The effect of coronary bypass graft surgery for the prevention of sudden cardiac death: recurrent episodes after ICD implantation and review of literature

The effect of revascularization on mortality and risk of ventricular arrhythmia in patients with ischemic cardiomyopathy

Background

There is clear evidence that patients with prior myocardial infarction and a reduced ejection fraction benefit from implantation of a cardioverter-defibrillator (ICD). It is unclear whether this benefit is altered by whether or not revascularization is performed prior to ICD implantation.

Methods

This was a retrospective cohort study following patients who underwent ICD implantation from 2002 to 2014. Patients with ischemic cardiomyopathy and either primary or secondary prevention ICDs were selected for inclusion. Using the electronic medical record, cardiac catheterization data, revascularization status (percutaneous coronary intervention or coronary bypass surgery) were recorded. The outcomes were mortality and ventricular arrhythmia.

Results

There were 606 patients included in the analysis. The mean age was 66.3 ± 10.1 years, 11.9% were women, and the mean LVEF was 30.5 ± 12.0, 58.9% had a primary indication for ICD, 82.0% of the cohort had undergone coronary catheterization prior to ICD implantation. In the overall cohort, there were fewer mortality and ventricular arrhythmia events in patients who had undergone prior revascularization. In patients who had an ICD for secondary prevention, revascularization was associated with a decrease in mortality (HR 0.46, 95% CI (0.24, 0.85) p = 0.015), and a trend towards fewer ventricular arrhythmia (HR 0.62, 95% CI (0.38, 1.00) p = 0.051). There was no association between death or ventricular arrhythmia with revascularization in patients with primary prevention ICDs.

Conclusion

Revascularization may be beneficial in preventing recurrent ventricular arrhythmia, and should be considered as adjunctive therapy to ICD implantation to improve cardiovascular outcomes.

Effect of coronary revascularization on long-term clinical outcomes in patients with ischemic cardiomyopathy and recurrent ventricular arrhythmia

BACKGROUND

Patients with ventricular tachycardia (VT) postmyocardial infarction (MI) are a higher risk group with significant morbidity and mortality. We examined the impact of prior coronary revascularization on clinical outcomes in patients with ischemic cardiomyopathy and VT.

METHODS

The VANISH trial randomized 259 patients with prior MI and antiarrhythmic drug-refractory VT to receive escalated medical therapy or catheter ablation. Clinical outcomes were compared according to whether patients have undergone prior revascularization procedures. The primary outcome was a composite of death, appropriate implantable cardiac defibrillator (ICD) shock, or VT storm. The secondary outcomes included elements of the primary outcome, hospitalization, and any ventricular arrhythmia.

RESULTS

190 patients (73%) had prior coronary revascularization. Revascularization group had more men (97% vs 83%; P  =  0.0003) and patients in that group were older (mean age 69.3 ± 7.6 vs 66.7 ± 9.2; P  =  0.04), had more renal insufficiency (22.6% vs 8.7%; P  =  0.01), and were more likely to have an implanted cardiac resynchronization device (23% vs 10%, P  =  0.03) as compared with the nonrevascularized patients. There were no significant differences in baseline medication use. There was a trend toward fewer hospitalizations in the revascularization group (64% vs 77%; P  =  0.07); there were no differences in the individual outcomes of mortality, VT storm, ICD shocks, recurrent MI, or cardiac failure.

CONCLUSIONS

In this cohort of patients with an ischemic cause for VT, a history of prior coronary revascularization was not associated with a reduction in ventricular arrhythmia or mortality.

Five-Year Outcome after Coronary Artery Bypass Surgery in Survivors of Out-of-Hospital Cardiac Arrest

Objective: The aim of this study was to evaluate the role of coronary artery bypass grafting (CABG) in patients with out-of-hospital cardiac arrest (OHCA).

Methods: The immediate and 5-year outcome after CABG of a consecutive series of 48 patients who survived OHCA was compared with those of control patients having had a recent myocardial infarction without ventricular arrhythmias.

Results: All OHCA patients were found to have suffered myocardial infarction-related cardiac arrest. The mean delay from OHCA to CABG was 10.3 ± 13.0 days. Despite not statistically significant, the risk of 30-day postoperative mortality was higher among OHCA patients than control patients (6.3 vs. 0%, p = 0.24, propensity score adjusted analysis: p = 1.00). Cardioverter defibrillator was implanted in two patients who were alive 3.8 and 4.4 years after CABG, respectively. At 5-year, the overall survival rate was 80.7% in OHCA patients and 84.5% in control patients (p = 0.98, propensity score adjusted analysis: p = 0.87), and survival freedom from fatal cardiac event was 86.1% in OHCA patients and 86.5% in control patients (p = 0.61; propensity score adjusted analysis: p = 0.90).

Conclusions: Early and 5-year survival rates after CABG in OHCA patients are excellent even when cardioverter defibrillator is very selectively implanted. The early and intermediate results CABG suggest a confident approach toward surgical revascularization in this critically ill patient population.

Update on cardiac resuscitation for sudden death: International Guidelines 2000 on Resuscitation and Emergency Cardiac Care

Cardiopulmonary resuscitation developed over the past one half century largely from empiric science and consensus opinions and recommendations. Treatment algorithms and protocols were originally developed to summarize existing recommendations for systematic and regimented use by a heterogenous group of health care providers. Now, resuscitation science and health care teams are focusing on major issues and continuing questions as sudden death rates remain undaunted and the population at risk is rapidly increasing. For the first time, the international resuscitation community has developed an international consensus on Guidelines for Resuscitation and Emergency Cardiac Care. More than 400 basic scientists, clinical trial investigators, and educators defined common priority and scientific areas during the Evidence Evaluation International Meeting in 1999. The science of resuscitation and emergency cardiac care was reviewed for evidence-based support in randomized clinical trials. In 2000, this review was used as a foundation to structure international guidelines. The participants from seven resuscitation councils and foundations realized that regional differences in systems may exist, but the underlying science should be the same. Presented in this article are some of the major issues and controversies discussed in adult advanced cardiac life support, primarily focusing on the major problem of prehospital adult cardiac arrest.

Prevention of sudden death in patients with coronary artery disease: do lipid-lowering drugs play a role?

Ventricular arrhythmias are the most common cause of sudden cardiac death in patients with coronary artery disease. Since treatment of hypercholesterolemia in patients with coronary artery disease reduces the risk of major coronary events by about 30%, one could speculate that this treatment could also result in a reduction of arrhythmic episodes in high-risk patients. In this review, the importance of myocardial ischemia as a trigger for ventricular arrhythmias, as well as the available data that suggest a possible effect of anti-ischemic treatments, including lipid-lowering drugs, on these arrhythmias are presented. Also, possible mechanisms and future research to test the hypothesis that lipid-lowering drugs can reduce life-threatening ventricular arrhythmias are discussed.

Surgical coronary revascularization and antiarrhythmic therapy in survivors of out-of-hospital cardiac arrest

BACKGROUND

Patients who survive out-of-hospital cardiac arrest are at high risk for recurrent arrest. Coronary artery bypass grafting (CABG) confers a survival advantage, but it is unclear whether antiarrhythmic drugs or an implanted defibrillator confer added benefit. This study was designed to determine predictors for further treatment, survival, and therapeutic internal cardiac defibrillator (ICD) discharge in this patient population.

METHODS

One hundred and eight patients undergoing CABG after out-of-hospital cardiac arrest were identified over a 12-year period. Case records were retrospectively reviewed. Follow-up was obtained and predictors of outcome events were analyzed.

RESULTS

Fifty-four (50%) patients underwent CABG only. Fifty-four received additional treatment that included ICD placement in 23 (21%), antiarrhythmic medications in 19 (18%), or both in 12 (11%). Predictors of ICD placement included left ventricular ejection fraction (LVEF) less than 40% and perioperative intraaortic balloon counterpulsation. ICD or medical management increased survival in patients with LVEF <40%. Predictors of increased mortality included age >65 years, Cleveland Severity Score >8, and female gender. Predictors of therapeutic ICD discharge included age >65 years, reoperative CABG, LVEF <40%, and positive postoperative electrophysiological (EP) study. No patient with a negative postoperative EP study received an ICD, and none suffered sudden cardiac death during follow-up.

CONCLUSIONS

Patients with coronary artery disease anatomically suitable for CABG who survive an acute out-of-hospital cardiac arrest should undergo EP testing after CABG. Approximately half of these patients are adequately treated by CABG alone. The remainder may benefit from ICD placement or medical antiarrhythmic management.

Factors determining long-term outcomes and survival in patients with coronary artery disease and ventricular tachyarrhythmias: a single center experience

A Single-Center Experience. The influence, after ICD implantation, of concomitant CABG, angioplasty, and other antiischemic therapeutic interventions, like treatment with beta-blockers, on outcome and mortality of patients with VT or VF due to CAD remains uncertain. The univariate and multivariate risks of recurrence of ventricular arrhythmias requiring ICD interventions or death associated with baseline clinical and functional variables were studied in 160 consecutive patients with CAD of whom 30 underwent CABG or angioplasty at < or = 2 weeks before ICD implantation. ICD interventions occurred in 98 (61%) patients over a mean follow-up of 1,065 days. In univariate and multivariate analysis, VT as the presenting arrhythmia was the only clinical factor predictive of recurrences. Treatment with beta-blockers at hospital discharge reduced the probability of recurrences. Kaplan-Meier analysis confirmed the effect of beta-blockers (P < 0.005) and of VT as the presenting arrhythmia (P < 0.01). Overall mortality was 61% (29/160). In multivariate analysis a low ejection fraction (< or = 0.20) and omission of angiotensin-converting enzyme inhibitors at discharge were associated with excess mortality. In Kaplan-Meier analysis, a low ejection fraction (borderline between 0.30 and 0.21, significant < 0.21) was the single predictor of mortality. Revascularization by CABG or angioplasty had no influence on ventricular arrhythmia recurrences or survival. During long-term follow-up, VT as the presenting arrhythmia and the omission of beta-blocker therapy were associated with excess recurrences of ventricular arrhythmias after ICD implantation. In contrast, survival depended primarily on left ventricular function at discharge. Revascularization did not prevent recurrences of arrhythmias and had no significant effect on survival in the small group of patients who underwent CABG or angioplasty.

Intraoperative arrhythmias and tissue damage during transmyocardial laser revascularization

BACKGROUND

Transmyocardial laser revascularization creates transmural channels to improve myocardial perfusion. Different laser sources and ablation modalities have been proposed for transmyocardial laser revascularization. We investigated the incidence of cardiac arrhythmias and laser-tissue interactions during transmyocardial laser revascularization of normal porcine myocardium with three different lasers.

METHODS

We used a continuous-wave, chopped CO2 laser (20 J/pulse, 15 ms/pulse) synchronized with the R wave; a holmium:yttrium aluminum garnet (Ho:YAG) laser (2 J/pulse, 250 micros/pulse, 5 Hz); and a xenon-chloride (excimer, Xe:Cl) laser (35 mJ/pulse, 20 ns/pulse, 30 Hz). Each laser was used 30 times as the sole modality in four consecutive pigs, yielding 120 channels.

RESULTS

The average number of pulses needed to create a channel was 1, 11 +/- 4, and 37 +/- 8 for the CO2, Ho:YAG, and Xe:Cl lasers, respectively. All Ho:YAG and Xe:Cl channels had premature ventricular contractions. Ventricular tachycardia occurred in 70% of the Xe:Cl and 60% of the Ho:YAG channels. Only 36% of the CO2 channels had premature ventricular contractions, and only 3% of the CO2 channels had ventricular tachycardia (p < 0.001 versus Ho:YAG and Xe:Cl). Ho:YAG channels were highly irregular: each had a 0.6-mm-wide central zone surrounded by a ring of coagulation necrosis (diameter, 1.84 +/- 0.67 mm) with effaced cellular architecture in a thin hemorrhagic zone. The Xe:Cl sections exhibited the same patterns on a smaller scale (diameter, 0.74 +/- 0.18 mm). The CO2 channels were straight and well demarcated. The zone of structural and thermal damage extended over half the channel's diameter, measuring 0.52 +/- 0.25 mm.

CONCLUSIONS

During transmyocardial laser revascularization, the CO2 laser synchronized with the R wave is significantly less arrhythmogenic than the Ho:YAG and Xe:Cl lasers not synchronized with the R wave. In addition, the interaction of the CO2 laser with porcine cardiac tissue is significantly less traumatic than that of the Ho:YAG and the Xe:Cl lasers.

Direct operation versus ICD therapy for ischemic ventricular tachycardia

Now that the implantable cardioverter defibrillator is available as a therapeutic option for the management of ventricular tachycardia (VT), some argue that there no longer should be a role for direct surgical intervention for this malignant arrhythmia. Rebuttal of this argument is difficult for the following reasons: (1) there are many patients who are candidates for implantable cardioverter defibrillator therapy but not for direct VT operation, and thus direct comparisons of the two therapies is difficult; (2) implantable cardioverter defibrillator therapy by definition is palliative, but a VT operation is curative in most instances; (3) in many electrophysiologic triage algorithms, implantation of a cardioverter defibrillator and VT operation are employed as alternative, not competitive, therapies, again making direct comparisons difficult; and (4) probably most importantly, there are misconceptions in the literature regarding the risks and benefits of direct VT surgical procedures as they are currently performed. In this brief review, we examine the currently available data on both sides of this argument.

The future of arrhythmia surgery

The future of arrhythmia surgery is discussed in light of the 25 years of historical developments that have led to the present explosion in antiarrhythmic therapies and technologies. The role of the arrhythmia surgeon in these developments is outlined, along with a number of exciting near-term and far-term developments that will continue to revolutionize therapeutic interventions for arrhythmia problems.