Long-term follow-up of survivors of prehospital sudden cardiac death treated with coronary bypass surgery

Employment status 1 year after out-of-hospital cardiac arrest in comatose patients treated with therapeutic hypothermia

BACKGROUND

Therapeutic hypothermia for comatose survivors of out-of-hospital cardiac arrest (OHCA) has improved survival and neurologic outcome. This study focused on return to work 1 year after therapeutic hypothermia.

METHODS

From June 2004 to June 2009, patients between 18 and 65 years of age with OHCA, who were treated with hypothermia from two regions, representing one third of the national population, were identified from the Danish National Patient Registry, and from hospital and ambulance records. The patients' employment status was obtained from the Danish Ministry of Employment.

RESULTS

One hundred thirty-three comatose patients after OHCA treated with hypothermia were identified. One hundred and four (78%) patients were employed, or able to work, at the time of cardiac arrest. This particular group of patients showed significant lower in-hospital mortality compared to the group of patients who were not able to work before cardiac arrest; 13% vs. 48%, respectively (P < 0.001). The workable group had a lower Charlson comorbidity score (P = 0.004), a higher incidence of witnessed cardiac arrest (P = 0.004) and a higher incidence of shockable heart rhythm (P < 0.001). Eighty-seven patients (84%), who were able to work prior to cardiac arrest, survived, and 55 (65%) of these patients were employed or able to work at 1 year follow-up.

CONCLUSION

The majority of patients employed, or able to work prior to OHCA, had returned to work at one year follow-up. Predictors of return to work in comatose patients treated with hypothermia have to be identified in a larger-scale study.

[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.

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.

PAI-I 4G/5G polymorphism and sudden cardiac death in patients with coronary artery disease

The 4G/5G polymorphism of the plasminogen activator inhibitor type I (PAI-I) gene is involved in coronary artery disease (CAD), with the highest risk in 4G/4G homozygotes. The role of PAI-I polymorphism in patients suffering from CAD and history of sudden cardiac death (SCD) has not been addressed yet. We studied the frequency distribution of the PAI-I gene to test the hypothesis that the 4G/4G genotype favors myocardial ischemia and, even in the absence of acute infarction, promotes SCD in patients with CAD.

METHODS

The PAI-I 4G/5G genotypes and PAI-I antigen plasma levels were determined in 97 patients with CAD and a history of SCD treated with an implantable cardioverter defibrillator (ICD) (defibrillator group) comparing to 113 patients with CAD but no history of SCD (control group).

RESULTS

The defibrillator group consisted of significantly more 4G/4G homozygotes and higher PAI-I levels than the control group (44% vs. 24%, 173+/-41 vs. 144+/-49 ng/ml; P<.01). The carriers of 4G allele had a significantly higher risk for SCD (odds ratio (OR) 1.9) with the highest risk in the 4G/4G genotype (OR 3.6, P<.01).

CONCLUSION

These results suggest that the PAI-I 4G/4G genotype is associated with SCD in patients suffering from CAD.

Evaluation and management of cardiac arrhythmias in the elderly

Cardiac arrhythmias are common in elderly patients. Complete evaluation with detection of underlying structural heart disease and comorbidities is necessary. Prognosis is dependent on the presence of underlying heart disease, particularly the degree of ventricular dysfunction and the presence of comorbidities. Long-term prognosis is excellent in patients without underlying heart disease or severe comorbidities. Management and specific drug therapy in elderly patients with arrhythmias need to be individualized in reference to the underlying cardiac disorder, drug side effects, and the patient's comorbidities.

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.

Ventricular arrhythmias in the elderly

Sudden cardiac death (SCD) remains a significant medical problem in the United States. The incidence of SCD increases with advancing age because cardiovascular disease is more prevalent in the elderly. Management of ventricular arrhythmias in the elderly patient is especially challenging because of increased risk of interventional and pharmacologic therapies, altered pharmacokinetics of drugs, and sometimes unclear long-term benefits.

Effect of antithrombotic therapy on risk of sudden coronary death in patients with congestive heart failure

Data from epidemiologic, autopsy, Holter monitoring, and electrophysiologic studies support the hypothesis that acute myocardial ischemia, even in the absence of myocardial infarction, is a critical component of the pathophysiology of sudden coronary death. Acute myocardial ischemia superimposed upon ventricles damaged from previous infarctions has been demonstrated to enhance the generation of lethal ventricular arrhythmias. This is a retrospective analysis of 6,797 participants in the Studies of Left Ventricular Dysfunction prevention and treatment trials. Both univariate and multivariate Cox proportional-hazards modeling were used to study the association of anticoagulant and antiplatelet therapy with the risk for sudden cardiac death. The following covariates were adjusted for in the analysis: age, ejection fraction, gender, atrial fibrillation, diabetes, a history of angina, prior infarction, prior revascularization, and the regular use of beta blockers, diuretics, digoxin, antiarrhythmic agents, or enalapril. The overall incidence of sudden cardiac death per 100 patient-years of follow-up was 2.24%. In multivariate analysis, antiplatelet and anticoagulant monotherapy each remained independently associated with a reduction in the risk of sudden cardiac death: antiplatelet therapy with a 24% reduction (relative risk [RR] 0.76; 95% confidence interval [CI] 0.61-0.95) and antiplatelet monotherapy with a 32% reduction (RR 0.68; 95% CI 0.48-0.96). Thus, in patients with moderate to severe left ventricular systolic dysfunction resulting from coronary artery disease, antiplatelet and anticoagulant therapy are each associated with a reduction in the risk of sudden cardiac death.

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.

Treatment of ventricular arrhythmias in older adults

OBJECTIVE

To review the prognosis and management of ventricular arrhythmias (VA) in persons with and without heart disease with emphasis on older adults.

DATA SOURCES

A computer-assisted search of the English language literature (MEDLINE database) followed by a manual search of the bibliographies of pertinent articles.

STUDY SELECTION

Studies on the prognosis and management of VA in persons with and without heart disease were screened for review. Studies in older people and recent studies were emphasized.

DATA EXTRACTION

Pertinent data were extracted from the reviewed articles. Emphasis was on studies involving the older persons. Relevant articles were reviewed in depth.

DATA SYNTHESIS

Available data about the prognosis and management of VA in persons with and without heart disease, with emphasis on studies involving older people, were summarized.

CONCLUSIONS

VA in older persons without heart disease should not be treated with antiarrhythmic drugs. Class I antiarrhythmic drugs should not be used to treat VA in older persons with heart disease. Beta blockers should be used to treat complex VA in older persons with ischemic or nonischemic heart disease if there are no contraindications to beta blocker therapy. The use of amiodarone in treating complex VA should be reserved for life-threatening ventricular tachyarrhythmias in older persons who cannot tolerate or who do not respond to beta blockers. VA associated with congestive heart failure should be treated with angiotensin converting enzyme inhibitors. If older patients have life-threatening recurrent ventricular tachycardia or ventricular fibrillation resistant to antiarrhythmic drugs, invasive intervention should be performed. The automatic implantable cardioverter-defibrillator is recommended in older patients who have medically refractory sustained ventricular tachycardia or ventricular fibrillation.

Risk and benefit of additional aortocoronary bypass grafting in patients undergoing cardioverter-defibrillator implantation

It is unclear whether additional aortocoronary bypass grafting should be performed in patients who need an automatic implantable cardioverter defibrillator (ICD) in one- or two-step procedures. Therefore we studied the follow-up of 139 patients who underwent epicardial implantation of the cardioverter defibrillator (CD). All patients had coronary artery disease and recurrent ventricular tachycardia or fibrillation. Eighty-nine patients had implantation of the CD without additional surgical approaches (group G1), and 50 patients had concomitant aortocoronary bypass grafting (group G2). Perioperative mortality (within 30 days after CD implant) was 1 (1%) of 89 patients in G1 and 6 (12%) of 50 patients in G2 (p < 0.01). During the mean follow-up of 26 +/- 20 months, sudden death occurred in four (4%) of 89 patients in G1 and two (4%) of 50 patients in G2. Twenty-three (17%) patients died of cardiac failure (18 [20%] patients in G1 and 5 [10%] patients in G2). ICD discharges occurred in 69 (78%) of 89 patients in G1 and in 36 (72%) of 50 patients in G2. The mean incidence of ICD discharges was 23 +/- 69 shocks per patient in G1 and 18 +/- 25 shocks per patient in G2 (p = NS). We conclude that concomitant aortocoronary bypass grafting during CD implantation leads to a higher perioperative mortality. Avoidance of myocardial ischemia does not significantly influence sudden death mortality nor markedly reduce the number of ICD discharges.

Future developments in implantable cardioverter defibrillators: the optimal device

Despite recent therapeutic advances, SCD remains the leading cause of mortality in industralized nations. The most frequent cause of SCD is ventricular tachyarrhythmias in the setting of advanced structural heart disease due to chronic coronary heart disease or idiopathic dilated cardiomyopathy. Although high-risk groups can be prospectively identified, attempts at primary prevention have been largely unsuccessful. Effective treatment strategies for SCD survivors include antiarrhythmic drug therapy guided by programmed stimulation, endocardial resection, and ICDs. Device therapy has proven extremely effective in preventing recurrent sudden death from ventricular tachyarrhythmias. Widespread application of ICD therapy, perhaps even to include members of high-risk populations that have not experienced cardiac arrest, will depend on many factors including the demonstration that device therapy improves total mortality, not just arrhythmia-related mortality, reduction in cost, and improvements in the devices themselves. Some of the important characteristics of the optimal ICD of the future are nonthoracotomy lead placement; subpectoral generator placement; multiprogrammable, tiered therapy; improved diagnostic specificity, whether based on electrogram or hemodynamic-sensing algorithms; improved integration of brady- and tachy-sensing systems; and enhanced electrogram storage capability with trans-telephonic retrieval of electrogram recordings. The creation of this ideal ICD will obviously require continued technological advances; however, given the tremendous improvements realized over the first three generations of ICD systems, optimism for the future seems warranted.

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

Myocardial revascularization was performed in 56 patients with coronary artery disease who presented with ventricular tachycardia (VT) (n = 39) or ventricular fibrillation (n = 17). There were 46 men and 10 women, aged 65 +/- 10 years. Three vessel (n = 42) or left main disease (n = 4) was present in 82%. Left ventricular ejection fraction averaged 36% +/- 11%. Electrophysiological studies were performed preoperatively in all patients; 50 (89%) had inducible ventricular arrhythmias. Sustained monomorphic VT was induced in 40 patients (cycle length 284 +/- 61 msec). Reproducible symptomatic nonsustained VT was induced in four patients and ventricular fibrillation in six patients, while six patients had no inducible arrhythmia. Preoperatively the patients with inducible VT failed 3.3 +/- 1.2 drug trials during electrophysiological studies. In addition to coronary bypass, 22 patients also received an automatic implantable cardioverter defibrillator (ICD), 26 patients received prophylactic ICD patches, and 1 patient had resection of a false aneurysm. There were no perioperative deaths. Postoperative electrophysiological studies were performed in all 56 surgical survivors. Ventricular tachyarrhythmia could not be induced in the six patients who had no inducible VT preoperatively and in 13 of 40 (33%) with preoperatively inducible sustained VT or in 19 of 50 (38%) patients with any previously inducible ventricular arrhythmia, thus a total of 25 patients (45%) had no inducible VT postoperatively. Of the remaining, 11 patients were treated with antiarrhythmic drugs alone, 11 had already received an ICD (combined with drugs in 7), and another 9 received the ICD postoperatively (combined with drugs in 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Strategies in the surgical treatment of malignant ventricular arrhythmias. An 8-year experience

Introduction of the automatic implantable cardioverter defibrillator (AICD) has dramatically affected the surgical treatment of malignant ventricular tachyarrhythmias. The authors continue to perform electrophysiologically directed subendocardial resection (SER) of left ventricular (LV) scars in selected patients, and we revascularize (CABG) those patients undergoing AICD implantation who have significant myocardial ischemia. In an attempt to define the optimal role of each procedure, this report analyzes our 8-year experience with 348 consecutive patients treated surgically for these arrhythmias (SER since 1983 and AICD since 1986). All patients undergoing SER had organized ventricular tachycardia (VT) as a result of myocardial infarction, and most had LV aneurysms; of those undergoing AICD or AICD/CABG, 60% had VT, 15% had ventricular fibrillation, and 25% had both or were noninducible. The thirty-day mortality rate was 1.5% (3/197) for AICD, 5.4% (5/93) for AICD/CABG, and 8.6% (5/58) for SER; these mortality figures are not significant different. Late deaths in all groups were predominantly due to congestive heart failure, and actuarial survival as well as freedom from sudden death was similar between the groups at 4 years. Recurrent VT occurred in 167 of 282 (59%) of long-term survivors of AICD or AICD/CABG during follow-up and in nine of 53 (17%) of those with SER. Forty-eight per cent of survivors of AICD or AICD/CABG required antiarrhythmic medications, whereas only 11% of those with SER required antiarrhythmics. Long-term survival in each group is much higher than that reported for comparable patients with severe LV dysfunction treated medically. In those patients with organized VT and LV aneurysm who are judged able to survive the procedure, SER offers a high likelihood of cure rather than simple prevention of sudden death.

Retrospective analysis of patients undergoing one- or two-stage strategies for myocardial revascularization and implantable cardioverter defibrillator implantation

Internal defibrillation leads were placed at time of coronary revascularization in 79 patients. In 34, an implantable cardioverter defibrillator (ICD) was placed simultaneously (group I). A two-stage strategy (selective implantation of the ICD in patients with postoperative spontaneous or inducible ventricular tachycardia [VT]) was followed in 45 patients (group II). Group I patients had failed more antiarrhythmic drug trials (2.9 +/- 1.6 vs 1.5 +/- 1.6; P = 0.02), including amiodarone (62% vs 20%; P less than 0.001). There were four operative deaths in each group. Postoperatively, VT was present in 27 group II patients (60%), 25 of whom received an ICD (two refused device implantation). Patients with postoperative VT had a lower left ventricular ejection fraction than those without VT (33 +/- 9 vs 47 +/- 16; P = 0.01). Actuarial survival at 1, 2, and 3 years was 88 +/- 6, 88 +/- 7, and 88 +/- 10 in group I; and 83 +/- 6, 76 +/- 7, and 76 +/- 11 in group II (NS). No patient without an ICD (based on the postoperative electrophysiological study [EPS]) died suddenly. Five patients (6%) had ICD system infection. Sudden death was largely prevented by either strategy, but relatively high rates of operative mortality and ICD system infection were observed. Prospective studies should identify patients more likely to benefit from one or another strategy.

Significance of ventricular tachyarrhythmias complicating cardiac catheterization: a CASS Registry Study

Ventricular tachycardia and ventricular fibrillation are recognized complications of cardiac catheterization. Despite numerous reports documenting the frequency of these occurrences, their significance has not been systematically examined. Accordingly, the outcome of 108 patients who experienced either ventricular tachycardia or ventricular fibrillation during coronary angiography between 1975 and 1979 in the Coronary Artery Surgery Study (CASS) Registry were examined. There were 20,142 patients analyzed. Patients with ventricular tachyarrhythmias had more objective evidence of left ventricular impairment, clinical heart failure, and ventricular arrhythmia recorded as a clinical symptom. The overall 5-year survival rates were 83% and 88% for patients with and without ventricular tachyarrhythmias, respectively (p = 0.07). When ventricular function, age, gender, angina, and previous myocardial infarction were added in a stepwise Cox survival analysis, the presence of arrhythmias was not significant (p = 0.66). At 5 years, 80% of the medically treated patients and 82% of the surgically treated patients remained alive (p = 0.95). The only statistically significant differences in the patients with ventricular arrhythmias who were treated medically or surgically were age (medically treated patients 52 +/- 10 years, surgical patients 57 +/- 9 years, p = 0.01) and number of diseased vessels (p less than 0.001). In a stepwise Cox survival analysis, functional impairment secondary to congestive heart failure was the only significant covariate to affect survival in the medical and surgical groups (p = 0.0001). Surgical therapy itself was not significant (p = 1.00). The incidence of sudden death during 5 years for patients with and without ventricular tachyarrhythmias during catheterization was 5% and 4%, respectively (p = 0.28).(ABSTRACT TRUNCATED AT 250 WORDS)

Medical costs of coronary artery disease in the United States

A model has been developed to determine the cost of coronary artery disease (CAD) based on the 5 primary events identified in the Framingham Study: acute myocardial infarction, angina pectoris, unstable angina pectoris, sudden death and nonsudden death. The costs for diagnostic and therapeutic service for patients with CAD were linked to medical decision algorithms outlining the diagnosis and management of patients with CAD. Because CAD is a changing illness not represented by a single event, the algorithm tracked patients for 5 years after the time of diagnosis, or until death, to develop average cost estimates. The estimated 5-year costs (in 1986 United States dollars) of the 5 CAD events were: acute myocardial infarction $51,211, angina pectoris $24,980, unstable angina pectoris $40,581, sudden death $9,078 and nonsudden death $19,697. The costs of major CAD surgical procedures were also calculated because of their impact on health care costs for patients with CAD. These include: coronary artery bypass surgery per case over 5 years $32,465, and angioplasty per case over 5 years $26,916. The high cost of CAD reflects the improved technology and more effective and expensive therapies now available.

Evolving patterns in the surgical treatment of malignant ventricular tachyarrhythmias

The advent of the automatic implantable cardioverter defibrillator (AICD), generally viewed as a safe and effective intervention, has in some measure discouraged the use of electrophysiologically directed endocardial resection for intractable ventricular arrhythmias. We reviewed the records of 127 patients undergoing either AICD procedures or resection over a 6-year period. Thirty-day mortality was 5.6% (5/89 patients) for all AICD procedures, 10.7% (3/28) for AICD placement plus coronary artery bypass grafting, and 11.8% (4/34) for resection. These mortality figures are not significantly different. Patients undergoing resection were less likely to require antiarrhythmic agents than patients given an AICD (33% versus 61%). Survival at 2 years was 78% in the resection group and 72% in the AICD group. Survival at 4 years was still 78% in the resection group. Only 1 late sudden death occurred in the AICD group and none in the resection group. We conclude that resection continues to be a valuable alternative, offering a greater overall benefit at only slightly increased risk.

Sudden cardiac death

Most sudden deaths in industrial nations are the result of underlying coronary artery disease. Longitudinal studies have demonstrated that the percent of all coronary events presenting as sudden death increases with age in both men and women. Relative weight is another important risk factor; the age-adjusted rate of sudden cardiac death for the upper weight tercile in the Framingham study was over 2 times higher for men and 3 times higher for women than the rate for the lower weight tercile. Most patients who die suddenly initially experience ventricular tachycardia that subsequently degenerates into ventricular fibrillation. Patients with a high risk of sudden cardiac death include: survivors of myocardial infarction with left ventricular dysfunction or complex ventricular ectopy, or both; survivors of out-of-hospital cardiac arrest, particularly when the event is not associated with an acute myocardial infarction; patients with recurrent ventricular tachycardia; and patients with dilated congestive cardiomyopathy, particularly when associated with ventricular ectopy. Reducing the risk of sudden death in these patients remains a major challenge.

Impending sudden cardiac death: treatment with myocardial revascularization and the automatic implantable cardioverter defibrillator

Myocardial revascularization and implantation of the automatic implantable cardioverter defibrillator (AICD) have individually been shown to improve survival in patients after sudden cardiac death. Their combined role has not been well defined. Twenty-three survivors of sudden death underwent revascularization and AICD implantation at an average age of 59 years. The initial arrest was caused by ventricular fibrillation in 15 and ventricular tachycardia in 8. Exercise stress tests, ambulatory ECGs, and electrophysiological monitoring with programmed electrical stimulation were done preoperatively and postoperatively. Follow-up averaged 24 months with a two-year survival of 91%. Eight patients (35%) required AICD resuscitation an average of 8 months postoperatively, and electrophysiological testing did not accurately predict arrhythmia recurrence. The addition of AICD implantation to revascularization substantially improves survival of patients with sudden cardiac death.

Electrophysiologic study in the management of cardiac arrest survivors: a critical review

This review discusses the value and limitations of EPS in the management of cardiac arrest survivors. Uncertainties associated with EPS include a lack of consensus with respect to stimulation protocol, end points for VT suppression during drug testing, significance of induced polymorphic VT or VF, and timing of EPS after myocardial infarction. Despite methodologic shortcomings in most clinical studies, a useful body of knowledge has emerged. In cardiac arrest survivors, incidence of inducible sustained VT ranged from 35% to 75%. Where induced VT (sustained or nonsustained) was successfully suppressed, recurrent arrhythmic events occurred in 0% to 33% of patients over a 1- to 5-year follow-up period. Failed regimens correlated with a high risk of arrhythmic recurrence. EPS also helps to select patients for the implantable defibrillator or electrocardiac surgery. In conclusion, EPS appears empirically useful in the management of cardiac arrest survivors with coronary artery disease; its value in other disease entities is uncertain.

Role of myocardial ischemia during programmed stimulation in survivors of cardiac arrest with coronary artery disease

The role of ischemia in the induction of ventricular tachycardia during programmed stimulation was studied in 19 patients who survived a cardiac arrest and were found to have a significant stenosis in at least one branch of the left coronary artery. The arterial-coronary sinus lactate difference was measured during electrophysiologic testing, before the induction of ventricular tachycardia. Ventricular tachycardia was induced in 15 patients; it was sustained and unimorphic in 6 patients and polymorphic in 9. Myocardial ischemia, as reflected by net myocardial lactate production, was present within 60 seconds before the induction of ventricular tachycardia in 8 of the 15 patients with inducible ventricular tachycardia. In 9 of the 15 patients, programmed stimulation was repeated after a 15 minute rest period, with the same coupling intervals that had induced ventricular tachycardia previously. Net myocardial lactate production was not present in any patient during this repeat attempt. In three patients without evidence of ischemia during the first induction of ventricular tachycardia, the arrhythmia was induced again by the specific coupling intervals that had induced it previously. However, in five of six patients with net myocardial lactate production during the first induction of ventricular tachycardia, the same coupling intervals that had induced the arrhythmia in the presence of ischemia no longer induced it in the absence of ischemia. The results of this study suggest that myocardial ischemia may be a requirement for the induction of ventricular tachycardia in some patients with coronary artery disease who survive a cardiac arrest.