (response to follow-up call, and not due to their symptoms). Of these patients, patency was found in 93.6% (n=73) including 58 (74.4%) who had no stenosis (Grade A), 4 (5.1%) with a Grade B (<50%) stenosis and 11 (14.1%) with a Grade C (>50%) stenosis, but a patent graft. Only in five patients (6.4%), the anastomosis was occluded (Grade D). Hence, a ‘patent’ anastomosis was present in (A+B+C) 73 of 78 patients (93.6%).
Our study confirms (elsewhere reported) favorable outcomes following MIDCABG. The MIDCABG procedure is a safe, long-term efficient, and – with regards to its outcome–predictable surgical option for patients with one- or two- vessel coronary artery disease. The mortality and incidence of infarction are comparable or even better to those of conventional CABG [4] and angioplasty [5]. MIDCABG exhibits significantly lower re-intervention rates, as compared to PTCA [5]. However, it appears that angina is a common event following MIDCABG in the long term, most probably due to progress of the disease of the native coronaries. A series of short-term results following MIDCABG has been already published [6]. In these studies, postoperative infarction rates range between 1% and 5%. Of note, many of these studies were carried out without the use of mechanical stabilization. The frequency of conversion reported elsewhere varies between 0 and 6% [7, 8]. It is generally reported, and confirmed by the present study, that a conversion – regardless of cause – can be performed rapidly and safely for the patient. We could also confirm the low rate of peri-operative re-interventions after MIDCABG operation, in compliance with most of the studies involving MIDCABG patients, with the exception of that of Calafiore et al. who reported 6%, and attributed this to surgical learning curves. In total, rhythm disturbances were low during the procedure, mainly at the point of LAD-occlusion for the accomplishment of the anastomosis. Our tactic involves a 2-min preliminary occlusion and release of the target artery for the purpose of ischemic preconditioning. Of course, these intra-operative rhythm disturbances might have been further minimized, had we systematically applied an intra-coronary shunt and not only in two patients of the series (0.5%). Numerous reports are available suggesting a standardized use of shunts to prevent ischemia [9]. Blood transfusion requirements were comparable with those reported in preceding studies and postoperative atrial fibrillation was the lowest reported so far [7, 10], even though Hravnak et al. could show that the occurrence of atrial fibrillation following MIDCABG is rather related to preoperative concomitant conditions than intra-operative factors [11]. Our early mortality of 0.8% was better than that reported by Stanbridge and Hadjinikolaou, who published one of the most voluminous meta-analysis involving 3000 patients [4]. Patency rates for LIMA–LAD anastomoses of 97.4% (early angiographic results/n=232/238) and 93.6% (late angiographic results/n=73/78) are equivalent to those of conventional CABG patients. Similarly, our rate of re-interventions was low compared to related reports for MIDCAB or CABG (Mariani et al. [12] re-CABG: 3.1%; re-PTCA: 3.0%, Calafiore et al. [7] re-CABG: 7.8% and following introduction of mechanical stabilizers: 2.1%; re-PTCA: 0.7%). Interestingly, the re-intervention rate in our patient population (follow-up 30±11 months) does not seem to further deteriorate compared to the ones reported, usually at ca. 15 months postoperatively on average. Of note, only 7 of the 23 patients who required postoperative PTCA received this in the anastomosed target vessel. The rest of the patients with postoperative PTCA (16/23) obviously had natural progression of the coronary artery disease. Our results are in compliance with Diegeler et al. who found that stenting yields excellent short-term results with fewer peri-procedural adverse events, but surgery is superior with regard to the need for repeated intervention in the target vessel and freedom from angina at six months of follow-up [13]. In contrast, longer follow-up times seem to correlate with a higher incidence of stroke, even though it is not generally believed that the latter are related to the MIDCABG procedure itself. In conclusion, this 1000 pt·yrs follow-up indicates the efficacy and safety of MIDCABG. Low rates of re-interventions and high patency rates constitute the merit of this operative approach. 4.1. Comparison of MIDCABG with CABG outcome Our long-term results with regard to mortality, postoperative infarction and re-interventions are similar to those reported for conventional CABG patients [14]. Bleeding and blood requirements were even lower than those reported by others, such as by Arom et al. for CABG patients [15]. Various other complications, such as pulmonary edema or neurological complications, were all less frequent in our series. A fairly large number of patients were not accessible in the long-term, or failed to answer the questionnaire. Hence, the number of dropouts is sizeable. They may indeed affect the result to some extent. Similarly, only a portion of the patients volunteered an additional angiography in the long-term, to have their anastomosis evaluated as they may have moved or had concerns about the postoperative angiography.
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Abstract
1. Introduction