Comparison of programmed stimulation and Holter monitoring for predicting long-term efficacy and inefficacy of amiodarone used alone or in combination with a class 1A antiarrhythmic agent in patients with ventricular tachyarrhythmia

The values of two Holter ambulatory electrocardiographic monitoring criteria and one programmed stimulation efficacy criterion reported to be predictive of the efficacy of amiodarone were compared in 70 patients taking amiodarone for sustained ventricular tachyarrhythmias. At baseline, all patients had ventricular tachycardia inducible by programmed stimulation. After amiodarone loading (935 +/- 271 mg for 16 +/- 7 days), efficacy was determined by a programmed stimulation criterion (ventricular tachycardia no longer inducible or less than or equal to 15 beats) and two Holter monitoring criteria (Holter I = greater than or equal to 85% reduction of ventricular premature complexes and abolition of couplets and triplets in 64 patients who had greater than or equal to 10 ventricular premature complexes/h or couplets or triplets or both before therapy; Holter II = abolition of triplets in 41 patients who had triplets before therapy). Amiodarone was effective in 12 of 70 patients by the programmed stimulation criterion, in 49 of 64 patients by Holter criterion I and in 37 of 41 patients by Holter criterion II. In assessing efficacy of amiodarone, programmed stimulation and Holter criteria were discordant in 69% of patients or more (p less than 0.001). There were 16 recurrences or sudden deaths during the entire follow-up period (19 +/- 19 months). Arrhythmia-free survival rates at 24 months of patients with efficacy and inefficacy by each criterion, respectively, were 90 and 78% by programmed stimulation, 84 and 62% by Holter criterion I (p less than 0.05) and 73 and 50% by Holter criterion II (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Discordance between ambulatory monitoring and programmed stimulation in assessing efficacy of mexiletine in patients with ventricular tachycardia

Programmed electrical stimulation (PES) and 24-hour Holter monitoring were compared in 30 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) before and during treatment with mexiletine. Before treatment, all patients had greater than or equal to 30 ventricular premature complexes (VPCs)/hr and 22 patients had nonsustained VT on Holter. All had inducible sustained VT by PES (one to three extrastimuli). Mexiletine was effective in only 23% by PES criteria (VT no longer inducible or less than or equal to 15 beats in duration and effective in 57%, 57%, and 73% by Holter criteria I, II, and III, respectively (Holter I greater than or equal to 50% reduction of VPCs, greater than or equal to 90% reduction of couplets and abolition of nonsustained VT; Holter II greater than or equal to 83% reduction of VPCs and abolition of VT; Holter III abolition of VT in patients who had VT during baseline Holter). Results of PES and Holter were discordant in 67%, 60%, and 55% (PES vs Holter I, II, and III, respectively). The majority (greater than or equal to 75%) of the discordance occurred due to mexiletine appearing effective by Holter criteria but ineffective by PES criteria (suggesting insensitivity of efficacy by Holter criteria and/or nonspecificity of induced VT during treatment with mexiletine). Conclusions: PES and Holter are discordant in assessing efficacy of mexiletine (p less than 0.05). Efficacy of mexiletine by Holter criteria is easier to achieve than efficacy by PES. The discordance between the two methods, both with very good reported predictive values, calls for randomized clinical follow-up studies to determine sensitivity and specificity of each method in assessing efficacy of mexiletine.     

Value of Holter monitoring in predicting long-term efficacy and inefficacy of amiodarone used alone and in combination with class 1A antiarrhythmic agents in patients with ventricular tachycardia

The value of two reported and two new ambulatory electrocardiographic (Holter) criteria was studied in 80 patients taking amiodarone for refractory recurrent sustained ventricular tachycardia. In the 80 patients, the four Holter criteria were as follows: I-85% or greater reduction of ventricular premature complexes and abolition of couplets and nonsustained ventricular tachycardia in 74 patients who had 10 or more ventricular premature complexes/h, or any couplets or nonsustained ventricular tachycardia/24 hours at baseline; II-abolition of nonsustained ventricular tachycardia in 51 patients who had nonsustained ventricular tachycardia at baseline; III-85% or greater reduction of ventricular premature complexes and abolition of nonsustained ventricular tachycardia in 64 patients who had 30 or more ventricular premature complexes/h at baseline; and IV-85% or greater reduction of ventricular premature complexes and abolition of nonsustained ventricular tachycardia in 73 patients who had 10 or more ventricular premature complexes/h at baseline. Amiodarone was judged effective in, respectively, 51 of 74, 44 of 51, 51 of 64 and 61 of 73 patients by criterion I, II, III or IV. During the follow-up period (19 +/- 20 months), there were 19 instances of recurrence of ventricular arrhythmia or sudden death. Actuarial arrhythmia-free survival rate at 24 months was 84, 74, 86 and 85%, respectively, in patients with efficacy by criterion I, II, III or IV and 61, 43, 48 and 39%, respectively, in patients with inefficacy (p less than 0.015 for all). Many patients with efficacy by Holter criteria, however, had a recurrence of arrhythmia, suggesting insensitivity of these Holter criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrophysiologic effects and clinical efficacy of mexiletine used alone or in combination with class IA agents for refractory recurrent ventricular tachycardias or ventricular fibrillation

The electrophysiologic effects and clinical efficacy of mexiletine used alone or in combination with class IA agents were studied in 35 patients with recurrent sustained ventricular tachycardia (VT) or ventricular fibrillation refractory to nonexperimental antiarrhythmic agents. At baseline before therapy, all patients had inducible VT by programmed stimulation (1 to 3 extrastimuli) and frequent (at least 30/hour) ventricular premature complexes (VPCs) during Holter monitoring. Mexiletine therapy was effective by programmed stimulation (VT no longer inducible or 15 or less beats) in 8 and ineffective in 27 patients. Twenty patients were discharged with mexiletine (14 of whom took an additional class IA agent). The discharge regimen was effective by programmed stimulation in 6 of these 20 patients. In 14 patients the discharge regimen was ineffective by programmed stimulation, but all patients had a marked reduction of ventricular ectopic activity (at least 83% reduction of VPCs and abolition of non sustained VT). During the follow-up period of 18 +/- 13 months (mean +/- standard deviation), 4 patients had recurrences (3 with an ineffective regimen by programmed stimulation and 1 with an effective regimen by programmed stimulation). Arrhythmia-free survival rates at 12 and 24 months were 86% and 77%, as determined by the Kaplan-Meier method, in patients with an ineffective regimen by programmed stimulation, and 80% and 80% in patients with an effective regimen by programmed stimulation (p = 0.979 by log rank test).(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic value of the changes in the mode of ventricular tachycardia induction during therapy with amiodarone or amiodarone and a class 1A antiarrhythmic agent

The prognostic value of 3 previously reported programmed stimulation efficacy criteria was studied in 70 patients taking amiodarone for sustained ventricular tachycardia (VT). At baseline all patients had VT inducible by programmed stimulation. After amiodarone loading (935 +/- 271 mg/day for 16 +/- 7 days), efficacy of amiodarone was determined by 3 programmed stimulation criteria (criterion I = VT not inducible or 15 beats or less; criterion II = VT not inducible or harder to induce; criterion III = VT not easier to induce). Amiodarone was effective in 12, 25 and 49 of 70 patients by criteria I, II and III, respectively. There were 16 recurrences or cardiac arrest during the follow-up period (19 +/- 19 months). Actuarial arrhythmia-free survival rates at 1 and 2 years were: 90% and 90% in patients with efficacy by criterion I and 78% and 78% in patients with inefficacy, respectively; 84% and 84% in patients with efficacy by criterion II and 78% and 78% in patients with inefficacy, respectively; and 80% and 80% in patients with efficacy by criterion III and 79% and 79% in patients with inefficacy, respectively (difference not significant for all). From the results of follow-up at 2 years, sensitivities of criteria I, II and III were 92%, 75% and 33%, respectively. Specificities were 17%, 26% and 70%, respectively, and predictive accuracies were 43%, 43% and 67%, respectively. Thus, patients with efficacy by criterion I appear to have a better prognosis when compared with patients with inefficacy. However, many patients with inefficacy by criterion I had a good outcome (nonspecificity).(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of silent ischemia, the arrhythmic substrate and the short-long sequence in the genesis of sudden cardiac death

To study the role of silent ischemia and the arrhythmic substrate in the genesis of sudden cardiac death, 67 patients were studied (mean age 62 +/- 12 years). Of these, 14 patients (Group 1) had an in-hospital episode of ventricular tachycardia or fibrillation while wearing a 24 h Holter ambulatory electrocardiographic (ECG) monitor, 33 (Group II) had a documented episode of sustained ventricular tachycardia or fibrillation, or both, and 20 (Group III) had angina pectoris but no ventricular tachycardia or fibrillation. Eight Group I survivors underwent programmed electrical stimulation or ECG signal averaging, or both. All Group II patients underwent 24 h Holter monitoring and ECG signal averaging to detect late potentials before programmed electrical stimulation. Group III patients underwent both 24 h Holter recording and coronary angiography. The 24 h ECG tapes were analyzed for ST segment changes, prematurity index and characteristics of ventricular premature depolarizations. Any ST depression greater than or equal to 1 mm for greater than 30 s was considered to be a reflection of silent ischemia, and the induction of ventricular tachycardia or fibrillation by programmed electrical stimulation or the presence of late potentials, or both, was considered to be a reflection of the arrhythmia substrate. Silent ischemia preceded ventricular tachycardia in only 2 (14%) of the 14 Group I patients. The prematurity index was less than 1 in only 18% of ventricular tachycardia episodes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diagnostic value of methods of ventricular and auricular stimulation in the evaluation of tachycardia

The diagnostic value of programmed pacing in the investigation of tachycardia (greater than 5 premature complexes) was studied in 155 patients admitted for evaluation of dizzy attacks and/or tachycardia by determining a relationship between the induction of tachycardia by endocavitary pacing and the presence of spontaneous attacks on ECG and/or 24 hour Holter monitoring. Right atrial and ventricular programmed pacing comprised: an extrastimulus during sinus rhythm (method I), during paced rhythm (method II), 2 extrastimuli during sinus rhythm (method III) and paced rhythm (method IV). The protocol was applied in 20 cases of spontaneous atrial tachycardia (AT) and 40 patients without tachycardia, and in 20 cases of spontaneous sustained ventricular tachycardia (VTS) (Group A), 15 cases of non-sustained ventricular tachycardia (VTNS) (Group B), 20 cases of ventricular doublets or triplets on Holter monitoring (Group C) and 40 patients without ventricular arrhythmias. The following results were obtained: At atrial level, method I was associated with a 75% sensitivity and a 62.5 p. 100 specificity when the triggering of atrial echos was considered. It was difficult to induce AT with methods I, II and III (sensitivity 15, 20 and 45 p. 100 - but they were very specific (greater than 90 p. 100). The induction of echos with methods II, III and IV was very sensitive but not specific and could not be retained as a pathological criterion. Using method IV, only the triggering of sustained AT could be considered to have a good specificity (90 p. 100), but sensitivity remained low (30 p. 100). At ventricular level, more aggressive methods were needed to induce an arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Value of transesophageal programmed atrial stimulation in the evaluation of unexplained cerebrovascular accidents

Certain embolic cerebrovascular accidents can be explained by the development of paroxysmal atrial fibrillation. When noninvasive complementary investigations are negative, programmed atrial stimulation can be proposed to detect increased atrial vulnerability. The objective of this study was to evaluate the reliability of this method performed via a transoesophageal approach in 59 subjects presenting with an embolic cerebrovascular accident and who were in sinus rhythm at the time of the accident. Seven of these patients had a history of paroxysmal atrial fibrillation (AF) or atrial tachycardia (AT) (group I). Three of these seven patients also presented AV nodal reentrant junctional tachycardia. The other 52 patients had no history of arrhythmia and their Holter recording did not reveal any episodes of sustained atrial tachycardia (group II). Transoesophageal programmed atrial stimulation used up to 2 extrastimuli under baseline conditions and during Isuprel infusion. The following results were obtained: sustained atrial tachycardia (> 1 min) was induced in all patients of group 1, 3 of them also presented inducible junctional tachycardias. 14 patients of group II (27%) presented inducible supraventricular tachycardia: atrial tachycardia in 7 cases. Patients in group II with inducible AT presented either heart disease (n = 3) or minor abnormalities on the Holter recording (runs of atrial premature complexes or sinus pauses (n = 3). Two of these patients subsequently developed sustained atrial fibrillation during follow-up. In 25 patients with normal Holter recording and no heart disease, programmed atrial stimulation induced junctional tachycardia in 4 cases. In conclusion, transoesophageal electrophysiological investigation is a useful way to identify various forms of supraventricular tachycardia able to explain an embolic cerebrovascular accident. The considerable incidence of inducible AV nodal reentrant junctional tachycardia must be emphasized, while the incidence of atrial fibrillation is much lower than during intracardiac investigations.     

Ambulatory electrocardiographic correlates of ventricular inducibility during programmed electrical stimulation

To determine the relation between spontaneous and induced ventricular arrhythmias, ambulatory electrocardiographic (Holter) monitoring and programmed electrical stimulation were performed in 48 adult patients with suspected life-threatening ventricular arrhythmias. Nine had no inducible arrhythmia, 11 demonstrated 1 to 2 beats of intraventricular reentry, 19 exhibited non-sustained ventricular tachycardia and 9 exhibited sustained ventricular tachycardia during electrophysiologic studies. Patients without arrhythmia inducibility had a high incidence of multiformity (56%) and bigeminy (44%), but a low incidence of either couplets (11%) or spontaneous ventricular tachycardia (11%) on Holter monitoring. An increasing incidence of all "complex" ectopic features was found with increasing degrees of ventricular inducibility. In patients with inducible sustained ventricular tachycardia, multiformity was present in 100%, bigeminy and couplets in 89% and spontaneous ventricular tachycardia in 78%. Premature ventricular complex frequency, couplet frequency and the repetition index (the ratio of couplets to premature ventricular complexes) were also found to be directly correlated with the degree of ventricular inducibility. Three quantitative arrhythmia variables were identified which predicted ventricular tachycardia inducibility. Seven (78%) of 9 patients with a mean premature ventricular complex frequency of 100 or more/1,000 normal beats, 11 (85%) of 13 with a mean couplet frequency of 1 or more/1,000 normal beats and 19 (83%) of 23 with a mean repetition index value of 15 or more/1,000 premature ventricular complexes proved to have inducible ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)     

The prognostic value of the changes in the mode of ventricular tachycardia induction noted during therapy with a marked reduction of ventricular ectopic activity

The prognostic significance of changes in the mode of induction of ventricular tachycardia (VT) noted during therapy was studied in 49 patients with sustained VT or ventricular fibrillation. Before treatment, all patients had inducible sustained VT by programmed stimulation (one to three extrastimuli) and frequent (greater than or equal to 30/hr) ventricular premature complexes (VPCs). On the discharge regimen, VT was no longer inducible by programmed stimulation in 22 patients (group 1). Twenty-seven patients (group 2) with persistent induction of VT despite extensive serial drug testings were discharged on a regimen that resulted in a marked reduction of VPCs on Holter monitoring (greater than or equal to 50% reduction of VPCs, greater than or equal to 90% reduction of couplets, and abolition of nonsustained VT). The modes of induction at baseline and on the discharge regimen were compared in each patient in group 2. Induction of VT was more difficult, requiring more aggressive stimulation protocol in 5 of 27 patients, unchanged in 14 patients, and easier in 8 patients. The duration of follow-up was 20 +/- 13 months (mean +/- SD). Arrhythmia-free survival rates at 6, 12, 18, and 24 months were 95%, 89%, 82%, and 73% in group 1, 92%, 84%, 75%, and 75% in group 2, 93%, 83%, 77%, and 69% in 27 patients with noninducibility or harder induction, and 95%, 90%, 79%, and 79% in 22 patients with the same or easier induction, respectively. The differences were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Programmed stimulation in patients with malignant ventricular arrhythmia. II: Individual optimization of anti-arrhythmia therapy

The major purpose of programmed ventricular stimulation in patients with malignant ventricular arrhythmias (sustained ventricular tachycardia/ventricular fibrillation) is not the diagnostic or prognostic evaluation but the individual optimization of antiarrhythmic therapy. For successful antiarrhythmic treatment, the choice of an adequate parameter of efficacy is of outstanding relevance: in patients with frequent daily episodes of malignant ventricular arrhythmias, proper treatment can be based on Holter monitoring; however, in patients with infrequent but life-threatening attacks, Holter monitory appears to be inadequate and programmed stimulation is the method of choice for proper treatment decisions. A total of 394 serial pharmaco-electrophysiological studies was performed in 82 patients with inducible sustained ventricular tachycardia or ventricular fibrillation. During the acute serial studies, one drug was tested each subsequent day using short-term intravenous infusions. The only criterion for drug efficacy was prevention of inducible sustained ventricular tachycardia or ventricular fibrillation that had been reproducibly initiated under control conditions before antiarrhythmic treatment. At least one preventive drug was found in approximately 2/3rd of the patients. Following serial acute studies using intravenous administration, an effective agent was selected and given orally. Programmed stimulation was repeated usually after three days demonstrating reproducibility of preventive efficacy in 90% of the trials. During a subsequent follow-up period of an average of 15 months, the number of acute events (9%) including sudden death or life-threatening recurrences of malignant ventricular arrhythmias was significantly reduced as compared to patients with non-optimized therapy (54%; p less than 0.05). The number of cardiac deaths due to progressive heart failures was not significantly different in patients placed on optimized or non-optimized antiarrhythmic treatment.     

Prognostic implications of complex ventricular ectopy in patients with and without structural heart disease. A study based on programmed electrical stimulation

Fifty-six patients with complex ventricular premature beats (Lown grade IVa, IVb), but no evidence of ventricular tachycardia on 48 hours of continuous monitoring were evaluated by programmed electrical stimulation. Thirty patients had coronary atherosclerotic heart disease, 3 had valvular heart disease, 2 had cardiomyopathy and 21 had no structural heart disease. Programmed stimulation identified two groups of subjects: Group I comprised 11 patients in whom ventricular tachycardia was induced and Group II comprised 45 patients (which included 21 patients without heart disease) in whom no ventricular tachycardia was induced. The incidence of left ventricular dysfunction (ejection fraction less than 40%) was significantly higher in Group I as compared to Group II (P less than 0.001). There was, however, no difference between the grade of ventricular ectopy, HV interval or the incidence of bundle branch block between the 2 groups. Patients with inducible ventricular tachycardia (Group I) were put on laboratory directed anti-arrhythmic drug therapy. Patients without inducible tachycardia (Group II) were not given anti-arrhythmic therapy. The patients were followed up for 34 +/- 10 months. The incidence of sudden death (36.3% vs 6.6%, P less than 0.001) was significantly higher in Group I as compared to Group II. No patients without structural heart disease died during the follow-up. Programmed electrical stimulation fails to induce ventricular tachycardia in patients with complex ventricular ectopy but no structural heart disease. It is, however, possible to define a high risk subset in patients with structural heart disease and complex ectopy. The high risk patients with inducible ventricular tachycardia do not seem to benefit by anti-arrhythmic drugs, which may independently increase the risk of sudden death in treated patients. Patients in whom ventricular tachycardia is not inducible have better left ventricular function, a good long-term prognosis and do not require anti-arrhythmic agents.     

Flecainide: steady state electrophysiologic effects in patients with remote myocardial infarction and inducible sustained ventricular arrhythmia

The effect of flecainide in 24 patients with inducible sustained ventricular arrhythmia and a history of remote myocardial infarction was determined. Flecainide was administered in oral doses individually adjusted to suppress all spontaneous ventricular tachycardia and 80% of ventricular premature complexes on 24 hour ambulatory (Holter) electrocardiography. Antiarrhythmic therapy, as assessed by Holter monitoring, was adequate in 20 (83%) of the study patients at a mean dose of 144 +/- 28 mg every 12 hours; the mean plasma flecainide level was 583 +/- 329 ng/ml. In 18 patients, the mean sinus cycle length, sinus node recovery time and atrial, atrioventricular nodal and ventricular refractory periods were unchanged. The AH interval increased by 15 +/- 15%, the HV interval by 35 +/- 32% and the QRS duration by 24 +/- 21%. Toxicity or failure to suppress ventricular premature complexes and ventricular tachycardia by Holter monitoring precluded electrophysiologic study with flecainide in four patients; two patients refused electrophysiologic study with flecainide for nonmedical reasons. Ventricular tachycardia was not inducible in 4 (22%) of 18 patients receiving flecainide. Sustained arrhythmia remained inducible in 14 patients (78%) despite evidence of antiarrhythmic efficacy on Holter monitoring, but the rate of the induced ventricular tachycardia was slower and symptoms were alleviated during ventricular tachycardia in 10 (56%) of 18 patients. The 4 patients who had no inducible ventricular tachycardia with flecainide, and the 10 patients who had inducible ventricular tachycardia with a longer cycle length and alleviation of their symptoms, have been followed up as outpatients for 16 +/- 7 months.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of Holter monitoring in patients with recurrent sustained ventricular tachycardia: an electrophysiologic correlation

The significance of spontaneous ventricular premature depolarization (VPD) frequency and severity in patients with sustained ventricular tachycardia undergoing serial electrophysiologic studies (EPS) are unknown. Nineteen patients with sustained ventricular tachycardia were studied with 24-hour Holter recordings prior to control EPS and prior to each drug trial. Successful drug or surgical treatment (with the exception of amiodarone) was based upon noninducibility of ventricular tachycardia in the laboratory. Among the eight noninducible and nonamiodarone medically treated patients, two (25%) had significant VPD reduction and/or Lown class improvement. The remaining six (75%) had no change or worsening of Holter findings, despite noninducibility of sustained VT. Among the six amiodarone-treated patients, five of whom were persistently inducible prior to discharge, four (66%) had improved and two (33%) had worsened Holter findings compared to control. None of the five (100%) surgically managed patients were inducible postoperatively, and three of the five (60%) had no change or worsening of Holter findings. We conclude that (1) EPS are superior to Holter findings in assessing successful management; and (2) Holter findings may be concordant or discordant during EPS serial drug trials or following surgery and therefore cannot predict the success or failure of the intervention.     

Lack of prognostic implications of spontaneously occurring or stimulation induced atrial tachyarrhythmias in patients with dilated cardiomyopathy.

A prospective study was undertaken in 102 patients with idiopathic dilated cardiomyopathy to assess the significance of spontaneous and inducible atrial tachyarrhythmias (ATA). Twenty-six patients were in chronic atrial fibrillation (group I) and 76 patients were in sinus rhythm (group II); 14 patients in group II had a clinical history of ATA or episodes of ATA during Holter monitoring. An electrophysiological study was systematically performed. Programmed atrial stimulation was carried out in group II, and used up to two atrial premature stimuli from the right atrium at 2 cycle lengths (sinus cycle length--10%, 600 ms) and then one atrial extrastimulus under infusion of 1 to 4 micrograms. min-1 of isoproterenol. Programmed ventricular stimulation was performed in groups I and II. Sustained atrial tachyarrhythmia (ATA) was induced in 33 patients in group II (42%); isoproterenol infusion facilitated the induction of ATA in only one other patient, who had exercise-related ATA. Eleven patients in group II with spontaneous ATA had inducible sustained ATA. The sensitivity of programmed atrial stimulation to reproduce an ATA was 78.5% and its specificity 64.5%. Inducible ATA was related to a shorter atrial effective refractory period (209 +/- 25 ms vs 228 +/- 32, P less than 0.02). Inducible and spontaneous ATAs were related to older age but not to the existence of spontaneous or inducible ventricular tachycardia; they did not have prognostic significance: the left ventricular ejection fraction and the prognosis were similar in patients with spontaneous or inducible ATA and those without ATA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Day to day reproducibility of electrically inducible ventricular arrhythmias in survivors of acute myocardial infarction

Day to day reproducibility of the response to programmed ventricular stimulation has not been evaluated in survivors of acute myocardial infarction. Programmed ventricular stimulation was performed prospectively on 2 consecutive days in 56 patients on an average of 12 +/- 5 days (range 7 to 29) after an acute myocardial infarction. No patient had a history of documented or suspected sustained ventricular tachycardia or fibrillation occurring greater than 48 h after infarction. During initial programmed ventricular stimulation, 21 patients had induction of sustained ventricular tachycardia or fibrillation (Group I), and 35 patients had induction of either nonsustained ventricular tachycardia or no ventricular tachycardia (Group II). Repeat programmed ventricular stimulation in Group I patients induced sustained ventricular tachycardia or fibrillation in 16 of 21 patients (reproducibility 76%); the maximal induced response in the other 5 patients was nonsustained ventricular tachycardia in 2 patients and fewer than six repetitive ventricular responses in 3 patients. The day to day reproducibility was significantly higher for inducible sustained ventricular tachycardia of cycle length greater than or equal to 240 ms compared with rapid sustained ventricular tachycardia of cycle length less than 240 ms (100% versus 44%, p less than 0.009) or ventricular fibrillation (100% versus 43%, p less than 0.009). Repeat programmed ventricular stimulation in Group II patients did not induce sustained ventricular arrhythmias in 31 of 35 patients (reproducibility 89%). Thus, in survivors of acute myocardial infarction, inducible slow sustained ventricular tachycardia was a highly reproducible finding, whereas inducibility of rapid sustained ventricular tachycardia and ventricular fibrillation showed a significant day to day variability.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determinants of prognosis in idiopathic dilated cardiomyopathy as determined by programmed electrical stimulation

The incidence and prognostic significance of electrically induced ventricular arrhythmias were prospectively assessed in 42 patients with idiopathic dilated cardiomyopathy. All patients underwent 24-hour, long-term electrocardiographic (Holter) monitoring and 30 were analyzed by a signal-averaging vectorcardiographic procedure at entry into the study. Their response to programmed electrical stimulation during basic right ventricular pacing was investigated using 1 and 2 ventricular extrastimuli. A monomorphic tachycardia was not induced in any patient. In 36 patients (86%) polymorphic ventricular arrhythmias were initiated. Three or more induced consecutive ventricular premature complexes occurred in 9 patients (21%), nonsustained polymorphic ventricular tachycardia in 2 (4.8%) and ventricular fibrillation in 1 patient (2.4%). There was no association between electrically induced polymorphic ventricular arrhythmias and the degree of impairment of left ventricular function. Furthermore, the incidence of induced ventricular arrhythmias was not related to the Lown grade or to the total number of ventricular premature complexes during Holter monitoring. A late potential was detected by the averaged vectorcardiogram in only 1 of the 30 patients. During follow-up (mean 16 +/- 7 months) 7 patients died, 5 from chronic congestive heart failure and 2 from sudden cardiac death. No patient had an electrically induced arrhythmia of 3 or more ventricular premature complexes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Does syncope change the results of programmed ventricular stimulation in patients with previous myocardial infarction?

The induction of a ventricular tachycardia (VT) after myocardial infarction (MI) is associated with a high risk of VT and sudden death (SD) in asymptomatic patients; the purpose of the study was to know if syncope modifies the results of programmed ventricular stimulation (PVS) and the clinical consequences. METHODS: PVS using two and three extra stimuli delivered in two sites of right ventricle was performed in 1057 patients without spontaneous VT or resuscitated SD at least 1 month after an acute MI; 836 patients (group I) were asymptomatic and were studied for a low ejection fraction or nonsustained VT on Holter monitoring or late potentials; 228 patients (group II) were studied for unexplained syncope. The patients were followed up to 5 years of heart transplantation. RESULTS: Sustained monomorphic VT (< 280 b/min) was induced in 238 group I patients (28%) and 62 group II patients (29%); ventricular flutter (VT > 270 b/min) or ventricular fibrillation (VF) was induced in 245 group I patients (29%) and 42 group II patients (18%) (P < 0.05); PVS was negative in 353 group I patients (42%) and 124 (55%) group II patients (NS). The patients differ by their prognosis; cardiac mortality was 13% in group I patients and 34% in group II patients with inducible VT < 280 b/min (P < 0.01), 4% in group I patients and 13% in group II patients with inducible VF (P < 0.05), 5% in group I patients and 7% in group II patients with negative study (NS). In conclusion, syncope did not change the results of programmed ventricular stimulation after myocardial infarction. However, syncope increased significantly cardiac mortality of patients with inducible ventricular tachycardia, flutter or fibrillation.     

Prognostic value of early electrophysiologic studies for ventricular tachycardia recurrence in patients with coronary artery disease treated with amiodarone

Amiodarone was used in 86 patients with ventricular tachycardia (VT) (67 patients) or ventricular fibrillation (19 patients) secondary to coronary artery disease. The mean +/- standard deviation left ventricular ejection fraction was 30 +/- 12% (range 8 to 65%). Prior trials with 4 +/- 1.2 alternate antiarrhythmic agents had been unsuccessful. Amiodarone was loaded at dosages of 1,200 to 1,800 mg/day, with maintenance dosages of 400 to 600 mg/day. Drug efficacy was evaluated by programmed stimulation at 10 to 14 days in 68 patients. In 38 patients sustained VT or ventricular fibrillation was inducible (group I), whereas 30 patients (group II) had either no inducible VT (8) or had nonsustained VT induced (22). Holter monitoring was used to assess drug efficacy in 18 patients (group III). All patients were evaluated at 3- to 6-month intervals with Holter monitors for efficacy and a standard protocol for toxicity. During a long-term follow-up of 18 +/- 16 months, sudden death occurred in 5 patients and nonfatal arrhythmia recurrences were detected in 16. The actuarial probability of freedom from fatal and nonfatal arrhythmia recurrences at 24 months was 0.52 for group I, 0.97 for group II and 0.68 for group III. The mode of induction, rate change or hemodynamic tolerance of the induced ventricular tachycardia did not predict arrhythmia recurrence. Among the clinical variables analyzed, only an ejection fraction of less than or equal to 30% was identified as a significant predictor of arrhythmia recurrence. Nonsudden cardiac death occurred in 21 patients, including 19 from heart failure and 2 from myocardial infarction. Noncardiac death occurred in 7 patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Flecainide: electrophysiologic and antiarrhythmic properties in refractory ventricular tachycardia

Twenty-two patients with coronary artery disease and spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) underwent intracardiac electrophysiologic evaluation and, when possible, ambulatory monitoring before and after therapy with flecainide (mean dose 418 +/- 87 mg [mean +/- standard deviation]). An average of 4 antiarrhythmic agents were used and were unsuccessful before therapy with flecainide was begun. During 64 +/- 16 hours of control Holter monitoring in 16 patients, all had 1 or more salvos of VT, as well as ventricular premature complexes (VPCs). Programmed stimulation during the control period induced VT in 17 of 22 patients. After flecainide therapy, Holter monitoring showed elimination of all forms of VT in all but 1 patient, as well as significant reduction of paired VPCs by 95% (p less than 0.03) and single VPCs by 70% (p less than 0.005). Electrophysiologic study during flecainide therapy showed significant increases in AH, HV, PR, QRS and QTc intervals, and the ventricular effective refractory period. Programmed stimulation in 17 patients taking flecainide, with a mean plasma level of 1,075 +/- 521 ng/ml, showed ablation of inducible VT in only 2 patients, a worsening in 5 and continued VT inducibility in 10. Adverse effects that required drug withdrawal were infrequent and encountered in patients who received higher drug levels: 1 patient with congestive heart failure and 1 with severe sinus bradycardia. Thus, although flecainide suppresses complex ventricular arrhythmias on Holter recordings, it rarely alters the response to programmed stimulation. Caution is recommended in its use for recurrent sustained VT or VF and in the interpretation of electrophysiologic studies until the predictive value of programmed stimulation with flecainide therapy is established.