Effects of coronary artery bypass grafting on ventricular arrhythmias: results with electrophysiological testing and long-term follow-up

Catheter ablation for ventricular tachycardia: indications and techniques

Ventricular tachycardia (VT) may be secondary to many different underlying pathophysiologies. The nature of the underlying disorder determines amenability to catheter ablation, thus, dictating the circumstances under which it should be undertaken. The differing substrates also influence the choice of techniques that are used. The most intensively studied clinical subgroup of VT is re-entrant VT in the setting of ischemic heart disease. The approach to ablation in such patients is discussed in detail. Subsequent discussion focuses on other clinically encountered varieties of VT and the ablation methods used in each individual disease state.

Quantitative tissue characterization of infarct core and border zone in patients with ischemic cardiomyopathy by magnetic resonance is associated with future cardiovascular events

OBJECTIVES

This study evaluates how characterization of tissue heterogeneity of myocardial infarction by cardiovascular magnetic resonance (CMR) is associated with cardiovascular events (CVE) in patients with ischemic cardiomyopathy (ICM).

BACKGROUND

Prior studies demonstrated that the quantification of myocardial scar volume by CMR is superior to left ventricular end-diastolic volume, left ventricular end-systolic volume, and left ventricular ejection fraction (LVEF) in predicting future CVE in ICM patients. Evaluation of infarct heterogeneity by measuring infarct core and border zones through CMR might have a higher association with CVE.

METHODS

Seventy patients (mean LVEF: 25 +/- 11%) considered for revascularization or medical management +/- implantable cardiac defibrillator were enrolled. A 1.5-T GE MRI (Signa, GE Healthcare, Milwaukee, Wisconsin) was used to acquire cine and delayed enhancement images. The patients' core and border zones of infarcted myocardium were analyzed and followed for CVE.

RESULTS

Larger infarct border zone and its percentage of myocardium were found in the 29 patients (41%) who had CVE (median 13.3 g [interquartile range (IQR) 8.4 to 25.1 g] vs. 8.0 g [IQR 3.0 to 14.5 g], p = 0.02 and 7.8% [IQR 4.9% to 17.0%] vs. 4.1% [IQR 1.9% to 9.3%], p = 0.02, respectively). The core infarct zone and its percentage of myocardium, left ventricular end-diastolic volume, left ventricular end-systolic volume, and LVEF were not statistically significant. Sub-analysis of the medical management and revascularization patients with CVE demonstrated that the medically managed patients had a larger border zone, whereas there was no difference between border and core zones in the revascularization group (p < 0.05).

CONCLUSIONS

Quantification of core and border zones and their percentages of myocardium through CMR is associated with future CVE and might assist in the management of patients with ICM.

Will imaging assist in the selection of patients with heart failure for an ICD?

Sudden cardiac death remains the leading cause of death in the U.S. A left ventricular ejection fraction (LVEF)<30% to 35% identifies a population of patients at increased risk for sudden cardiac death. Once identified, an implantable cardioverter-defibrillator (ICD) is effective in reducing the occurrence of sudden cardiac death. Yet in a substantial proportion of patients who receive an ICD based on reduced LVEF, the device never delivers therapy. Furthermore, the majority of patients who die suddenly do not qualify for ICD placement under current LVEF-based criteria in the guidelines. This review considers the potential role of cardiac imaging in improving the selection of patients most likely to benefit from an ICD. The presence of myocardial scar and/or unrevascularized myocardial ischemia provides an important substrate for the occurrence of potentially fatal ventricular arrhythmias. The presence of clinical heart failure further increases the risk of ventricular arrhythmia. The sympathetic nervous system provides an important trigger for major arrhythmic events, both through global overactivity and through regional heterogeneity of sympathetic activity. A mismatch of myocardial perfusion and innervation may pose a particularly great risk. Imaging modalities provide unique opportunities to investigate the anatomic and pathophysiologic substrates, as well as the triggering effects of cardiac sympathetic innervation. Combining imaging and electrophysiologic modalities offers promise for improved accuracy in future selection of patients with heart failure for ICD placement.

Validation of a decision support tool for the evaluation of cardiac arrest victims

BACKGROUND

There is currently no well-accepted model for early and accurate prediction of neurologic and vital outcomes after cardiac arrest. Recent studies indicate that individuals with acute myocardial ischemia as the etiology for the arrest may benefit from early revascularization.

HYPOTHESIS

This study was undertaken to examine whether the cardiac arrest score is valid for predicting outcomes upon arrival at the emergency department.

METHODS

We previously developed a cardiac arrest score based on time to return of spontaneous circulation, initial systolic blood pressure, and level of neurologic alertness in 127 patients (derivation set). This score was prospectively applied to 62 patients with similar clinical profiles (validation set). Utility of the score was evaluated by the area under the receiver operator characteristic curves (C) for both sets. Consistency was measured by using the alpha statistic applied to the cumulative survival at each ascending level of the score.

RESULTS

The derivation and validation sets were similar with respect to baseline characteristics and proportions at each level of score. The survival to discharge was 41.7 and 53.2% for the two sets, respectively. The value of C was 0.89 +/- 0.03 and 0.93 +/- 0.03 for neurologic recovery and 0.81 +/- 0.04 and 0.92 +/- 0.04 for survival to discharge in the two sets, respectively. The level of agreement between the sets across the levels of the score was 0.98 and 0.99 (both p < 0.0001) for the two outcomes.

CONCLUSIONS

The cardiac arrest score is a valid decision support tool in the evaluation of cardiac arrest victims. Patients with the most favorable scores may be considered for early angiography and revascularization if myocardial ischemia is the etiology of the arrest.

Quantitative characterization of myocardial infarction by cardiovascular magnetic resonance predicts future cardiovascular events in patients with ischemic cardiomyopathy

BACKGROUND

Cardiovascular magnetic resonance (CMR) can provide quantitative data of the myocardial tissue utilizing high spatial and temporal resolution along with exquisite tissue contrast. Previous studies have correlated myocardial scar tissue with the occurrence of ventricular arrhythmia. This study was conducted to evaluate whether characterization of myocardial infarction by CMR can predict cardiovascular events in patients with ischemic cardiomyopathy (ICM).

RESULTS

We consecutively studied 86 patients with ICM (LVEF < 50%, mean LVEF: 26 +/- 12%) with CMR before revascularization or medication therapy +/- implantable cardiac defibrillator, determined the amount of myocardial scar, and followed for development of cardiovascular events. Thirty-three patients (38%) had cardiovascular events (mean follow-up: 20 +/- 16 months). Patients who developed cardiovascular events had larger scar volume and scar percentage of the myocardium than those who did not develop cardiovascular events (16.8 +/- 12.4 cm3 vs. 11.7 +/- 12.6 cm3, p = 0.023 and 10.2 +/- 6.9% vs. 7.2 +/- 6.7%, p = 0.037, respectively). There were no significant differences in LVEDV, LVESV and LVEF between the patients with and without cardiovascular events (231 +/- 76 ml vs. 230 +/- 88 ml; 180 +/- 73 ml vs. 175 +/- 90 ml; and 25 +/- 10% vs. 27 +/- 13%, respectively).

CONCLUSION

Quantification of the scar volume and scar percentage by CMR is superior to LVEDV, LVESV, and LVEF in prognosticating the future likelihood of the development of cardiovascular events in patients with ICM.

[Coronary artery disease--relevance of total coronary revascularization on the incidence of malignant arrhythmias]

Myocardial ischemia induces redistribution of different ions (H(+), K(+), Na(+), Ca(++)) across the cardiomyocyte membrane, as well as the loss of intracellular ATP content. This results in changes in the electrical properties including shortening of the action potential, appearance of delayed afterpotentials, and a modified refractoriness of the cardiomyocyte. These changes may induce or support malignant cardiac arrhythmias. Supersensitivity of sympathetic denervated myocardium may further support the electrical instability of ischemic myocardium.Virtues of studies indicate that patients with coronary artery disease who develop complex arrhythmias during or after exercise bear a substantially increased risk for sudden cardiac death. Other studies report about arrhythmic stabilization and reduced mortality if patients with reversible myocardial ischemia receive complete revascularization. However, none of these studies is without methodological flaws. Due to the lack of methodologically sound studies in sufficiently large patient cohorts, the question whether complete coronary revascularisation improves the prognosis of patients with coronary artery disease and which strategy (medical, interventional, or surgical) warrants the best outcomes remains open.

Outcomes after ventricular fibrillation out-of-hospital cardiac arrest: expanding the chain of survival

Coronary heart disease is the most common cause of death in the United States, with ventricular fibrillation (VF) the most common initial rhythm when cardiac disease causes arrest. Survival after VF out-of-hospital cardiac arrest (OHCA) depends on a sequence of events called the chain of survival, which Includes rapid access to emergency medical services, cardiopulmonary resuscitation, defibrillation, and advanced care. Because of widespread implementation of defibrillation programs, more patients survive VF OHCAs, making subsequent care of these patients important. Early hospitalization must focus on potential neurologic injury and therapy targeted at the underlying cardiac disease and antiarrhythmic therapy for long-term secondary prevention of sudden death. Attention to certain cohorts who are at high risk despite their underlying disease, such as women and elderly patients, is necessary. These cohorts may have the greatest response to short-term and long-term therapies for cardiac rehabilitation. With these approaches, long-term survival and quality of life after VF OHCA are favorable. Broadening the focus of the chain of survival to include in-hospital and long-term care will further improve favorable outcomes achieved in an early defibrillation program.

Impact of Viability, Ischemia, Scar Tissue, and Revascularization on Outcome After Aborted Sudden Death

Background— Survivors of aborted sudden death attributable to ventricular arrhythmias in the presence of coronary artery disease are at risk for recurrences. The substrate underlying these arrhythmias is not clear, and therefore the relation between ischemia, viability, scar tissue (and revascularization), and the incidence of ventricular arrhythmias (and survival) was studied over up to 3 years.

Methods and Results— One hundred fifty-three survivors of sudden death underwent stress-rest perfusion imaging. Patients with ischemic/viable myocardium (n=73) were revascularized if possible. Final antiarrhythmic therapy was based on the outcome of electrophysiological testing or left ventricular ejection fraction (LVEF). Implantation of a defibrillator was performed in 112 (72%) patients. During 3-year follow-up, 15 cardiac deaths occurred and 42 (29%) patients had recurrent ventricular arrhythmias. Patients with events (death or recurrence) exhibited more often a severely depressed LVEF (≤30%), more extensive scar tissue, and less ischemic/viable myocardium on perfusion imaging and less frequently underwent revascularization. Multivariate analysis identified extensive scar tissue and LVEF ≤30% as the only predictors of death/recurrent ventricular arrhythmias.

Conclusions— In patients with aborted sudden death, extensive scar tissue and severely depressed LVEF are the only predictors of death or recurrent ventricular arrhythmias. These patients should be considered for implantation of a defibrillator.

Impact of percutaneous coronary intervention or coronary artery bypass grafting on outcome after nonfatal cardiac arrest outside the hospital

Survivors of cardiac arrest due to ventricular arrhythmias are at risk for recurrent events. The role of revascularization in secondary prevention for survivors of cardiac arrest has been addressed in various studies with conflicting results. A total of 142 survivors of cardiac arrest with coronary artery disease were evaluated according to a standardized protocol, including 2-dimensional echocardiography, myocardial perfusion scintigraphy, coronary angiography, and electrophysiologic testing. Revascularization of scintigraphically documented ischemic myocardial regions was performed in 44 patients (31%). Final therapy was based on the results of electrophysiologic testing. Four-year survival rates were 100% for revascularized noninducible patients, 84% for revascularized inducible patients, 91% for nonrevascularized noninducible patients, and 72% for nonrevascularized inducible patients. Only 1 patient (<1% of study population) died suddenly. Recurrences were much more frequent in patients without revascularization (38% vs 7%, p <0.001) and the recurrence rate was 0% in the revascularized noninducible patients. Thus, revascularization of ischemically jeopardized myocardium in survivors of cardiac arrest resulted in excellent survival; moreover, in absence of inducible ventricular arrhythmias, the recurrence rate was 0%. Systematic evaluation of survivors of cardiac arrest due to ventricular arrhythmias allows risk stratification and guidance of subsequent antiarrhythmic therapy.

[Role of coronary artery revascularization and aneurysmectomy in ventricular arrhythmias in the chronic phase of myocardial infarction]

INTRODUCTION AND OBJECTIVES

The influence of coronary artery revascularization on the control of ventricular arrhythmias in patients with chronic myocardial infarction is uncertain. However, ablation of the arrhythmogenic circuit in these patients by aneurysm resection is useful for controlling ventricular arrhythmias. We made a prospective analysis of our clinical strategy in patients who were candidates for coronary artery revascularization and/or aneurysmectomy to determine its influence on the recurrence of ventricular arrhythmias.

PATIENTS AND METHOD

Prospective study of 17 consecutive patients with chronic myocardial infarction and ventricular arrhythmias unrelated with an acute ischemic event, who had coronary artery disease and/or ventricular aneurysm susceptible to aggressive treatment. We evaluated our clinical strategy and the recurrence of ventricular arrhythmias during a mean follow-up period of 33.64 months.

RESULTS

Two groups of patients were studied: patients with ventricular aneurysm (group I: 12 patients) and patients without ventricular aneurysm (group II: 5 patients). Seven patients of group I underwent endoaneurysmorrhaphy and endocardial resection (4 of these patients had associated revascularization procedures). Three patients were not candidates for aneurysmectomy or revascularization procedures. Two patients underwent only revascularization procedures. All the patients in group II were revascularized. The patients who underwent aneurysmectomy did not have recurrence of arrhythmias. In 5 of the 6 patients who underwent programmed electrophysiological stimulation after aneurysmectomy, no sustained arrhythmia could be induced. Patients who were only revascularized had a high rate of recurrence of ventricular arrhythmias (57%), which were inducible after revascularization.

CONCLUSION

Aneurysmectomy and endocardial resection constituted, in our experience, an effective tool for controlling ventricular arrhythmias associated with left ventricular aneurysm. Coronary artery revascularization in patients with ventricular arrhythmias and chronic myocardial infarction probably does not prevent the recurrence of ventricular arrhythmias.

Effect of surgical revascularization in patients with coronary artery disease and ventricular tachycardia or fibrillation in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Registry

BACKGROUND

Patients who undergo resuscitation from near-fatal ventricular arrhythmias often have significant coronary artery disease, and revascularization has been shown to reduce myocardial ischemia and cardiac arrest episodes in this patient population. The magnitude of benefit attributed to revascularization has varied by study, and the use of adjunct implantable cardioverter defibrillator (ICD) therapy has not been well-characterized.

METHODS AND RESULTS

The Antiarrhythmics Versus Implantable Defibrillators (AVID) registry included 3117 patients with life-threatening ventricular arrhythmias, of whom 2321 (77%) had documented coronary artery disease and 281 (17%) underwent a coronary artery bypass grafting revascularization procedure after the index event. Patients who underwent a revascularization procedure were younger, had a lower incidence rate of prior myocardial infarction and ventricular arrhythmia, had a higher left ventricular ejection fraction, had less congestive heart failure, and were more likely to have had ventricular fibrillation as the presenting arrhythmia. Patients who underwent revascularization had a better survival rate than did those who did not undergo such a procedure after the index event, and adjustment for differing baseline patient covariates did not alter the relative survival rate benefit. Further, ICD implantation offered a similar survival rate advantage to those patients in the AVID registry with coronary artery disease independent of revascularization.

CONCLUSION

Coronary revascularization in the AVID registry patients with coronary artery disease effected a survival rate benefit that was not attributable to differences in baseline patient characteristics. The benefit of ICD on patient survival rate was not attenuated by a revascularization procedure.

Precordial QT dispersion does not predict inducibility of ventricular tachyarrhythmias at post-revascularization electrophysiologic study

OBJECTIVES

We tested the hypothesis that revascularization would decrease QT interval dispersion and that QT interval dispersion would predict the outcome of the electrophysiologic study following revascularization.

BACKGROUND

QT interval dispersion may be a measure of the inhomogeneity of ventricular repolarization. The value of the QT interval dispersion for predicting inducibility of ventricular tachyarrhythmias (VT) during electrophysiologic studies after coronary artery revascularization in patients with hemodynamically significant VT is unknown.

METHODS AND RESULTS

QT interval dispersions were measured from electrocardiograms recorded before and after coronary artery revascularization, but before an electrophysiologic study during the same hospitalization. Fifty-six patients (93% male, 65.1 +/- 9.6 years) were studied. QT interval dispersion decreased significantly following revascularization from 69 +/- 31 ms to 53 +/- 23 ms (p=0.002). Inducibility of VT could not be predicted by the QT interval dispersion following revascularization (50 +/- 30 ms in patients with VT induced vs. 58 +/- 25 ms in patients without VT induced at electrophysiologic study; p=0.2). The change in QT interval dispersion with revascularization (-15 +/- 33 ms vs. -17 +/- 46 ms; p=0.9) could not predict VT inducibility. Actuarial survival after 80 months follow-up was similar in the patients in whom VT was induced (82%) and those patients in whom VT was not induced (83%; p=NS).

CONCLUSIONS

Coronary artery revascularization decreased QT interval dispersion in patients with hemodynamically significant VT, but QT interval dispersion was not predictive of inducibility of VT at follow-up electrophysiologic study. Actuarial survival was similar in patients in whom VT was induced and patients in whom VT was not induced.

Coronary artery revascularization in patients with sustained ventricular arrhythmias in the chronic phase of a myocardial infarction: effects on the electrophysiologic substrate and outcome

OBJECTIVES

The objective of this study was to analyze the influence of coronary artery revascularization in patients with ventricular arrhythmias.

BACKGROUND

Coronary artery revascularization is an effective treatment for myocardial ischemia; however, its effect on ventricular arrhythmias not related to an acute ischemic event has not been carefully studied.

METHODS

Sixty-four patients (58 men, mean age 65 +/- 8 years old) with prior myocardial infarction, spontaneous ventricular arrhythmias not related to an acute ischemic event (55 ventricular tachycardia, 9 ventricular fibrillation) and coronary lesions requiring revascularization were studied prospectively. Electrophysiological study was performed before and after revascularization, and events during follow-up were analyzed.

RESULTS

At initial study 61 patients were inducible into sustained ventricular arrhythmias. After revascularization, in 62 survivors, 52 out of 59 patients previously inducible were still inducible (group A), and 10 patients were noninducible (group B). No differences were found in clinical, hemodynamic, therapeutic and electrophysiological characteristics between both groups. During 32 +/- 26 months follow-up, 28/52 patients in group A (54%) and 4/10 patients in group B (40%) had arrhythmic events (p = 0.46). An ejection fraction <30% predicted recurrent arrhythmic events (p = 0.02), but not the presence of demonstrable ischemia before revascularization (p = 0.42), amiodarone (p = 0.69) or beta-adrenergic blocking agent therapy (p = 0.53). Total mortality was 10% in both groups.

CONCLUSIONS

In patients with ventricular arrhythmias in the chronic phase of myocardial infarction, probability of recurrence is high despite coronary artery revascularization, but mortality is low if combined with appropriate antiarrhythmic therapy. Recurrences are related to the presence of a low ejection fraction but not to demonstrable ischemia before revascularization, amiodarone or beta-blocker therapy nor are they the results of electrophysiological testing after revascularization.

Coronary artery bypass grafting and defibrillator implantation in patients with ventricular tachyarrhythmias and ischemic heart disease

In patients with sustained ventricular tachyarrhythmias and myocardial ischemia due to multivessel coronary artery disease, it remains unclear whether revascularization is enough to control the arrhythmias or whether additional implantation of a defibrillator is indicated. We therefore reviewed our clinical strategy of performing both bypass surgery and implantation of a defibrillator in patients with syncopal ventricular tachycardia or fibrillation and significant multivessel coronary artery disease. We retrospectively reviewed the outcome of 18 patients with malignant ventricular tachyarrhythmias, significant multivessel coronary artery disease, and signs of myocardial ischemia who underwent both bypass surgery and defibrillator implantation. Data on these patients were compared to data from 232 other defibrillator patients with respect to baseline clinical variables, cardiac events, and mortality during follow-up. Except for underlying pathology, no other important differences in baseline characteristics were noted between the study patients and the other defibrillator patients. The cumulative occurrence of shocks during follow-up was comparable in both groups (66% vs 67%). The cumulative survival from all-cause mortality was 94% in the study patients and 78% in the others (P = NS). Pre- and postoperative electrophysiological testing was not useful to predict arrhythmia recurrences. In this population of patients with ventricular tachyarrhythmias and ischemia due to multivessel coronary artery disease, bypass surgery alone would not have prevented recurrences of arrhythmias. An excellent survival and a high incidence of shocks after both bypass surgery and defibrillator implantation were observed.

Evaluation of coronary revascularization to prevent tachycardia recurrences in survivors of ventricular fibrillation

Long-term follow-up of 29 consecutive survivors of ventricular fibrillation who underwent revascularization demonstrated that recurrent arrhythmics events were common. Because revascularization alone does not prevent arrhythmia recurrence, treatment with an implantable defibrillator should be considered in these patients.

[Current indications for implantable automatic defibrillators]

Since the first implantation in man in 1980 implantable cardioverter defibrillator technology has greatly improved and the number of devices implanted has increased considerably in recent years. Non-thoracotomy lead systems and biphasic shocks are now the approach of choice, offering nearly a 100% success rate. This paper version reviews the current indications for the implantation of implantable cardioverter defibrillator and is an upgraded of an article previously published by the Arrhythmia's Section of the Spanish Society of Cardiology. Recommendations for qualification of centres implanting defibrillators and follow up are also addressed.

Prediction of death and neurologic outcome in the emergency department in out-of-hospital cardiac arrest survivors

We reviewed the hospital records of 127 consecutive patients who were resuscitated from cardiac arrest in a retrospective cohort analysis. A cardiac arrest score utilizing time to return of spontaneous circulation, systolic blood pressure at the time of presentation, and initial neurologic exam were calculated. This score was analyzed with 39 other clinical variables for significance with regard to mortality or neurologic survival using multivariate analysis. Combining these variables into a cardiac arrest score (levels 0, 1, 2, 3, from least to most favorable) allowed prediction of neurologic outcomes and mortality from a single variable in an independent fashion (p < 0.0001). Logistic regression models found scores of 0, 1, 2, and 3 predicted in-hospital mortality rates of 90%, 71%, 42%, 18%, and neurologic recovery in 3%, 17%, 57%, and 89%, respectively. The cardiac arrest score was able to predict in-hospital mortality and neurologic outcomes in those who survived to emergency department arrival. This scoring scheme may aide in selection of patients for early aggressive measures, including triage coronary angiography and angioplasty.

Left ventricular aneurysmectomy; comparison between two techniques; early and late results

OBJECTIVE

The aim of the present study was to evaluate early and late results of two different surgical techniques for left ventricular aneurysms repair. The conventional aneurysmectomy and direct closure of the ventricular wall and the endoventricular patch plasty.

METHODS

We retrospectively reviewed 118 patients operated on for postinfarction left ventricular aneurysm from 1981 to 1994. Eighty-seven patients (Group A) were operated upon between 1981 and 1991 with the conventional technique and 31 patients (Group B) between 1992 and 1994 with the endoventricular patch plasty technique. Preoperative clinical, hemodynamic and echocardiographic evaluation with operative procedures and early postoperative results of all patients are reported. We also analyzed results of late clinical and echocardiographic controls of 34 patients of Group A and all patients of Group B after a mean follow-up of 42 and 28 months, respectively.

RESULTS

Mean number of by-pass grafts was 1.9 in Group A and 2.6 in Group B (P = 0.01). The left anterior descending coronary artery was revascularized in 27 patients of Group A (34.6%) and 26 of Group B (89.7%) (P < 0.001); the left internal mammary artery was used in seven patients of Group A (8.9%) and 24 of Group B (82.8%) (P < 0.001). Hospital mortality in Group A was 10.3% (9/87), in Group B there was no hospital mortality (P > 0.05). Thirty-two patients of Group A (36.8%) and 3 of Group B (9.7%) suffered of low cardiac output syndrome (P = 0.01). At late control, improvements observed in NYHA and CCS classes, left ventricular ejection fraction (all P < 0.001 in both groups versus preoperative values) and left ventricular end-diastolic diameter (P > 0.05 in Group A and P < 0.001 in Group B) proved to be statistically higher in patients of Group B.

CONCLUSIONS

Endoventricular patch plasty associated with a complete myocardial revascularization, in particular of the anterior descending coronary, and a larger use of the internal mammary artery, permits, by means of reconstruction of the left ventricular geometry, a better outcome for patients undergoing left ventricular aneurysmectomy.

Does the initial presentation of patients with implantable defibrillator influence the outcome?

The influence of the clinical presentation on the long-term outcome in 213 consecutive patients with ICDs, ECG storage capability, and nonthoracotomy leads, was analyzed. Sixty-six patients presented with cardiac arrest (CA), 81 patients with hemodynamically stable VT, and 66 patients with syncope (SY). Patient characteristics were: mean age CA 62, VT 61, SY 61 years; mean ejection fraction CA 31%, VT 29%, SY 30%; coronary artery disease CA 71%, VT 71%, SY 64% (all P > 0.05 Fisher's exact test); female gender CA 40%, VT 14%, SY 19% (CA vs VT and SY, P < 0.005); inducibility by programmed stimulation CA 50%, VT 84%, SY 61% (VT vs CA and SY, P < 0.001, CA vs SY, P > 0.05). During a mean follow-up of 14.5 months, 29 patients died: CA 12%, VT 14%, SY 9% (P > 0.05). Comparing Kaplan-Meier curves, no difference in the time course of overall mortality was found (log-rank P > 0.05). In the CA, VT, and SY groups, 543, 1,630, and 189 ICD therapies (including antitachycardia pacing, low energy cardioversion, and defibrillation) were observed, respectively. Actuarial analysis showed a shorter interval between implantation and first ICD therapy for VT versus CA and SY (log-rank P < 0.005). Patients presenting with VT experienced earlier and more frequent ICD therapies than patients with CA or SY independent of age, ejection fraction, and heart disease. No difference in overall mortality and time course of fatal events was observed among the three groups.

A patient with syncopal ventricular tachycardia (noninducible on electrophysiologic study) and coronary artery disease

The case of a 63-year-old patient with coronary artery disease presenting with syncopal sustained ventricular tachycardia is reported. He had very poor ventricular function, an extensive myocardial scar, and limited area of reversible ischemia. Coronary angiographic examination showed a left main equivalent coronary artery disease with critical stenosis. Although this patient should theoretically benefit from revascularization, we decided against this due to the high estimated perioperative mortality rate for coronary artery bypass grafting in such a patient. Therefore, we intensively treated myocardial ischemia and pump failure with digoxon, furosemide, dihydralazine, nitrates, and warfarin and prescribed a back-up defibrillator implant.

Late results with concomitant coronary artery bypass grafting and ICD implantation

BACKGROUND

To determine the influence of left ventricular function on the long-term survival of patients with coronary artery disease and lethal ventricular arrhythmias, who undergo concomitant coronary artery bypass grafting (CABG) and implantable cardiovertor defibrillator (ICD) implantation, we studied survival in 54 consecutive patients who underwent CABG and ICD implantation.

METHODS

Group I consisted of 35 patients with left ventricular ejection fraction (LVEF) < or = 35% (mean 25.3 +/- 5.6) and Group II consisted of 19 patients with LVEF > 35% (mean 47.5 +/- 6.6). The two groups were similar with regards to age, gender, clinical presentation, induced arrhythmias, and the number of grafts placed at the time of surgery.

RESULTS

Two in-hospital deaths (3.7%) occurred, both in Group I. During follow-up (42.5 +/- 21.8 months), there were 10 deaths in Group I (1 noncardiac, 1 sudden, and 8 heart failure), and 1 death in Group II (heart failure) (p < 0.04).

CONCLUSIONS

Concomitant CABG and ICD implantation can be performed with an acceptable in-hospital mortality, even in patients with poor left ventricular function. Although freedom from sudden cardiac death remains excellent, overall long-term survival is limited by refractory heart failure, especially in those patients with left ventricular dysfunction at the time of surgery.

Is a baseline electrophysiologic study mandatory for the management of patients with spontaneous, sustained, ventricular tachyarrhythmias?

Should the patient being treated for spontaneous, sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) routinely undergo a baseline, diagnostic, catheter electrophysiologic (EP) study? The potential patient advantages of such a policy include identification of the tachyarrhythmia-initiating episodes of presumed VT or VF, prediction of the subsequent risk of VT/VF recurrences, identification of VT mechanisms amenable to cure by catheter ablation, assessment of the response of a patient's VT to attempts at pace termination, evaluation of the patient's candidacy for some of the approaches to VT/VF therapy selection, and enhancement of our understanding of the mechanisms and therapeutics of VT/VF. Disadvantages of such a policy include patient discomfort, patient risks, and cost. Recognizing that the decision to perform a baseline catheter EP study in a patient with VT/VF must be based on an individualized, patient-based, risk-benefit analysis; this review details each of the advantages and disadvantages of doing so to identify patient populations for whom a baseline catheter EP study is or is not usually indicated.

Ventricular fibrillation and polymorphic ventricular tachycardia with critical coronary artery stenosis: does bypass surgery suffice?

INTRODUCTION

Previous studies have suggested that coronary artery bypass surgery is sufficient to prevent recurrence of sudden death in patients with critical coronary artery stenosis presenting with ventricular fibrillation or polymorphic ventricular tachycardia. We present our experience in patients with one or more episodes of sudden death associated with documented ventricular fibrillation or polymorphic ventricular tachycardia and severe operable coronary artery disease who underwent defibrillator implant at the time of bypass surgery.

METHODS AND RESULTS

Fifty-eight consecutive patients (age 63 +/- 8 years) were included in this study. Eighteen of the 58 patients had no evidence of previous myocardial infarction. The mean ejection fraction was 37 +/- 13%. All patients underwent electrophysiologic study before and after revascularization. At the time of first defibrillator discharge, each patient was reevaluated to exclude the presence of ischemia. The benefits of defibrillator implant were estimated comparing the projected survival based upon defibrillator discharge preceded by syncope or presyncope with survival curves generated including total death and sudden plus cardiac death. After a mean follow-up of 4.6 +/- 2 years, 22 patients received appropriate shocks preceded by syncope or presyncope, and an additional 19 patients received asymptomatic shocks. At 4 years, survival free of total death was 71.2%, and the projected survival was 58.8% (P < 0.05). Multivariate analysis showed that ejection fraction lower than 30% and induction of arrhythmia with one or two extrastimuli (S2, S3) were independent predictors for defibrillator discharge. None of the remaining variables including age, gender, number of bypasses, history of myocardial infarction, and type of arrhythmias induced were predictive for death and occurrence of shocks.

CONCLUSIONS

In patients with ventricular fibrillation and polymorphic ventricular tachycardia, bypass surgery does not protect from recurrence of life-threatening arrhythmias, and, as in our population, defibrillator implant may have significant impact on survival.

Clinical experience with the implantable cardioverter defibrillator

The implantable cardioverter defibrillator has played an increasingly greater role in the management of episodes of sudden cardiac-related death related to ventricular tachycardia or ventricular fibrillation. This study reviews the cases of 142 patients who underwent insertion of an implantable cardioverter defibrillator, 104 who received a device alone (group I) and 38 who underwent insertion of the device in combination with other cardiac surgical procedures (group II). The overall operative mortality was 3.5% and this did not differ between the two groups. The complication rate was higher for group II than for group I patients, and consisted primarily of an increased incidence of atrial arrhythmias (53% versus 13%; p < 0.001). Late complications included three device infections requiring removal of the defibrillator. The late mortality did not differ between the two groups and was primarily related to congestive heart failure. Sudden cardiac-related death was an uncommon late event, with an actuarial freedom from sudden cardiac-related death of 98%, 97%, and 87% at 1, 2, and 5 years, respectively. The morbidity and mortality rate are low in association with the insertion of an implantable cardioverter defibrillator, even when this is combined with other cardiac surgical procedures. Its insertion is also associated with a low subsequent rate of sudden cardiac-related death.

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

Sudden cardiac death (SCD) accounts for at least 50% of the mortality of patients with ischemic heart failure. Ventricular arrhythmias are responsible for most cases of sudden cardiac death. There is some evidence that coronary artery bypass graft (CABG) surgery may reduce the incidence of recurrent episodes of SCD by prevention of myocardial ischemia. To test the hypothesis that CABG surgery is effective in the prevention of SCD, we compared the recordings of implantable cardioverter defibrillators (ICD) in patients who underwent ICD implantation alone (n = 64) or ICD implantation and concomitant CABG surgery respectively (n = 11). All patients had experienced out of hospital cardiac arrest. ICD recordings were obtained every 3 months and the number of recurrent episodes of ventricular tachycardia (VT) for each time period was noted. Three months following ICD implantation patients in the surgically treated group had an average of one episode of VT per patient as compared to 2.7 episodes in the nonsurgical group. This difference was observed during the following months as well. However, at no time (up to 18 months of follow-up) this difference reached statistical significance. There were no deaths in the surgically treated group. Although we could not demonstrate a statistical significant difference between the two groups, there was a tendency in the surgically treated group to have less episodes of recurrent VT than in the medically treated group. We, therefore, conclude that survivors of SCD presenting with multivessel coronary artery disease (CAD) should undergo coronary artery bypass grafting to prevent myocardial ischemia as the triggering event for lethal ventricular arrhythmias.