Effect of ventricular fibrillation complicating acute myocardial infarction on long-term prognosis: importance of the site of infarction

Optogenetic modulation of cardiac autonomic nervous system

The following is a narrative review of the fundamentals of optogenetics. It focuses on the advantages and constraints of manipulating the autonomic nervous system by modifying the pathophysiological characteristics that arise in different diseases. Although the use of this technique is currently experimental, we will discuss improvements that have been implemented and identify the necessary measures for potential preclinical translation in the control of the cardiac autonomic nervous system.

Autonomic Modulation of Cardiac Arrhythmias: Methods to Assess Treatment and Outcomes

The autonomic nervous system plays a central role in the pathogenesis of multiple cardiac arrhythmias, including atrial fibrillation and ventricular tachycardia. As such, autonomic modulation represents an attractive therapeutic approach in these conditions. Notably, autonomic modulation exploits the plasticity of the neural tissue to induce neural remodeling and thus obtain therapeutic benefit. Different forms of autonomic modulation include vagus nerve stimulation, tragus stimulation, renal denervation, baroreceptor activation therapy, and cardiac sympathetic denervation. This review seeks to highlight these autonomic modulation therapeutic modalities, which have shown promise in early preclinical and clinical trials and represent exciting alternatives to standard arrhythmia treatment. We also present an overview of the various methods used to assess autonomic tone, including heart rate variability, skin sympathetic nerve activity, and alternans, which can be used as surrogate markers and predictors of the treatment effect. Although the use of autonomic modulation to treat cardiac arrhythmias is supported by strong preclinical data and preliminary studies in humans, in light of the disappointing results of a number of recent randomized clinical trials of autonomic modulation therapies in heart failure, the need for optimization of the stimulation parameters and rigorous patient selection based on appropriate biomarkers cannot be overemphasized.

Prognostic impact of early ventricular fibrillation in patients with ST-elevation myocardial infarction treated with primary PCI

AIMS

Current guidelines do not advocate implantation of cardioverter-defibrillators (ICD) for survivors of ventricular fibrillation (VF) during the first 48 hours of ST-elevation myocardial infarction (STEMI). However, contemporary studies in a real-life setting with long-term follow-up are lacking. We assessed the prognostic impact of early VF in a non-selected population of STEMI patients treated with primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Consecutive STEMI patients admitted to a Swedish tertiary care hospital during 2007-2009 were identified from the Register of Information and Knowledge about Swedish Heart Intensive Care Admissions (n=1718, age 66±12 years, 70% male). Patients with VF were identified from the register, and medical records were reviewed to determine the time point of VF. Patients surviving VF in the first 48 hours after symptom onset were compared with patients without VF for one-year mortality and a combined endpoint of death, resuscitated VF or appropriate ICD therapy. VF within 48 hours occurred in 7% of STEMI patients (n=121). In patients alive at 48 hours (n=1663), VF patients (n=101) had higher in-hospital mortality (12% vs. 2%, p<0.001). However, in VF patients discharged alive (n=89), mortality was low (1%) and combined endpoint rate (3%) did not differ compared with patients without VF (n=1538; 4% and 4% respectively).

CONCLUSION

In a large non-selected population of STEMI patients treated with primary PCI, VF during the first 48 hours after STEMI is associated with increased in-hospital mortality but does not influence the long-term prognosis for those discharged alive.

Sudden death

Sudden death is probably the greatest challenge in modern cardiology. After reviewing its history, we describe the epidemiology of sudden death and its associated diseases. We highlight its physiopathologic aspects, including the factors that act on vulnerable myocardium triggering the final arrhythmia, mainly ventricular fibrillation and, to a lesser extent, bradycardia and sudden death. We emphasize the relevance of acute ischemia, ventricular dysfunction and genetic factors, not only in genetic heart disease, but also as triggers of sudden death in acute and chronic ischemic heart disease. Finally, we describe the best way to identify candidates at risk, discuss how to prevent sudden death, and outline the best approach to managing a patient resuscitated from cardiac arrest. Full English text available from:www.revespcardiol.org.

Familial Sudden Death Is an Important Risk Factor for Primary Ventricular Fibrillation

BACKGROUND

Primary ventricular fibrillation (VF) accounts for the majority of deaths during the acute phase of myocardial infarction. Identification of patients at risk for primary VF remains very poor.

METHODS AND RESULTS

We performed a case-control study in patients with a first ST-elevation myocardial infarction (STEMI) to identify independent risk factors for primary VF. A total of 330 primary VF survivors (cases) and 372 controls were included; patients with earlier infarcts or signs of structural heart disease were excluded. Baseline characteristics, including age, gender, drug use, and ECG parameters registered well before the index infarction, as well as medical history, were not different. Infarct size and location, culprit coronary artery, and presence of multivessel disease were similar between groups. Analysis of ECGs performed at hospital admission for the index STEMI revealed that cumulative ST deviation was significantly higher among cases (OR per 10-mm ST deviation 1.59, 95% CI 1.25 to 2.02). Analysis of medical histories among parents and siblings showed that the prevalence of cardiovascular disease was similar between cases and controls (73.1% and 73.0%, respectively); however, familial sudden death occurred significantly more frequently among cases than controls (43.1% and 25.1%, respectively; OR 2.72, 95% CI 1.84 to 4.03).

CONCLUSIONS

In a population of STEMI patients, the risk of primary VF is determined by cumulative ST deviation and family history of sudden death.

Resuscitation from out-of-hospital cardiac arrest: implications for cardiac enzyme estimation

BACKGROUND

diagnosis of precipitating myocardial infarction is essential for management of victims of out-of-hospital cardiac arrest, since investigations and treatment are determined by the underlying cause. Skeletal muscle and myocardial damage from external cardiac massage and defibrillation may complicate biochemical diagnosis of myocardial infarction.

OBJECTIVES

(a) to examine the relationship between cumulative defibrillation energy and serum levels of cardiac troponin T and MB creatine kinase (MB-CK) mass in out-of-hospital cardiac arrest survivors without electrocardiographic evidence of myocardial infarction; (b) to reassess diagnostic thresholds for myocardial infarction using MB-CK mass and troponin T in this setting.

METHODS

77 victims of out-of-hospital cardiac arrest were studied. Serum was obtained for MB-CK mass, CK and troponin T estimation on the first 4 days of admission. Patients were divided into three groups using electrocardiographic criteria: group 1, myocardial infarction; group 2, no evidence of infarction; and group 3, equivocal electrocardiograms. Correlation coefficients were calculated for highest recorded levels of the biochemical markers versus defibrillation energy. Receiver-operating characteristic plots were used to determine optimum biochemical diagnostic thresholds for subjects in groups 1 and 2.

RESULTS

using predefined criteria, 27 patients had myocardial infarction, 34 did not have myocardial infarction and 16 had equivocal electrocardiograms. Significant correlations were found for defibrillation energy versus log troponin T (r = 0.42, P < 0.05), log MB-CK mass (r = 0.51, P < 0.01) and total CK (r = 0.68, P < 0.001) in group 2. Within groups 1 and 2, MB-CK mass and troponin T provided additional diagnostic value over MB-CK fraction (P < 0.001). Diagnostic accuracy was not improved by adjusting for shock energy. The optimum threshold value was 4 ng/ml for troponin T (sensitivity 88%, specificity 95%), 60 ng/ml for MB-CK mass (sensitivity 88%, specificity 88%) and 8% of total CK for MB-CK fraction (sensitivity 74%, specificity 82%). These values should be interpreted with caution, since this study is limited by the exclusion of patients with uncertain electrocardiographic diagnoses into group 3.

CONCLUSIONS

skeletal muscle and myocardial damage occurs in survivors of out-of-hospital cardiac arrest and is related to the duration of resuscitation. This complicates biochemical diagnosis of underlying myocardial infarction. Specific high diagnostic threshold values for MB-CK and troponin T are needed to optimise diagnostic accuracy. The use of MB-CK fraction leads to greater diagnostic error because of the variability of muscle CK release after resuscitation.

Incidence and prognosis of secondary ventricular fibrillation in acute myocardial infarction. Evidence for a protective effect of thrombolytic therapy. GISSI Investigators

The multicenter randomized study of the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico has provided the opportunity to analyze the impact of thrombolytic treatment on secondary ventricular fibrillation incidence in a large population of patients (11,712) with acute myocardial infarction. A reduction of about 20% in the frequency of secondary ventricular fibrillation was observed among patients allocated to thrombolytic treatment (streptokinase, 2.4% versus control, 2.9%; relative risk, 0.80; 95% confidence interval, 0.64-1.00). Streptokinase appeared to exert its protective effect specifically in patients treated within 3 hours of onset of symptoms (streptokinase, 2.6% versus control, 3.7%; relative risk, 0.71; 95% confidence interval, 0.53-0.95). This protection was essentially due to a reduced incidence of late ventricular fibrillation occurring after the first day of hospitalization. The 311 patients with secondary ventricular fibrillation represented an overall incidence of 2.7%. Such incidence was not related to infarct location or sex but was significantly more common in patients older than 65 years (3.3% versus 2.3% in younger patients). A significant excess of in-hospital deaths was found in patients with secondary ventricular fibrillation compared with those in the reference group (38% versus 24%; relative risk, 1.98; 95% confidence interval, 1.56-2.52). Conversely, secondary ventricular fibrillation was not a predictor of 1-year mortality for hospital survivors. Thrombolytic treatment with intravenous streptokinase affords protection against secondary ventricular fibrillation most probably by a limitation of infarct size. When the arrhythmia complicates the course of infarction, it is associated with an adverse short-term outcome, whereas the long-term prognosis is not influenced.

Determinants of prognosis in symptomatic ventricular tachycardia or ventricular fibrillation late after myocardial infarction. The Dutch Ventricular Tachycardia Study Group of the Interuniversity Cardiology Institute of The Netherlands

In a multicenter study, 390 patients with sustained symptomatic ventricular tachycardia or ventricular fibrillation late after acute myocardial infarction were prospectively followed up to assess determinants of mortality and recurrence of arrhythmic events. Patients were given standard antiarrhythmic treatment, which consisted primarily of drug therapy. During a mean follow-up period of 1.9 years, 133 patients (34%) died; arrhythmic events and heart failure were the most common cause of death (41 patients [11%] died suddenly, 31 [8%] died because of recurrent ventricular tachycardia or ventricular fibrillation and 23 [6%] died of heart failure). One hundred ninety-two patients (49%) had at least one recurrent arrhythmic event; 85% of first recurrent arrhythmic events were nonfatal. Multivariate analysis of data from patients who developed the arrhythmia less than 6 weeks after infarction identified five variables as independent determinants of total mortality: 1) age greater than 70 years (risk ratio 4.5); 2) Killip class III or IV in the subacute phase of infarction (risk ratio 3.5); 3) cardiac arrest during the index arrhythmia (risk ratio 1.7); 4) anterior infarction (risk ratio 2.2); and 5) multiple previous infarctions (risk ratio 1.6). Multivariate analysis of data from patients developing the arrhythmia greater than 6 weeks after infarction identified four variables as independently predictive of total mortality: 1) Q wave infarction (risk ratio 2.1); 2) cardiac arrest during the index arrhythmia (risk ratio 1.7); 3) Killip class III or IV in the subacute phase of infarction (risk ratio 1.7); and 4) multiple previous infarctions (risk ratio 1.4). The results of the two multivariate analyses were used in a model for prediction of mortality at 1 year. The average predicted mortality rate varied considerably according to the model: for 243 patients (62%) with the lowest risk, it was 13%, corresponding to an observed mortality rate of 12%; for 92 patients (24%) with intermediate risk, it was 27%, corresponding to an observed rate of 28%; for 55 patients (14%) with the highest risk, it was 64%, corresponding to an observed rate of 54%. This study shows that patients with symptomatic ventricular tachycardia or ventricular fibrillation late after myocardial infarction who are given standard antiarrhythmic treatment have a high mortality rate. The predictive model presented identifies patients at low, intermediate and high risk of death and can be of help in designing the appropriate diagnostic and therapeutic strategy for the individual patient.

Clinical implications of new studies in the treatment of benign, potentially malignant and malignant ventricular arrhythmias

For purposes of clinical management, ventricular arrhythmias have been divided into risk categories of benign, prognostically important (potentially malignant) and malignant. Benign arrhythmias occur in the setting of structurally normal hearts and do not require therapy unless associated with debilitating symptoms. Malignant arrhythmias such as sustained ventricular tachycardia or fibrillation deserve aggressive therapy to prevent recurrence. Arrhythmias occurring in the presence of organic heart disease (often ischemic disease) are frequently asymptomatic but prognostically important as a risk factor for sudden death or cardiac arrest. The common empiric practice to treat such arrhythmias (by about 40 to 50% of cardiologists in the United States) needs to be reassessed in the face of the Cardiac Arrhythmia Suppression Trial. For malignant arrhythmias, class IA agents (procainamide and quinidine) continue to be the standard of treatment, and class IB agents (e.g., mexiletine) may be used as alternative or additive therapy. Class IC agents are used as second-line therapy, especially in the setting of ischemic heart disease. Class III therapy with amiodarone is reserved for refractory patients because of potential toxicity. Sotalol, a new class II-III agent, may become a first-line drug. For prognostically important arrhythmias, beta blockers remain the agents of choice, class IC agents are contraindicated, and class IA or IB drugs, or both, should be used conservatively (i.e., only for symptomatic arrhythmias). For symptomatic but benign arrhythmias requiring treatment, beta blockers are safe although not always effective. Class IA, IB and IC agents may then be considered. In these patients, the proarrhythmic potential of quinidine and class IC agents remains a concern.(ABSTRACT TRUNCATED AT 250 WORDS)

One-year prognosis of primary ventricular fibrillation complicating acute myocardial infarction. The GISSI (Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto miocardico) investigators

The 1-year prognosis of 293 patients discharged alive from the hospital after acute myocardial infarction (AMI), who experienced primary ventricular fibrillation (VF) in the acute phase, was compared with that of a reference group of 6,337 patients identified from the same population included in the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto miocardico (GISSI) trial. There was no difference in the 6- and 12-month mortality between the patients with primary VF and the reference group (3.7 vs 2.7% and 4.1 vs 4.2%, respectively). Survival of the 2 groups was also similar when patients were stratified according to infarct site (anterior and posterior), and whether or not they received treatment with streptokinase during AMI. Thus, long-term mortality of patients discharged alive after AMI complicated by primary VF is low and is not influenced by previous fibrinolytic therapy or by infarct site. The excess mortality of patients with primary VF is confined to the hospital phase, after which survivors represent a low-risk subgroup.

Long-term prognosis after resuscitation from primary ventricular fibrillation complicating acute transmural myocardial infarction in the north east of Scotland

The aim of this study is to determine the long-term prognosis of patients successfully resuscitated from primary ventricular fibrillation in the acute phase of transmural myocardial infarction and to identify predictors of mortality. Details of 75 consecutive patients between October 1971 and May 1981 were reviewed in October 1985. The cumulative survival rates at one year, two year, five year and 10 year were 84%, 77% 67% and 40.5% respectively with a median survival time of 8.7 years. Univariate and Cox survival analyses were used to determine predictors of mortality. Only the age of the patient at the time of infarction was found to be highly significant with a greatly increased mortality rate in the older age group (p less than 0.001). The sex, site of infarction (anterior or inferior) and time of entry in the study did not significantly influence long-term prognosis.

Arrhythmia prophylaxis after acute myocardial infarction: a decade of controversy

Primary ventricular fibrillation continues to be a major complication of acute myocardial infarction occurring in 5-9% of patients in the coronary care unit and in a higher percentage of pre-hospital admissions. Prophylactic anti-arrhythmic drugs can prevent primary ventricular fibrillation. Lidocaine has been used for this purpose and can be administered safely and effectively in most patients by following well-established programs based on pharmacokinetic and pharmacodynamic data. The in-hospital mortality for patients with primary ventricular fibrillation exceeds that of matched controls not having the arrhythmia, and many studies show a higher 1-, 3-, and 5-year mortality. Other studies have failed to confirm these long-term results and have produced controversy among cardiologists. I continue to recommend prophylactic antiarrhythmic drugs for all patients with acute infarction, especially in those undergoing early interventional therapy.

Identification of persons at risk for sudden cardiac death

Before any more progress is made in reducing the incidence of sudden cardiac death, our ability to identify those at risk must be refined further. The close association with coronary artery disease necessitates that the first step must be the identification of those with underlying coronary artery disease. This is underscored by the disturbing fact that, in many, sudden death is the first sign of coronary disease. An aggressive evaluation of those with significant risk factors appears justified. The second part of the problem is the identification of those with coronary artery disease who are at especially high risk. The current diagnostic modalities available suffer from a relative lack of specificity to be applied indiscriminately in light of the expense and morbidity of effective therapies (that is, coronary artery bypass surgery, antiarrhythmic drugs, implantable defibrillators, surgical or catheter ablation). At the present time, we can identify certain subsets that warrant aggressive therapy: survivors of sudden death events or sustained ventricular tachycardia, obstructive cardiomyopathies, aortic stenosis, left main coronary artery disease, and congenital QT prolongation. Less aggressive but also less specific therapies, such as beta-blockers in myocardial infarction survivors, can be given more indiscriminately. Ultimately, of course, the greatest impact will come from prevention of coronary artery disease.

Baroreflex sensitivity and its evolution during the first year after myocardial infarction

Experimental data have indicated that baroreflex sensitivity is often depressed in dogs after myocardial infarction and that this depression correlates strongly with subsequent mortality during episodes of acute myocardial ischemia. This finding has several clinical implications. The present study was undertaken with the objectives of assessing the potential existence of differences in baroreflex sensitivity between men with and without myocardial infarction and the time course during the 1st year after infarction of these potential changes in baroreflex sensitivity. Fifty-three subjects entered the study: 32 postinfarction patients and 21 control subjects. Baroreflex sensitivity was assessed by increasing mean blood pressure by aphenylephrine infusion (70 micrograms/ml) and recording the consequent RR interval changes. Baroreflex sensitivity, expressed as the slope of the regression line relating mean blood pressure to RR interval changes, was evaluated 18 days (n = 32), 3 months (n = 17) and 13 months (n = 10) after infarction. Baroreflex sensitivity was lower in the patients than in the control subjects (8.2 +/- 3.7 versus 12.3 +/- 2.9 ms/mm Hg, p = 0.0001). Moreover, 13 (41%) of 32 patients had a baroreflex slope less than 6.5 ms/mm Hg, which was 2 SD below the mean value of the control subjects. The internal control follow-up study showed that baroreflex sensitivity increased 3 months after infarction to values quite similar to those observed in the control subjects (11.1 +/- 5.3 versus 8.7 +/- 3.5 ms/mm Hg, p = 0.02). No further change was observed between 3 and 13 months after myocardial infarction. These data indicate that baroreflex sensitivity is lower in a proportion of postinfarction patients than in control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Late clinical outcome in patients with early ventricular fibrillation after myocardial infarction

Whether ventricular fibrillation occurring within 48 h after acute myocardial infarction is associated with particular clinical features and poor prognosis, especially in patients with anterior myocardial infarction, is still debated. Therefore, clinical variables and in-hospital and 1 year mortality rates were analyzed in 2,088 patients, aged 18 to 95 years (mean +/- SD 64 +/- 12), admitted to the hospital with acute myocardial infarction between 1979 and mid 1984. One hundred forty-seven patients (7%) had at least one episode of ventricular fibrillation occurring within 48 h of hospital admission. Of these, 25% died during their initial hospitalization compared with 13% of patients without early ventricular fibrillation (p less than 0.001). In greater than 50% of patients with early ventricular fibrillation, the immediate cause of death was left ventricular failure or cardiogenic shock. In contrast, the 1 year mortality rate after hospital discharge was not significantly greater in patients with than in those without early ventricular fibrillation (15 versus 11%, respectively), particularly in the subgroup of patients with anterior myocardial infarction in which the mortality rate tended to be lower in patients with early ventricular fibrillation (8 versus 14%, respectively). Similar mortality results were found when only primary (not associated with left ventricular failure) ventricular fibrillation was analyzed. The left ventricular ejection fraction and the incidence of complex ventricular arrhythmias from 24 h ambulatory electrocardiographic monitoring obtained at hospital discharge were not different in survivors with or without early ventricular fibrillation (0.45 +/- 0.13 versus 0.49 +/- 0.14 and 41 versus 41%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognosis after cardiac arrest due to ventricular tachycardia or ventricular fibrillation associated with acute myocardial infarction (the MILIS Study). Multicenter Investigation of the Limitation of Infarct Size

Previous studies have reached conflicting conclusions about whether cardiac arrest due to ventricular tachycardia (VT) or ventricular fibrillation (VF) in acute myocardial infarction (AMI) is of long-term prognostic significance. The mortality rate in 849 patients with confirmed AMI was analyzed. The mortality rate during the initial hospitalization was higher for patients in whom VT/VF occurred (27% vs 7%, p less than 0.001). The in-hospital mortality rate for patients with primary VT/VF, that is, VT/VF occurring in the absence of hypotension or heart failure, was similar to that of patients who did not have VT/VF (8% vs 7%, difference not significant), whereas the rate for patients with secondary VT/VF was significantly greater than that for patients with no VT/VF (51% vs 7%, p less than 0.001). The timing of occurrence of VT/VF also influenced mortality: Patients in whom VT/VF occurred more than 72 hours after admission had a higher in-hospital mortality rate than did patients in whom it occurred within 72 hours (57% vs 20%, p less than 0.05). All cases of primary VT/VF occurred within the first 72 hours of admission. The long-term mortality rate for hospital survivors was not significantly different for patients who had had VT/VF during acute infarction compared with those who had not (19% vs 21%) (mean follow-up 32 months). Thus, cardiac arrest due to ventricular tachyarrhythmia was associated with a higher in-hospital mortality rate but was not a prognostic factor among hospital survivors. Patients resuscitated from primary VT/VF, which characteristically occurs early after AMI, do not have an adverse prognosis.

Arrhythmias as predictors of sudden death

Two methods are available for exploring arrhythmias in cardiac patients who are at risk of sudden death: Holter monitoring and invasive electrophysiology. Despite numerous studies, the predictive value of these techniques, in terms of prognosis, remains poor for many reasons. Neither technique considered individually can give reliable prognostic indications simply because each technique addresses different issues which are only partially involved in the mechanism of sudden death. Invasive electrophysiology, by artificially provoking an arrhythmia, detects the potential substrate which may ultimately lead to lethal arrhythmias. Although this is an important technique it is insufficient because merely identifying the substrate for an arrhythmia does not necessarily mean that arrhythmia will occur. On the other hand, ambulatory ECG allows monitoring of spontaneous arrhythmias which may be considered as potential initiating factors in arrhythmias. However, even if initiating factors and potential substrates are present, they are not sufficient conditions to cause lethal arrhythmias to occur. When there is an opportunity to scrutinize the mechanism of arrhythmias which are indeed lethal, as in sudden death, it appears that the lethal event results from the intervention of a new factor which was either absent or not considered during preceding investigations. In coronary patients, curiously, ischemia more often provokes cardiac arrest or an electromechanical dissociation rather than a ventricular tachycardia or fibrillation. Sudden death is not infrequently of iatrogenic origin, because of the arrhythmogenic effect of powerful antiarrhythmic drugs. More important, ventricular fibrillation often occurs in the setting of a progressively increased sympathetic tone, which explains either the particular seriousness of a previously known arrhythmia or the occurrence of an arrhythmia which was never before observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Outcome of primary coronary recanalization and arrhythmia profile in survivors of acute myocardial infarction

The purpose of this study was to assess the arrhythmia profile in survivors of acute myocardial infarction in whom recanalization of the infarct-related vessel was attempted. 127 patients with acute myocardial infarction were randomized to intravenous and intracoronary thrombolysis with or without transluminal coronary angioplasty. 84 of them, aged 54 +/- 9 years, had angiographic control, 24-hour Holter electrocardiographic monitoring and programmed electrical stimulation 4 weeks after infarction. The study protocol of programmed electrical stimulation included single and double extrastimuli at 2 driving cycle lengths. The end point was the induction of ventricular tachycardia with 10 and more beats. During infarction 28 patients had occlusion of the left anterior descending, 12 of the circumflex and 44 of the right coronary artery. Holter monitoring revealed both frequent (greater than 100 ventricular premature complexes per 24 hours) and repetitive (Lown IVA, IVB) ventricular arrhythmias in 23 patients (27%). Inducible ventricular tachycardia (greater than 6 beats) was found in 25 patients (30%), which was sustained in 4 patients. According to the angiographic results two groups of patients could be identified: group A consisted of 64 patients who showed primary recanalization of the infarct-related vessel with persistent patency at control. Group B consisted of 20 patients who showed late reopening (n = 5) or a closed infarct-related vessel (n = 15) due to late reocclusion in 9 of them. Frequent ventricular premature contractions occurred in 18 group A and in 5 group B patients (n.s.). Repetitive ventricular premature contractions were found in 21 group A and in 2 group B patients (P less than 0.05). Inducible ventricular tachycardia was observed in 17 patients of group A (27%) and in 8 patients of group B (40%) (n.s.). The incidence of spontaneous and stimulus-induced ventricular arrhythmias was not influenced by the type of recanalization procedure. Furthermore no relation to the time interval between onset of preinfarct angina and angiographically demonstrated reperfusion of the infarct-related vessel was found. The patients in the two groups did not differ with respect to left ventricular ejection fraction, number of abnormal contracting wall segments or site of infarction. It is concluded that reperfusion infarction does not differ from infarction due to permanent occlusion with respect to inducible ventricular tachycardia but may favor repetitive ectopic activity.