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J Thorac Cardiovasc Surg 1998;116:578-583
© 1998 Mosby, Inc.
SURGERY FOR ADULT CARDIOVASCULAR DISEASE |
Montpellier, France
From the Departments of Cardiovascular Surgerya and Cardiology,b Arnaud de Villeneuve Hospital, Montpellier, France.
Received for publication Nov 14, 1997. Revisions requested Feb 6, 1998; revisions received March 26, 1998. Accepted for publication June 16, 1998. Address for reprints: Jean-Marc Frapier, MD, Chirurgie Cardiovasculaire Service du Pr Chaptal, Hopital Arnaud de Villeneuve, 34059 Montpellier Cedex, France.
| Abstract |
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| Introduction |
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| Patients and methods |
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Methods.
Indications.
All patients had an anterior MI. They were referred for surgical treatment (1) if their VT was unresponsive to medical treatment or the antiarrhythmic medications had to be stopped because of major side effects or (2) if there was an indication of associated disease, such as congestive heart failure over an anteroapical aneurysm or angina with graftable coronary arteries.
Low ejection fraction was not considered a contraindication, especially in the presence of a large anteroapical aneurysm. However, patients with poor contraction of the other segments on the right or left anterior oblique projection of the ventriculogram, or on the echocardiogram, and/or diffuse coronary disease with target vessels less than 1.5 mm, were not selected for this type of operation and were referred for AICD implantation.
Preoperative study protocol.
The preoperative study protocol included a Holter electrocardiogram (ECG), echocardiogram, cardiac catheterization, coronary arteriogram, and electrophysiologic studies (EPS). EPS were performed 24 to 48 hours after antiarrhythmic drug cessation in 28 (73.6%) patients who were in stable condition. The stimulation protocol consisted in apical ventricular premature beats (1, 2, and up to 3 extrastimuli) with increasing prematurity on a 500-ms basic cycle length. A sustained VT was the end point of the EPS protocol. Ten (26.3%) patients who were in unstable condition were deemed unsuitable for preoperative EPS.
Operative technique.
During cardiopulmonary bypass, when cooling to moderate hypothermia (28°C) when necessary, the proximal saphenous vein graft anastomosis was performed first. With the aid of cardioplegic arrest, the ablative procedure was carried out by way of a left ventriculotomy through the scar, as first described by Guiraudon and associates,
13 without mapping. Points of cryolesion were either edge to edge or overlapping and applied 1.5 cm outside the area of the visible scar in all patients. In the septum, where the exact delimitation of the scar is less easy, this distance of 1.5 cm was increased so that a second row could be applied. Care was taken to avoid ablation in the upper part of the septum near its membranous portion, which can cause a His bundle block (which happened twice at the beginning of our experience). Cryoablation was performed with a Frigitronics cryosurgical system CCS 100 with a 15-mm diameter flat face curved probe (CooperSurgical Inc, Shelton, Conn). A mean of 11.4 ± 2.2 cryolesions (range 8-15) was realized at a mean temperature of 61°C (range 50°C to 74°C) for 2 minutes per point. The principal associated procedures were aneurysmectomy and coronary artery bypass surgery. Thirty-eight (100%) patients underwent aneurysmectomy, with a Jatene procedure in 12 (31.5%). The 12 (31.5%) patients who required coronary artery bypass received a total of 18 grafts (mean 1.5 grafts per patient). The mean cardiopulmonary bypass time was 109 ± 45 minutes (range 48-251 minutes), and the average crossclamp time was 37 ± 24 minutes (range 25-94 minutes).
Postoperative protocol.
At postoperative day 14, the patients were subjected to EPS with the same protocol as used before the operation, by way of the temporary right ventricular epicardial leads, as well as a Holter ECG, and echocardiogram. After EPS, patients were maintained on a program of amiodarone (200 mg daily) for 6 months, which was subsequently discontinued except in the presence of abnormal EPS or Holter ECG findings during the postoperative period or in the presence of atrial fibrillation.
Evaluation and definitions.
Results of EPS were considered abnormal only if a sustained VT (>30 seconds) was inducible, irrespective of its morphology. Electrical success was defined by abnormal EPS and Holter ECG results during the postoperative period. Clinical success was defined by the absence of spontaneous VT with or without antiarrhythmic medication after surgery (corresponding to freedom from VT). Sudden cardiac death, defined as death occurring within 1 hour of onset of symptoms in an otherwise clinically stable patient, was considered as recurrent VT. Heart transplantation during the follow-up was counted as death from congestive heart failure.
Follow-up.
Patients were traced for a mean follow-up of 61.9 ± 38.5 months (range 3-124 months). One Portugese patient was lost to follow-up at 3 months. He was included in the in-hospital results but was eliminated from rough long-term results. He was included in the actuarial results as censored data. Data were obtained via questionnaires to the patient's referring physician and cardiologist or by consultation in the outpatient clinic of the Cardiology Unit of Arnaud de Villeneuve Hospital.
Statistical analysis.
Preoperative and perioperative data were obtained by reviewing the patients' hospital records. All data were entered into a computer for statistical analysis with SAS statistical software (SAS Institute, Inc, Cary, NC) at the medical statistics department of the hospital. Data are expressed as a mean ± standard deviation. Statistical analysis was performed by Wilcoxon paired t test for comparison between 2 periods. Actuarial survival and freedom-from-events curves were prepared according to the Kaplan-Meier method.
| Results |
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Late mortality after surgery was 44.4% (16/36 patients): 38.8% (14 patients) died, and 5.5% (2 patients) underwent heart transplantation. The main cause of death was congestive heart failure (62.6% of late mortality), but sudden cardiac death occurred in 5.5% (2 patients). At 5 and 7 years, the overall actuarial survivals (Fig 1) were 63% (95% CI 47%-80%) and 42% (95% CI 22%-63%), respectively. Freedom from sudden cardiac death was 91% (95% CI 80%-100%) at both 5 and 7 years.
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Rhythm.
The electrical success rate based on postoperative EPS was 94.5% (35/37 survivors). One patient had polymorphic sustained VT, but VT did not develop during follow-up. Another patient had monomorphic sustained VT comparable with the preoperative VT; this patient had a nonfatal recurrent VT during follow-up. In a third patient with polymorphic nonsustained VT, the procedure was not considered to have been a failure according to the aforementioned definition. Two patients had a VT recorded on Holter ECG or on intensive care unit monitoring. They had nonfatal recurrent VT during follow-up. The overall electrical success rate was 89.1% (33/37 survivors).
The clinical success rate was 83.3% (30/36 survivors). Six patients (16.7%) had arrhythmias that could not be controlled. Two of these 6 patients died of sudden cardiac death at 21 and 48 months, and 4 patients had nonfatal recurrent VT. Freedom from VT was 77% (95% CI 61%-94%) at both 5 and 7 years (Fig 2).
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| Discussion |
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After initial experiences with map-guided subendocardial resection and localized cryolesions, we turned to large encircling cryoablation without mapping. This decision was influenced by our observations that, especially with quadripolar hand-held electrodes, mapping was not successful in all patients after ventriculotomy (mapping success rate of 63%, unpublished data). Moreover, in the majority of patients with anterior MI, the earliest activation or cryotermination site was located within the area of the visible scar tissue. Although large blind endocardiectomy has produced consistently high success rates,
4,11 the arduous nature of this procedure—particularly when performed on mitral papillary muscle or interventricular septum—compelled us to perform large encircling cryoablation.
Although unsuccessful mapping or "no mapping" has been documented as a prominent risk factor for failure by several authors,
9.10,23 it was not a significant factor of failure in some series.
19-22 Even with computerized mapping, with which one can achieve a 100% rate of successful mapping, the highest electrical success rates ranged from 72% to 87%.
23,24 Results from our large encircling cryoablations were similar to those obtained by Guiraudon and associates,
13 with an electrical success rate of 94.5%. Furthermore, although mapping was used in their series, they saw no difference in electrical success rates between patients with successful or unsuccessful intraoperative mapping.
20 In addition, as argued by Guiraudon and colleagues,
13 map-guided surgical procedures were often regional or large procedures rather than truly localized, as assessed by the surgical protocols described in various reports.
4,9,17,18 Finally, Cox,
8 in his collaborative report, revealed no significant difference in the postoperative rate of VT inducibility between 179 patients treated by localized procedures versus 342 patients treated by generalized techniques.
We report a post-cryoablation freedom from sudden cardiac death of 91% (95% CI 80%-100%) at both 5 and 7 years. However, our results concerning overall survival were far from ideal, with overall actuarial survivals of 63% (95% CI 47%-80%) and 42% (95% CI 22%-63%) at 5 and 7 years, respectively. This lower survivorship could be explained, in part, by the mean length of our postoperative follow-up (61.9 ± 38.5 months), which is significantly longer than is reported in other studies. Furthermore, unlike other series,
23 patients over 65 years old were not rejected from our series. Moreover, despite an improvement in the postoperative LVEF, the preoperative LVEF of our series was 29%. It has been demonstrated that an LVEF of less than 31% is a strong predictor of late postoperative mortality.
25 Undoubtedly, our revascularization rate of 31% had been too weak. Mickleborough and associates,
23 in their series, had an 85% rate of coronary artery bypass, and in many other reports this rate was about 70%.
24,25
Death after operation for ischemic VT is rarely due to recurrent VT.
23 The main cause of late postoperative death remains congestive heart failure. We believe that sustained improvements in left ventricular function, by ventricular remodeling and extensive revascularization,
23 should improve overall long-term survivals. Adding a more drastic selection of patients, by using the quality of the residual left ventricular function as a criterion for operability,
26 in the era of other alternatives
1,2 should lead to excellent outcome.
Study limitations.
In this series, only 65.7% (25/38) of patients who underwent large encircling cryoablation had intractable VT (eg, uncured by preoperative antiarrhythmic drug treatment). Indications for surgery in the other 34.3% (13/38) were primarily congestive heart failure, myocardial ischemia, or both. Amiodarone was used before the operation and was stopped the day of the operation in all responsive patients. Because of the long-lasting half-life of amiodarone, it is likely that the electrical success rate based on postoperative EPS would have been lower if all patients had been nonresponsive. Moreover, amiodarone treatment was continued for 6 months after cryoablation, irrespective of postoperative EPS results. It is possible that our clinical success rate would have been lower if all 38 patients had been nonresponsive to medical therapy.
| Conclusion |
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| Acknowledgments |
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| References |
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