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Eur J Cardiothorac Surg 2002;22:124-128
© 2002 Elsevier Science NL
a Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, Bristol, England BS2 8HW, UK
b Department of Social Medicine, University of Bristol, Bristol, UK
Received 13 September 2001; received in revised form 17 January 2002; accepted 26 March 2002.
* Corresponding author. Tel.: +44-117-928-3145; fax: +44-117-929-9737
e-mail: g.d.angelini{at}bristol.ac.uk
| Abstract |
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70 years) underwent coronary revascularisation, 219 (22.1%) with off-pump surgery. Elderly patients were more likely to have higher CCS, NYHA and EuroScores, history of previous MI, unstable angina, renal dysfunction, left main stem disease
50%, and to be urgent. However, they were less likely to be overweight. In-hospital mortality, occurrence of re-intubation, renal dysfunction, and hospital stay were significantly higher in this elderly group. Overall, the distribution of mortality was doubled in the female gender although this was not statistically significant. Patients undergoing on-pump surgery had lower EuroScore, were less likely to be >75 years of age, likely to have obesity or hypercholesterolaemia, or to have suffered a previous cerebro-vascular accident. However, they had more extensive coronary disease, were more likely to have unstable angina, and received more grafts than those undergoing off-pump surgery. After adjustment for prognostic variables, off-pump surgery was found to be associated with reduced inotropic use, intra-operative arrhythmias, blood loss and transfusion requirement when compared to on-pump coronary surgery (point estimates of odd ratios, 0.260.87) (all P<0.05). Mid-term mortality or cardiac-related events were similar in the two groups. Conclusions: Early but not mid-term mortality is higher in patients aged 75 or more years when compared with those aged 7074 years. Off-pump coronary artery bypass surgery is safe and effective in the elderly population.
Key Words: Clinical outcome Coronary artery bypass grafting Elderly
| 1. Introduction |
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In a recent randomised controlled trial, we demonstrated that performing coronary surgery on the beating heart without the extra-corporeal circulation reduces morbidity in elective patients when compared with conventional technique [3]. However, little is known about the efficacy of off-pump coronary artery bypass surgery in elderly patients.
The use of a high quality prospective database in our institution created the opportunity to evaluate the influence that age and modern techniques of coronary surgery have on early- and mid-term clinical outcome in patients over 70 years old.
| 2. Patients and methods |
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70 years old) who had undergone coronary revascularisation during the study period. Allocation to on- and off-pump surgery was on the basis of the preference and expertise of the surgeons carrying out the operations and, also, during the early part of data collection when experience was still being gained with off-pump techniques, the allocation was based on coronary anatomy and number of grafts required. The decision about which surgical method to use was taken after opening the chest, when the anatomy of the coronary vessels could be explored.
2.2. Anaesthetic and operative technique
Anaesthetic technique and heparin management were standardised and have previously been reported [4]. In the on-pump group, cardiopulmonary bypass was instituted using ascending aortic cannulation and two-stage venous cannulation of the right atrium. A standard circuit was used a Bard tubing set, which included a 40-µm filter and a hollow fibre membrane oxygenator (Sorin Biomedica, Midhurst, UK). The extracorporeal circuit was primed with 1000 mL of Hartmann's solution, 500 mL of Gelofusine, 0.5 g/kg mannitol, 7 mL of 10% calcium gluconate, and 6000 IU of heparin. Non-pulsatile flow was used and flow rates throughout bypass were 2.4 L/m2/min. Systemic temperature was kept between 34 and 36°C. Myocardial protection was achieved with intermittent anterograde hyperkalaemic warm blood cardioplegia [4].
In the off-pump group, we used two methods of exposure and stabilisation of the heart previously described [5,6]. Briefly, the target vessel was exposed and snared above the anastomotic site using a 4-0 prolene suture with a soft plastic snugger to prevent coronary injury. The coronary target area was stabilised with a reusable stabiliser (Abbey Surgical Limited, Mitcham, Surrey, UK). An intra-coronary shunt (Anastoflo Intravascular Shunt; Research Medical Inc., Midvale, Utah, USA) was used only in case of relative electrocardiographic or haemodynamic instability or excessive bleeding during the anastomosis.
2.3. Postoperative management
At the end of surgery, patients were transferred to the intensive care unit (ICU) and managed according to a standard unit protocol as previously reported [4]. Forced air warming was used, until a stable nasopharyngeal temperature of 37°C had been reached. Patients were extubated as soon as they met the following criteria: haemodynamic stability, no excessive bleeding (<80 mL/h), normothermia, and consciousness with pain control. Fluid management postoperatively consisted of 5% dextrose infused at 1 mL/kg/h, with additional Gelofusine or blood to maintain normovolemia and hematocrit greater than 24%. Potassium and magnesium deficiencies was promptly treated as necessary to mantain electrolyte balance within the normal range.
2.4. Clinical data collection, monitoring and definitions
Data characterising peri-operative clinical outcome were entered prospectively into the Patient Analysis and Tracking System. In-hospital mortality was defined as any death that occurred within 30 days of operation. Peri-operative myocardial infarction, ST segment changes, pacing, arrhythmias and inotropic requirement were recorded and defined as previously reported [4]. Pulmonary complication included chest infection, ventilation failure, re-intubation and tracheostomy [4]. Postoperative blood loss was defined as total chest tube drainage [7]. Neurological complication included permanent and transient stroke [8]. Renal complication included acute renal failure as defined by the requirement of haemodialysis. Finally, infective complication included septicaemia, sternal and leg wound infection as defined by positive culture and requiring antibiotic therapy [4].
2.5. Statistical analysis
First, patients were divided into two groups according to the following age: group A: 7074 years old; group B: 75 or more years old. Patients were also divided according to the surgical technique used. These groups were compared using a Chi square test for categorical variables and a MannWhitney test for continuous variables. Conversions from off- to on-pump surgery were analysed in the off-pump group, i.e. by intention-to-treat. Outcomes for the respective on- and off-pump sub-groups were compared both with and without adjusting for possible confounding, using multiple linear or logistic regression depending on whether the outcome was a dichotomous or continuous variable. Our interpretation of the findings takes into account the consistency of the findings and their magnitude, as well as their statistical significance.
| 3. Results |
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70 years underwent coronary artery bypass surgery. Of these, 659 (66.5%) were allocated to group A (age 7074 years), and 331 (33.5%) to group B (age 75 or more years). The majority of patients (771, 79.9%) had on-pump surgery. The proportion of off-pump operations carried out increased steadily during the study period (see Fig. 1
). There were two conversions to on-pump surgery amongst patients in whom a decision to carry out off-pump surgery had been made.
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50%, and to be urgent. However, they were less likely to be overweight. In-hospital mortality, occurrence of re-intubation, renal dysfunction, and hospital stay were significantly higher in this elderly group (all P<0.05) (Table 2). Female gender was associated with a doubled mortality when compared with male (3.4% vs. 1.6%), but this did not reach statistical significance.
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The mid-term follow-up analysis showed no difference between the two age groups on late mortality or cardiac-related events (Table 5). Similar results were found with respect to the surgical technique used (data not shown).
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| 4. Discussion |
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The analysis carried out in the present study focused first on the influence of increasing age and subsequently of the effectiveness of the modern surgical techniques on early and late clinical outcome. The group of patients aged 75 or more years had a significantly higher in-hospital mortality, occurrence of re-intubation, renal dysfunction, and hospital stay. However, this group presented to surgery with the worse clinical conditions as showed by the analysis of baseline characteristics.
Although the number of females is relatively small in our series, it is striking to observe that this was associated with a trend of higher mortality when compared with male gender as reported by others [11].
Although the adverse effects of cardiopulmonary bypass (CPB) are minor and reversible in most patients, these may be of major importance, irreversible, and even fatal in elderly patients [12]. The incidence of non-fatal complications reported for elderly patients after CABG ranges from 30 to 73% [13], with an in-hospital mortality rates of 524% [13]. Recent long-term data from the Coronary Artery Surgery Study (CASS) showed that 59% of patients aged 75 years at the time of surgery are alive 10 years after surgery, while 33% are alive for 15 years [14]. These data appear to support an aggressive approach to the treatment of coronary artery disease in the elderly, also in view of the fact that elderly patients have a higher rate of percutaneous transluminal coronary angioplasty (PTCA)-related complications, with a reported mortality rates of 27% [15,16].
Recently, off-pump surgery has gained popularity worldwide, with the potentiality of reducing surgical morbidity by avoiding the use of CPB [1721]. While the majority of the studies on off-pump surgery have focused on younger patients, elderly patients might in fact benefit the most from the use of this technique.
The investigation on the influence of off-pump surgery on early clinical outcome in this elderly population was therefore another primary end-point of the present study. In our series, off-pump surgery when compared with conventional CABG was associated with reduced inotropic requirements, blood loss and transfusion requirement. These findings are in accordance with other recent reports suggesting that off-pump surgery may reduce in-hospital morbidity in elderly surgical patients [1,2,9].
At mid-term follow-up, neither the different degree of elderly nor the surgical technique employed had an influence on mortality and cardiac-related events. The overall incidence of late mortality, however, was low in both groups supporting a more aggressive policy of coronary revascularisation in these patients.
In conclusion, this study suggests that patients aged 75 or more years and undergoing coronary revascularisation present with worse clinical status and have higher in-hospital mortality and morbidity when compared with patients 7074 years old. Off-pump coronary surgery is safe and effective in elderly patients. The overall low incidence of late mortality supports a more aggressive policy of coronary revascularisation in these patients.
| Footnotes |
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| References |
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