Eur J Cardiothorac Surg 1998;13:555-558
© 1998 Elsevier Science NL
CABG shortly after AMI treated with thrombolysis: an analysis of the surgical group and a comparison with PTCA in the DANAMI study1
Erik Hjelmsa,
Poul Alstrupa,
Peter K. Paulsenb,
Uffe Niebuhr-Jørgensenc,
Lars Ib Andersend,
Henrik Arendrupe
a Department of Cardiothoracic Surgery, Aalborg, Denmark
b Department of Cardiothoracic Surgery, Aarhus, Denmark
c Department of Cardiothoracic Surgery, Gentofte, Denmark
d Department of Cardiothoracic Surgery, Odense, Denmark
e Department of Cardiothoracic Surgery, Rigshospitalet Copenhagen, Copenhagen, Denmark
Received 1 October 1997;
received in revised form 11 February 1998;
accepted 16 February 1998.
Corresponding author. Department of Cardiothoracic Surgery, University Hospital 901 85, Umeå, Sweden. Tel.: +46 907 853676; fax: +46 907 853601.
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Abstract
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Objective: To present surgical results of the DANAMI study comparing conservative and invasive treatment of postinfarction myocardial ischaemia and to compare these with percutaneous transluminal angioplasty (PTCA) which was the alternative invasive treatment in that study. Methods: A group of 413 patients with verified acute myocardial infarction treated with thrombolysis within 12 h of the onset of symptoms, who demonstrated postinfarction myocardial ischaemia were treated with coronary bypass grafting (CABG) or PTCA. Patients with left main lesions, three-vessel disease, two-vessel disease with more than three stenoses and patients with occlusions of a non-infarct related vessel had primary CABG. Patients with 1- and 2-vessel disease with not more than a total of three stenoses had PTCA. In case of failed PTCA patients had secondary CABG. The median distance from AMI to CABG was 45 days. PTCA was performed at a mean of 39 days after the infarction. Results: A total of 147 patients had CABG and 266 had PTCA. The operative mortality for CABG was 1.4%. No PTCA patients died in relation to the procedure, 0.8% developed acute myocardial infarction as a consequence of the procedure, 1.5% had acute CABG and 3.5% elective CABG due to failed PTCA. In spite of more severe coronary artery disease among the CABG patients there was no difference in survival at 2.4 years. The CABG group had significantly fewer episodes of unstable angina, 10.2% versus 25.6% (P=0.0002). No CABG patients had re-do revascularisation at 2.4 years follow-up versus15.4% of the PTCA patients. At 3 years 80% of the CABG patients were free of angina compared to the 61% of the PTCA group (P<0.0001). Conclusion: Low morbidity and mortality justifies the deferred elective revascularisation in patients with postinfarction myocardial ischaemia even in patients with silent ischaemia. There is no difference in survival at 2.4 years between CABG and PTCA but CABG offers more lasting results concerning incidence of stable and unstable angina than PTCA, which, however, is a valuable alternative in patients with less severe coronary artery disease.
Key Words: Coronary artery bypass grafting • Postinfarction ischaemia • Percutaneous transluminal angioplasty
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Introduction
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The treatment of postinfarction myocardial ischaemia has until recently been medical; mainly because it was generally accepted that cardiac surgery within months after acute myocardial infarction was contraindicated due to significantly higher mortality and morbidity. However, several retrospective studies have now indicated that early coronary artery bypass grafting (CABG) after acute myocardial infarction in stable symptomatic patients carries no increased operative mortality compared to operations more remote, i.e. more than 3 or 4 months after infarction
[1]
[2]
[3]
[4]
[5]. The predictors of increased perioperative mortality and morbidity were found to be age, unstable angina and impaired left ventricular function rather than the interval from acute myocardial infarction to CABG
[6].
The main purpose of the DANAMI study
[7] was to evaluate any benefit of invasive treatment compared with conservative treatment of postinfarction ischaemia. A significant difference in survival at 2.4 years was not found, but in terms of new myocardial infarctions, episodes of unstable angina and of combined end-points the invasive group fared significantly better. The purpose of the present study is to report the results of the surgical group of the DANAMI study and to compare them with those of the PTCA group in the same study.
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Materials and methods
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The study included 147 patients who had CABG and 266 patients who had PTCA for postinfarction myocardial ischaemia. Together they formed the invasive group of the DANAMI study. Selection and allocation of PTCA or CABG in the invasive group has been given previously
[7]. In brief, patients in the DANAMI study were collected from 43 different Danish hospitals after admission for a first acute myocardial infarction (AMI) treated with thrombolysis. Patients with left bundle branch block, previous PTCA or CABG were excluded. Included were patients 69 years old or younger who demonstrated postinfarction myocardial ischaemia at a bicycle stress test before discharge. Patients had either angina plus ECG changes, angina with no ECG changes or diagnostic ECG changes at stress test with no angina – silent myocardial ischaemia. After randomisation the invasive group had coronary arteriography performed and patients were allocated to either PTCA or CABG according to coronary pathoanatomy. Patients with three-vessel disease, with two-vessel disease with a total of more than three stenoses, with left main stenosis and patients with occlusion of a non-infarct related vessel had CABG. Also patients in whom a PTCA was unsuccessful were treated with CABG. PTCA was performed in patients with one- and two-vessel disease with no more than three stenoses. They were scheduled to treatment within 2 and 5 weeks, respectively. Details of the surgical group and the operations are shown in Table 1 and Table 2. There was no significant difference between the CABG and PTCA groups in terms of gender, age, ejection fraction (EF) or percent with silent ischaemia.
All patients were seen at the outpatient clinics at 1 year and a follow-up check was performed at a median of 2.4 years. A questionnaire investigation regarding recurrent angina (unstable as well as stable) was carried out at 22 months after inclusion was stopped.
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Statistics
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The results of the questionnaire investigation were evaluated with the 
2-test. Other comparisons between the CABG and PTCA patients were done using the log rank test.
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Results
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The operative mortality in the CABG group, 30 days or hospital, was 1.4% or two patients. One of these patients suffered irreversible brain damage and the other developed renal failure requiring dialysis. Four percent suffered perioperative myocardial infarction, judged on ECG criteria. A total of 6% needed postoperative mechanical circulatory support, 4.8% intraaortic balloon pumping, 1.4% left ventricular assist device, respectively. In the CABG group 85% and in the PTCA group 95% of the patients were considered to have complete revascularisation.
In the PTCA group there was no procedure-related mortality, 0.8% suffered infarction and 1.5% had acute CABG. Elective CABG was done in 3.5% due to failed PTCA.
Follow-up results and comparison between PTCA and CABG are shown in
Fig. 1
. There was a significant difference in episodes of unstable angina favouring CABG, 10.2% versus 25.6% (P=0.0002). Patients with silent ischaemia had significantly fewer episodes of unstable angina in both treatment groups.
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Fig. 1. Follow-up at 2.4 years in the DANAMI trial. Comparison between results of CABG and PTCA and between symptomatic and silent ischaemia within each treatment group. There are significantly more episodes of UAP among symptomatic patients in both treatment groups and in the PTCA group compared to CABG; but no difference in mortality or new infarctions. AB, symptomatic ischaemia; C, silent ischaemia; UAP, unstable angina; AMI, acute myocardial infarction.
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The questionnaire investigation of total incidence of angina, stable as well as unstable, showed a significant difference, 80% versus 61% in freedom from angina at 3 years for CABG and PTCA, respectively (P<0.0001).
During the follow-up up to 2.4 years the incidence of re-do procedures was 15.4% in the PTCA patient group with 8.6% having re-PTCA and 6.7% CABG. No patients in the CABG group had repeat revascularisation procedures performed.
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Discussion
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The overall result of the DANAMI study demonstrated the superiority of deferred invasive treatment to the conservative treatment
[7]. Fifty percent of the patients in the CABG group had silent ischaemia, a condition which would not have prompted surgery had they not participated in the study. To justify CABG soon after myocardial infarction it is therefore of importance to clarify whether CABG contributed equally with PTCA to the positive result in the invasive group of the DANAMI study. It is also important to demonstrate that CABG at this stage in these patients carries no higher morbidity and mortality than elective surgery, remote from acute myocardial infarction, in symptomatic patients. The operative mortality in this study was 1.4% and is comparable with other studies from the same period of time. Curtis et al.
[2] reported an operative mortality of 0.83% in patients with stable angina and no previous infarction. The SWIFT trial
[8], which investigated invasive treatment after thrombolysis of acute myocardial infarction irrespective of the presence of postinfarction myocardial ischaemia, had a CABG operative mortality of 1.7%. In the recent randomised studies comparing CABG with PTCA CABG operative mortality varied from 4.7% in the ERACI trial
[9] to 1.3% in the BARI
[10], 1.2% in the RITA
[11] and 1.0% in the EAST study
[12].
With our results in terms of low operative mortality and morbidity, the intermediate term good relief of angina and significant reduction in new myocardial infarctions, it seems justified to advocate CABG to patients with postinfarction myocardial ischaemia, even in silent ischaemia. The alternative invasive treatment, PTCA, has in this study demonstrated equal potential to prevent new myocardial infarctions. However, it does not have the same lasting effect on neither stable nor unstable episodes of angina and leads subsequently to significantly more re-do procedures compared with CABG in spite of less severe coronary artery disease in the PTCA patients of this study. This is in accordance with the randomised studies of CABG versus PTCA
[9]
[10]
[11]
[12] and with the ACIP study
[13].
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Conclusion
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Low morbidity and mortality justifies deferred elective revascularisation in patients with postinfarction myocardial ischaemia, even in patients with silent ischaemia. There is no difference in survival at 2.4 years between CABG and PTCA but CABG offers more lasting results concerning incidence of stable and unstable angina than PTCA, which, however, is a valuable alternative in patients with less severe coronary artery disease.
For the full list of participating investigators please see Ref.
[7].
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Footnotes
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Presented at the 11th Annual Meeting of the European Association for Cardio-thoracic Surgery, Copenhagen, Denmark, September 28 – October 1, 1997. 
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Appendix A. Conference discussion
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Dr T. Kaul (Birmingham, AL, USA): In a similar multi-institutional study (Every et al., Circulation 1996;94 Suppl. II-85), management strategies used in 11 176 patients who presented with acute myocardial infarction were evaluated and compared with other recent reports including mine (Ann Thorac Surg, 1995;59:1169–1176). In our study, which was from a single institution, the entire infarct population was 2922 patients in a 5-year study period. Of these, 46% underwent thrombolysis only. With 10% hospital mortality, 20% underwent PTCA, the mortality was 2.5% and 642 (22%) patients underwent CABG. The mortality in our surgical patients was 5.9%, which included 100 reoperative patients, 42 patients in cardiogenic shock, 171 (26.6%) patients aged 70 years or older and many other high-risk patients. The purpose of highlighting this is that one should use different strategies in acute myocardial infarction as appropriate. In our series, surgical intervention, or CABG was performed within the first 24 h in 26% of patients, 68% of our patients were operated within the first week after an acute myocardial infarction, and 95% of our patients were operated within 2 weeks of acute myocardial infarction. If you use surgical intervention early in acute myocardial infarction, you actually reduce the mortality of the entire population of patients presenting to you with acute myocardial infarction. The overall mortality in our series has been much lower than what has been described in other multi-institutional studies and also in the National Registry for Myocardial Infarction in the United States. This is the advantage of performing a surgical intervention in acute myocardial infarction at an early stage. The 10-year survival of these patients was 75%, which is slightly lower than the patients undergoing CABG procedure without infarction, nonetheless it is quite satisfactory.
Dr Hjelms: As I understood, it is really in line with what we have shown here. Of course, there was no emergency operations in our series. And of course, that makes a difference. However, it has been shown, although only in retrospective studies, that the main risk of doing CABG early after myocardial infarction is really not the time as long as you are a couple of days away from the infarction. It is more the left ventricular function and perhaps the age of the patient.
Dr Kaul: Quite often the condition of these patients deteriorates and you may not get a chance to operate. So that is why we recommend early surgery. And if you do that, you can get a good recovery with fewer complications, low mortality and low morbidity. That is the advantage of an earlier intervention. Early surgical intervention was performed in our high-risk patients. Post infarct LVEF <30% emerged as an independent predictor in both early and late phases. In patients 70 years or older (n=171), an early CABG was advantageous, because hospital mortality was higher when intervention was delayed for 1 week or more.
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References
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Abstract
Introduction
