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Ann Thorac Surg 2008;85:1278-1281. doi:10.1016/j.athoracsur.2007.12.035
© 2008 The Society of Thoracic Surgeons
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Original Articles: Adult Cardiac

Early and Late Survival After Surgical Revascularization for Ischemic Ventricular Fibrillation/Tachycardia

Dumbor L. Ngaage, MD, FRCS (C-Th)*, Alexander R.J. Cale, MD, FRCS (CTh), Michael E. Cowen, FRCS, Steven Griffin, FRCS (C-Th), Levant Guvendik, FRCS

Castle Hill Hospital, Kingston-Upon-Hull, East Yorkshire, United Kingdom

Accepted for publication December 11, 2007.

* Address correspondence to Dr Ngaage, Department of Cardiothoracic Surgery, Castle Hill Hospital, Kingston-Upon-Hull, East Yorkshire, HU16 5JQ, United Kingdom (Email: dngaage{at}yahoo.com).


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 References
 
Background: Ischemic ventricular fibrillation/tachycardia (VF/VT) treated by myocardial revascularization, often with an implanted cardioverter defibrillator, prevents sudden cardiac death. Early series have suggested that recurrent VF/VT threatens survival even after treatment. As late outcome is unknown, we sought to determine if the early survival benefit is sustained.

Methods: From January1999 through January 2007, 93 consecutive patients (75 male, 81%) presented with ischemic VF/VT; 21% survived cardiac arrest and underwent coronary artery bypass graft surgery at our institution. We analyzed their early and late survival.

Results: Median age was 66 years (range, 44 to 88). Clinical presentation included class III/IV angina (46%), controlled heart failure (43%), prior myocardial infarction (68%), left ventricular ejection fraction less than 0.30 (23%) and 0.30 to 0.50 (35%), left main stem disease (24%), and triple-vessel disease (67%). Surgical revascularization, mostly nonelective (urgent 73%, emergency 7%), was combined with aortic valve replacement in 5 patients and left ventricular pseudoaneurysm repair in 3. Ischemic territories and mean number of diseased coronaries (2.6) corresponded to the grafted territories and average number of grafts (2.5). Operative mortality was 6.5% (n = 6, median EuroSCORE [European System for Cardiac Operative Risk Evaluation] predicted mortality 9). Recurrent VF/VT occurred early postoperatively in 21 patients (24%). All patients had electrophysiologic studies postoperatively and 40% received an implanted cardioverter defibrillator. Of 12 late deaths (16%) at follow-up extending to 8 years, 4 (33%) were due to cardiac causes. Five-year survival was 88%, equivalent to that (83% to 85%) reported for patients with sinus rhythm preoperatively.

Conclusions: Complete myocardial revascularization for ischemic VF/VT yields excellent early and late results; 5-year survival is comparable to that of patients with preoperative sinus rhythm.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 References
 
Ventricular fibrillation or tachycardia (VF/VT) due to myocardial ischemia is a common cause of sudden cardiac death. Definitive treatment includes myocardial revascularization followed by electrophysiologic studies and implantation of a cardioverter defibrillator (ICD) in patients with a high propensity for recurrent VT/VF [1]. Surgical revascularization has been shown to reduce recurrent VF/VT episodes [2, 3], with significant clinical benefit [4], but it is not known whether this benefit is preserved in the long-term, as has been suggested by case series [5].

To assess the early results and late survival after surgical revascularization in patients presenting with VF/VT and coronary artery disease, we conducted a review at our institution of all consecutive coronary artery bypass graft surgery patients who had a history of preoperative VF/VT.


   Patients and Methods
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 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 References
 
We identified all patients who underwent coronary artery bypass graft surgery and had a history of VF/VT, including in- and out-of-hospital cardiac arrests, from January 1999 through January 2007, from the cardiothoracic surgery database of our institution. Preoperative, operative, and postoperative data such as demographic information, presenting symptoms and clinical signs, comorbidities, results of electrocardiograhy, coronary angiography, echocardiography and electrophysiologic studies, details of operative procedures, and postoperative records including heart rhythm at discharge were retrieved. The Medical and Ethics Committee of our institution waived patient consent and approved the use of patient clinical data for this study.

For all survivors, active follow-up was conducted by repeat hospital visit at 6 to 8 weeks postoperatively, and further data were obtained from the general practitioners of the patients on the status of patients, causes of death where applicable, and subsequent ICD placement in patients who were discharged without ICD. We reviewed the causes of death for operative and late deaths.

Data analysis was performed using the Statistical Package for the Social Sciences, version 14.0 for Windows, (SPSS, Chicago, Illinois). Categorical variables are reported as percentages and continuous variables as median with the 25th and 75th percentiles as interquartile range (IQR). The Kaplan-Meier method was used to estimate late survival. Determinants of late death were identified using the Cox proportional regression model, constructed with all the variables listed in Table 1. A two-sided p value of less than 0.05 was considered significant.


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  		Table 1 Clinical Profile and Operative Outcome for Patients Undergoing Coronary Artery Bypass Graft Surgery for Ventricular Fibrillation or Tachycardia Due to Myocardial Ischemia
 

   Results
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 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 References
 
The median age of the 93 patients was 66 years (range, 44 to 88), and the majority were male. Most of the patients had mild angina and were receiving antianginal medications. Ventricular fibrillation or tachycardia occurred after diagnosed myocardial infarction in 51 patients, was induced by exercise testing in 26, and was the cause of resuscitated out-of-hospital cardiac arrest in 15 patients. One patient had unstable angina with numerous episodes of self-terminating ventricular fibrillation/tachycardia in hospital before surgery. The patients with postinfarct VF/VT and out-of-hospital cardiac arrest were transferred for emergent or urgent surgical revascularization. Most of the patients with exercise-induced VF/VT had surgery electively within 3 months. All the patients were receiving antiarrhythmic medications and an ICD was implanted preoperatively in 3 patients.

Coronary angiography demonstrated double- and triple-vessel disease in the vast majority of patients, as shown in Table 1, with other patient characteristics. Prior myocardial infarction, controlled heart failure, and impaired left ventricular systolic function (ejection fraction less than 0.30 in 23% and less than 0.50 in 35%) was prevalent among the patients. Three patients each had mechanical ventilation and intra-aortic balloon pump counterpulsation before surgery; and in 30% of patients, intravenous nitrate was continued till surgery. The coronary territory most frequently affected by significant stenoses (> 50%) was the left anterior descending artery (n = 86, 92%). The circumflex and right coronary arteries were involved in 65 patients (70%) and 64 patients (69%), respectively.

All the ischemic territories received at least one bypass graft. The left internal thoracic artery was used in 73 patients (78%), with a second arterial graft in 4 patients (right internal thoracic artery in 2 and left radial artery in 2). Coronary artery bypass grafting was combined with aortic valve replacement in 5 (5%), left ventricular pseudoaneurysm repair in 3, and repair of ischemic mitral regurgitation in 2 patients. The mean number of diseased vessels was 2.6, and corresponded to the average number of grafts performed (2.5). In most of the patients, surgery was done urgently or emergently using cardiopulmonary bypass; 6 patients had off-pump coronary artery bypass grafting. Recurrent VF/VT was observed during the early postoperative period in 21 patients (24%). Neurologic complications included permanent stroke in 1 patient that lead to death, and reversible ischemic neurologic deficit in 3 patients.

The operative mortality was 6.5% (n = 6). Two patients each died from cardiac and respiratory causes, and 1 each from neurologic and ischemic bowel complications. The operative deaths included 2 of the 3 patients who had an ICD preoperatively. Before hospital discharge, all patients excluding 1 with preoperative ICD (n = 86) underwent electrophysiologic study, and 34 (40%) received an ICD. Oral anti-arrhythmic drugs were continued for all patients for 6 to 8 weeks, and then discontinued for patients who did not have inducible ventricular arrhythmia postoperatively and therefore did not receive an ICD.

At follow-up (median, 3 years; maximum, 8), there were 12 late deaths (16%), predominantly from noncardiac causes (n = 8, 67%). One patient underwent a reoperation 6 years after coronary artery bypass graft surgery and received an aortic valve replacement with a single bypass graft to a coronary territory not grafted at the initial operation. The determinants of late mortality were history of myocardial infarction (hazard ratio [HR] 3.77; 95% confidence interval [CI]: 1.20 to 11.85, p = 0.02), peripheral vascular disease (HR 10.01; 95% CI: 2.11 to 47.45, p = 0.004), and aprotinin use (HR 5.46; 95% CI: 21.71 to 17.46, p = 0.004). The Kaplan-Meier estimated median survival was 8 years (95% CI: 4.6 to 11.2), and the 1- and 5-year survival rates were 92% and 88%, respectively (Fig 1).


Figure 1
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  		Fig 1. Kaplan-Meier survival curve of patients who underwent surgical revascularization with or without implantable cardioverter defibrillator for ischemic ventricular fibrillation/tachycardia.

 

   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
References
 
Ventricular fibrillation or tachycardia is a potentially fatal complication of ischemic heart disease that has been reported by early studies with short follow-up, to continue to threaten late survival even after definitive treatment [1, 6]. The magnitude of the clinical benefit maintained in the long term after surgical revascularization for ischemic VF/VT arrest is, therefore, uncertain. The present study shows that for patients who suffer ischemic VF/VT, with or without near death experience, surgical revascularization with electrophysiologic-guided ICD placement leads to an excellent early and late survival. The observed operative mortality of 6.5% was less than the median EuroSCORE (European System for Cardiac Operative Risk Evaluation) predicted mortality of 9% (range, 4% to 15%) in this very sick group of patients. The 5-year survival of 88% compares well with the 83% to 85% reported in patients with normal sinus rhythm after coronary artery bypass graft surgery [7, 8]. In a previous study of patients with coronary artery disease and coexisting atrial fibrillation conducted at the Mayo Clinic [7], a direct correlation was established between unablated atrial fibrillation and a substantial reduction in survival after isolated coronary artery bypass grafting among patients receiving optimal medical therapy postoperatively. That study identified preoperative atrial fibrillation as a marker and risk factor for late major adverse cardiac and cerebrovascular events. Ventricular tachyarrhythmia associated with coronary artery disease does not appear to have a similar effect on survival after coronary artery bypass grafting. Unlike the atrial arrhythmias, preoperative VF/VT in these patients due to ischemia-induced electrical instability [9, 10] is reversed or controlled by surgical revascularization and ICD placement.

This study also highlights the importance of complete myocardial revascularization in patients with VF/VT due to ischemic heart disease. We believe that the benefit of surgical revascularization is maximized by complete restoration of myocardial blood flow, which is a potential advantage over nonsurgical revascularization in the setting of multivessel disease. Also, the proven durability of surgical revascularization secures the preservation of this benefit over a longer period.

Recurrent VF/VT can occur in the early postoperative period after coronary artery bypass grafting for several reasons, including biochemical derangement and exogenous inotropic overdrive in patients with impaired ventricular function [11], hence preemptive perioperative antiarrhythmic therapy is vital. Postoperative electrophysiologic study identifies the subset of patients with a proclivity to repeat VF/VT [11–14] for ICD placement. We do not routinely implant ICD at the time of surgery, as myocardial revascularization is curative in some patients with ischemic VF/VT.

In this study, we have not investigated late episodes of recurrent VT/VF by analyzing shocks delivered by the ICD, and hence could not determine with any certainty the risk of late recurrent VF/VT in patients with postrevascularization inducible ventricular arrhythmia and its contribution to the late cardiac deaths. However, the prognostic benefit of surgical revascularization with electrophysiologic-guided ICD placement in terms of prevention of sudden cardiac death is reflected in the excellent 5-year survival.

In conclusion, patients with coronary artery disease presenting with VF/VT, including survivors of sudden cardiac death, derive prognostic benefit from complete surgical revascularization and electrophysiologic-guided ICD placement. Late survival is comparable with that of patients in normal sinus rhythm preoperatively.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 References
 

  1. Kaiser GA, Ghahramani A, Bolooki H, et al. Role of coronary artery surgery in patients surviving unexpected cardiac arrest Surgery 1975;78:749-754.[Medline]
  2. Autschbach R, Falk V, Gonska BD, Dalichau H. The effect of coronary bypass graft surgery for the prevention of sudden cardiac death: recurrent episodes after ICD implantation and review of literature Pacing Clin Electrophysiol 1994;17:552-558.[Medline]
  3. Every NR, Fahrenbruch CE, Hallstrom AP, Weaver WD, Cobb LA. Influence of coronary bypass surgery on subsequent outcome of patients resuscitated from out of hospital cardiac arrest J Am Coll Cardiol 1992;19:1435-1439.[Abstract]
  4. Cook JR, Rizo-Patron C, Curtis AB, et al. Effect of surgical revascularization in patients with coronary artery disease and ventricular tachycardia or fibrillation in the Antiarrhythmics Versus Implantable Defibrillators (AVID) registry Am Heart J 2002;143:821-826.[Medline]
  5. Rasmussen K, Lunde PI, Lie M. Coronary bypass surgery in exercise-induced ventricular tachycardia Eur Heart J 1987;8:444-448.[Abstract/Free Full Text]
  6. Lessmeier TJ, Lehmann MH, Steinman RT, et al. Implantable cardioverter-defibrillator therapy in 300 patients with coronary artery disease presenting exclusively with ventricular fibrillation Am Heart J 1994;128:211-218.[Medline]
  7. Ngaage DL, Schaff HV, Mullany CJ, et al. Does preoperative atrial fibrillation influence early and late outcomes of coronary artery bypass grafting? J Thorac Cardiovasc Surg 2007;133:182-189.[Abstract/Free Full Text]
  8. Quader MA, McCarthy PM, Gillinov AM, et al. Does preoperative atrial fibrillation reduce survival after coronary artery bypass grafting? Ann Thorac Surg 2004;77:1514-1524.[Abstract/Free Full Text]
  9. Carnendran L, Steinberg JS. Does an open infarct-related artery after myocardial infarction improve electrical stability? Prog Cardiovasc Dis 2000;42:439-454.[Medline]
  10. Hillis LD, Cigarroa JE, Lange RA. Late revascularization reduces mortality in survivors of myocardial infarction Cardiol Rev 1999;7:144-148.[Medline]
  11. Kaul TK, Fields BL, Riggins LS, Wyatt DA, Jones CR. Ventricular arrhythmia following successful myocardial revascularization: incidence, predictors and prevention Eur J Cardiothorac Surg 1998;13:629-636.[Medline]
  12. Kron IL, Lerman BB, Haines DE, Flanagan TL, DiMarco JP. Coronary artery bypass grafting in patients with ventricular fibrillation Ann Thorac Surg 1989;48:85-89.[Abstract]
  13. Mangi AA, Boeve TJ, Vlahakes GJ, et al. Surgical coronary revascularization and antiarrhythmic therapy in survivors of out-of-hospital cardiac arrest Ann Thorac Surg 2002;74:1510-1516.[Abstract/Free Full Text]
  14. Manolis AS, Rastegar H, Payne D, Cleveland R, Estes III NA. Surgical therapy for drug-refractory ventricular tachycardia: results with mapping-guided subendocardial resection J Am Coll Cardiol 1989;14:199-208.[Abstract]

Related Article

Invited Commentary
Abeel A. Mangi
Ann. Thorac. Surg. 2008 85: 1281-1282. [Extract] [Full Text] [PDF]



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A. A. Mangi
Invited Commentary
Ann. Thorac. Surg., April 1, 2008; 85(4): 1281 - 1282.
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