Value of Holter monitoring in identifying risk for sustained ventricular arrhythmia recurrence on amiodarone

Emerging role of digital technology and remote monitoring in the care of cardiac patients

Current available mobile health technologies make possible earlier diagnosis and long-term monitoring of patients with cardiovascular diseases. Remote monitoring of patients with implantable devices and chronic diseases has resulted in better outcomes reducing health care costs and hospital admissions. New care models, which shift point of care to the outpatient setting and the patient's home, necessitate innovations in technology.

Risk stratification for arrhythmic events in patients with nonischemic dilated cardiomyopathy and nonsustained ventricular tachycardia: role of programmed ventricular stimulation and the signal-averaged electrocardiogram

OBJECTIVES

This study investigated prediction of arrhythmic events by the signal-averaged electrocardiogram (ECG) and programmed stimulation in patients with nonischemic dilated cardiomyopathy.

BACKGROUND

Risk stratification in patients with nonischemic dilated cardiomyopathy remains controversial.

METHODS

Eighty patients with nonischemic dilated cardiomyopathy and spontaneous nonsustained ventricular tachycardia underwent signal-averaged electrocardiography (both time-domain and spectral turbulence analysis) and programmed stimulation. All patients were followed up for a mean of 22 +/- 26 months.

RESULTS

Sustained monomorphic ventricular tachycardia was induced in 10 patients (13%), who all received amiodarone. The remaining 70 patients were followed up without antiarrhythmic therapy. Of the 80 patients, 15% had abnormal findings on the time-domain signal-averaged ECG, and 39% had abnormal findings on spectral turbulence analysis. Time-domain signal-averaged electrocardiography had a better predictive accuracy for induced ventricular tachycardia than spectral turbulence analysis (88% vs. 66%, p < 0.01). During follow-up, there were 9 arrhythmic events (5 sudden deaths, 4 spontaneous ventricular tachycardia/fibrillation) and 10 nonsudden cardiac deaths. Cox regression analysis showed that no variables predicted arrhythmic events or total cardiac deaths. The 2-year actuarial survival free of arrhythmic events was similar in patients with or without abnormal findings on the signal-averaged ECG or induced ventricular tachycardia.

CONCLUSIONS

In patients with nonischemic dilated cardiomyopathy, 1) there is a strong correlation between abnormal findings on the time-domain signal-averaged ECG and induced ventricular tachycardia, but both findings are uncommon; and 2) normal findings on the signal-averaged ECG, as well as failure to induce ventricular tachycardia, do not imply a benign outcome.

Invasive and noninvasive methods to predict the long-term efficacy of amiodarone: a compilation of clinical observations using meta-analysis

BACKGROUND

The method of choice to predict the long-term efficacy of amiodarone in the treatment of complex ventricular arrhythmias is unknown. Whether electrophysiological testing or Holter monitoring better predicts long-term outcome is controversial.

METHODS AND RESULTS

We performed a meta-analysis of trials using electrophysiological testing or electrocardiographic monitoring to predict the efficacy of amiodarone in patients with sustained ventricular tachycardia. Arrhythmia recurrence data were combined after homogeneity testing across trials. Bayesian estimates and 95% credibility intervals were constructed to compare the arrhythmia-free probability among groups. Nine studies using electrophysiological testing (351 patients) and three using Holter monitoring (167 patients) met criteria for inclusion determined a priori. The combined arrhythmia-free probability estimate and credibility intervals were 0.86 (0.78-0.92) for patients rendered noninducible and 0.81 (0.73-0.87) for patients with abolition of ventricular tachycardia during Holter monitoring on amiodarone. With this primary analysis, there was no significant difference between the predictive value of noninducibility during electrophysiological testing and abolition of ventricular tachycardia with Holter. However, if only those electrophysiological studies using at least triple extrastimuli were included, arrhythmia-free probability for patients rendered noninducible increased to 0.96 (0.88-0.99), significantly better than noninvasive testing.

CONCLUSIONS

Noninducible ventricular tachycardia during electrophysiological testing and abolition of ventricular tachycardia during electrocardiographic monitoring on amiodarone appear equally predictive of long-term amiodarone success, but this conclusion seems dependent on the stimulation protocol used. Although the yield is lower (compared to Holter monitoring), ventricular tachycardia rendered noninducible with a stimulation protocol using triple extrastimuli is the most highly predictive test of long-term amiodarone efficacy.

Usefulness of Holter monitoring in predicting efficacy of amiodarone therapy for sustained ventricular tachycardia associated with coronary artery disease

The ability of Holter monitoring to predict clinical events during amiodarone therapy was evaluated in 83 patients with coronary artery disease and inducible monomorphic ventricular tachycardia. Sixty-four patients (77%) had significant ventricular ectopy activity (> or = 10 ventricular premature complexes [VPCs]/hour) at baseline, and 19 (23%) did not; patients were similar in age (63 and 65 years, respectively; p = 0.24) and ejection fraction (31 and 32%, respectively; p = 0.75). Over a mean of 23 +/- 17 months, there was no difference in arrhythmia recurrence (33 and 26%; p = 0.89) or sudden death (16 and 20%; p = 0.94) in patients with and without significant ectopy, respectively. In patients with significant ectopy, amiodarone decreased VPC frequency from baseline to 2 weeks, but not from 2 to 6 weeks. Forty-two patients had > 85% reduction in ectopy at 2 weeks; 20 patients did not. However, this reduction of simple VPCs did not predict a decrease in arrhythmic recurrence (29 vs 40%; p = 0.59) nor sudden death (25 vs 11%; p = 0.56) in patients with and without VPC suppression, respectively. Forty-five patients had Holter monitoring at 6 weeks. Twenty-one patients (47%) had > 95% suppression of ectopy, and 24 did not. Neither the recurrence (38 vs 38%; p = 0.54) nor sudden death (33 vs 13%; p = 0.45) rate was predicted by the degree of VPC suppression. Amiodarone is a powerful suppressant of VPCs, but Holter suppression of this ectopic activity is not predictive of clinical outcome.

Sudden cardiac death: etiologies, pathogenesis, and management

Sudden death claims an estimated 350,000 lives per year in the United States. When death occurs within 1 hour of the onset of symptoms, 90% are the result of ventricular tachyarrhythmias. The majority of victims are middle-aged men with coronary artery disease, but in approximately 25%, sudden death is the presenting manifestation of their problem. In some populations, the detection of premature ventricular complexes (PVCs) by ambulatory monitoring is predictive of an increased risk of sudden death. However, the arrhythmia that best predicts this risk is unclear, and ambient arrhythmias are only a modest marker of this risk. Therapy to suppress asymptomatic PVCs has not been shown to be effective in preventing sudden death, and in some cases, lethal arrhythmias can be prevented without significant effects on ambient arrhythmias. Other risk markers such as depressed left ventricular function and the presence of low-amplitude, long-duration, late potentials recorded on a signal averaged electrocardiogram are more powerful predictors of risk than are PVCs. These latter findings in particular support the presence of areas of slow electrical conduction (a requirement for reentrant mechanism arrhythmias) and suggest that an abnormal electrical environment or "substrate" is the most important factor in this problem. The management of patients at risk for sudden death is controversial. While postinfarct survivors with arrhythmias constitute a population at increased risk, the absolute risk is only about 5% in the first year and has not been shown to be improved by conventional antiarrhythmic drugs. Small study size, arrhythmia variability, ill-defined end points, and proarrhythmia may partially explain this apparent lack of efficacy. The prophylactic use of antiarrhythmic drugs other than beta-blockers to prevent sudden death in asymptomatic populations at risk is therefore of unproven benefit. By contrast, patients who have survived a life-threatening arrhythmia unrelated to an acute myocardial infarction have an approximately 30% risk of recurrence in the following year. In these patients, the use of ambulatory monitoring to guide therapy is limited by the high incidence of false-negative responses (lethal arrhythmia recurrence despite ambient arrhythmia suppression) and the lack of frequent spontaneous arrhythmias in many patients. In this patient population, electrophysiological testing can be used to prognosticate recurrence and gain insight into arrhythmia mechanism, stability, and hemodynamic tolerance. The technique is also useful in guiding both pharmacological and nonpharmacological therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Values and limitations of programmed stimulation and ambulatory monitoring in the management of ventricular tachycardia

Programmed stimulation (PES) and ambulatory electrocardiographic (Holter) monitoring are both widely used to evaluate the efficacy of antiarrhythmic drugs in patients with recurrent ventricular tachycardia (VT). PES is sensitive but nonspecific, and Holter is specific but insensitive. A failure to suppress ventricular premature complexes (VPCs) on Holter during drug therapy predicts a poor outcome. A suppression of VPCs by drug therapy, however, does not preclude a poor outcome. If VT is no longer induced by PES during drug therapy, the patients will have a good outcome. A persistent induction of VT during drug therapy, however, does not preclude good outcomes. Therefore some investigators have suggested alternative PES efficacy criteria such as the changes in the rate of induced VT during therapy. Further studies should be conducted to confirm this. Because both methods have values and limitations, a combined use of the 2 methods is recommended to improve the clinician's ability to predict the outcome of antiarrhythmic therapy. Studies designed to prove that 1 method is better than the other may prove futile.

The premise, promise, and perils of the prevention of lethal ventricular tachyarrhythmias

Sudden cardiac death caused by ventricular tachyarrhythmias claims about 360,000 lives a year in the United States. The premature ventricular complex (PVC) hypothesis has been the cornerstone for understanding this problem, but it is now recognized as an incomplete explanation for this catastrophy. The recognition of the importance of structural heart disease in this process has led to the development of the Substrate Hypothesis as an alternative explanation. In this construct, PVCs may trigger lethal arrhythmias but only if an abnormal electrophysiologic substrate is present. This hypothesis more completely describes the pathophysiology of the process, provides the basis for understanding the value and limitations of the techniques used for risk assessment and management, and helps clarify the potential endpoints and potential adverse effects of therapy to prevent arrhythmias. Since no single diagnostic technique is ideal and no therapeutic modality is universally effective, an approach to the management of this problem must be multidimensional and based on a firm understanding of the actual risk of a life threatening arrhythmia, the potential but unproven benefits and uncertain endpoints of drug therapy, the cost, and the potential for arrhythmia exacerbation or significant side effect.

Empiric amiodarone versus "ineffective" drug therapy in patients with refractory ventricular tachyarrhythmias

Because of its presumed unique efficacy, amiodarone (AM) is often used to treat patients whose sustained ventricular tachyarrhythmias (VT/VF) appear to be drug-refractory. To examine the efficacy of AM in such patients, we performed a retrospective analysis of 77 patients with drug-refractory VT/VF treated with either empiric AM or with drugs predicted during electrophysiological (EP) testing to be ineffective (ID). To qualify for the study, patients had to have spontaneous, symptomatic VT/VF, and persistently inducible VT during serial EP testing with drugs. All 77 patients were offered therapy with AM. Those who refused were treated with ID, whenever possible, an ID was selected which "improved" the EP study compared to baseline. Originally, 68 patients elected AM and nine elected ID. Because of drug intolerance or inefficacy, 10 patients crossed over during the course of the study; a total of 71 patients were followed on AM for 15.7 +/- 11.0 months, and 16 on ID for 17.8 +/- 10.8 months (mean +/- SD). During follow-up, the cumulative recurrence of VT/VF at 6, 12, and 24 months for AM versus ID was 16 +/- 5% versus 44 + 12% (P less than 0.002), 32 +/- 6% versus 44 +/- 12% (NS), and 41 +/- 7% versus 44 +/- 12% (NS) (+/- SE). The recurrence of VT was significantly lower in the AM group only for the first 6 months of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone in the management of cardiac arrhythmias: current concepts

This article reviews current information on the clinical pharmacology, therapeutic utility, and adverse reactions of amiodarone, with emphasis on guidelines for its rational use.

Safety and efficacy of amiodarone. The low-dose perspective

Amiodarone has been reported to be a remarkably safe and effective drug in the European and South American experience but American investigators have published conflicting data. Since this disparity may be explained by a different dosing schedule, we prospectively evaluated the safety and efficacy of a low dose regimen in a group of 68 patients with cardiac arrhythmia resistant to conventional therapy, of whom 57 had manifested either ventricular tachycardia or fibrillation. All were loaded either intravenously (17) or orally, and maintained on an oral dose of 200 to 600 mg/day (mean daily dose 317 +/- 114 mg) and followed for 4 to 58 months (22 +/- 11). Results indicated that amiodarone was a safe and effective antiarrhythmic drug when used in lower doses.

Comparison of the characteristics of nonsustained ventricular tachycardia on Holter monitoring and sustained ventricular tachycardia observed spontaneously or induced by programmed stimulation

The characteristics of nonsustained ventricular tachycardias (VT) on Holter monitor recordings were compared with the characteristics of sustained VT noted spontaneously or induced by programmed stimulation in 50 patients with a history of spontaneous sustained VT. At baseline before antiarrhythmic therapy, all patients had nonsustained VT (triplets or longer) on Holter recordings and sustained VT inducible by programmed stimulation. The mean rate of the fastest nonsustained VT on Holter monitoring (150 +/- 52 beats/min) was significantly slower that that of induced sustained VT (246 +/- 56 beats/min) (p less than 0.001). Compared with nonsustained VT on Holter monitoring, sustained VT by programmed stimulation were faster in 45 of 50 patients, similar in 2 and slower in 3. There was a poor correlation between the rates of nonsustained VT and sustained VT (r = 0.2195). The duration of the longest nonsustained VT was fewer than 6 beats in 24 patients and 6 beats or more in 26. The mean rates of induced sustained VT were not significantly different between patients with shorter (fewer than 6 beats) and longer (6 or more beats) nonsustained VT. In 12 patients, the rate of spontaneous sustained VT was available. The rate of spontaneous sustained VT (217 +/- 59 beats/min) was similar to that of sustained VT by programmed stimulation (277 +/- 60 beats/min). There was a close correlation (r = 0.8036) between the rates of spontaneous and induced sustained VT. However, the rate of nonsustained VT on Holter monitoring (151 +/- 76 beats/min) was significantly slower than the rate of spontaneous sustained VT (p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone in patients with recurrent sustained ventricular tachyarrhythmias: results of programmed electrical stimulation and long-term clinical outcome in chronic treatment

Thirty-three patients with clinically recurrent ventricular tachyarrhythmias were treated with amiodarone (200 to 600 mg/day) during a mean follow-up period of 23.7 months. Prior to amiodarone therapy, sustained ventricular tachycardia or ventricular fibrillation was initiated in all patients at control electrophysiologic study; patients failed a mean of 5.7 drugs, as assessed by programmed electrical stimulation. At electrophysiologic study after a loading phase (1000 mg/day for 10 days), 10 patients had no inducible ventricular tachycardia, nine patients had nonsustained ventricular tachycardia, 13 patients had persistent sustained ventricular tachycardia, and one patient had ventricular fibrillation. Patients were continued on amiodarone alone regardless of the findings at the electrophysiologic study, and during follow-up patients with no inducible sustained ventricular tachycardia or fibrillation on amiodarone had no recurrent arrhythmias or sudden death. Six of 14 patients (43%) with sustained ventricular tachyarrhythmias still inducible had recurrent ventricular tachycardia/fibrillation, and four of them died suddenly (29%). Programmed electrical stimulation predicts a good clinical long-term outcome during amiodarone therapy. Patients with persisting fast tachyarrhythmias (cycle length less than or equal to 300 msec) on amiodarone and a low ejection fraction (less than 35%) seem to have a higher incidence of sudden death. In these patients, therapeutic approaches such as antiarrhythmic surgery or implantation of antitachycardia devices should be considered.

Combination of tocainide and quinidine for better tolerance and additive effects in patients with coronary artery disease

The efficacy and tolerance of tocainide used alone and in combination with quinidine were studied in 20 patients with coronary artery disease and frequent (greater than 30/h) ventricular premature complexes. Holter electrocardiographic monitoring was performed at baseline and during therapy with tocainide alone, quinidine alone and a combination of tocainide and quinidine. During single drug therapy, the dose of tocainide was 1,680 +/- 437 mg/day and that of quinidine was 1,340 +/- 235 mg/day. During combination therapy, with smaller doses of tocainide (1,350 +/- 394 mg/day) and quinidine (1,060 +/- 268 mg/day) in many patients, no patient had side effects. At baseline before therapy, the mean ventricular premature complexes/h were 629 +/- 567, couplets/h were 23.9 +/- 29.7 and nonsustained ventricular tachycardias/24 h were 60.5 +/- 152.2. Compared with baseline values (100%), the frequency of ventricular premature complexes was reduced to 33 +/- 44% with quinidine, 39 +/- 30% with tocainide and 10 +/- 16% with combination therapy (p less than 0.01 for combination versus quinidine or tocainide alone; p = NS for quinidine versus tocainide). Individually, an effective regimen (greater than 83% reduction of ventricular premature complexes and abolition of nonsustained ventricular tachycardia) was found in 3 (15%) of 20 patients receiving tocainide alone, in 6 (30%) receiving quinidine alone and in 16 (80%) receiving combination therapy (p less than 0.01 for tocainide versus combination, quinidine versus combination; p = NS for tocainide versus quinidine). Thus, the antiarrhythmic effects of quinidine and tocainide are additive.(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)

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)

Asymptomatic telephone ECG transmissions as an outpatient surveillance system of ventricular arrhythmias: relationship to quantitative ambulatory ECG recordings

Although ambulatory ECG recordings provide quantitative information in the follow-up of patients with ventricular arrhythmias, they are performed infrequently, potentially missing serious arrhythmias in the unmonitored periods. Telephone ECG systems offer "real-time" ECG information, theoretically functioning as an arrhythmia surveillance system. Thus we incorporated frequent telephone ECG transmissions in two antiarrhythmic drug protocols. The first investigation was designed to show the relationship of telephone and ambulatory ECGs in patients with frequent ventricular tachycardia (VT). The second protocol selected patients with "nonlife-threatening" frequent premature ventricular complexes (PVCs) in whom a second placebo period was instituted to simulate the clinical situation of asymptomatic arrhythmia increase. In both drug trials there was a strong linear relationship between the log-transformed PVC counts of telephone ECG and concomitant PVC, couplet, and VT frequencies on ambulatory ECG. In the VT population, greater than or equal to 1 PVC on telephone ECG reflected the presence of VT on ambulatory ECG (sensitivity 87%; specificity 77%). In the second study, telephone ECG transmissions with PVCs on three consecutive transmissions reflected the change from less than or equal to 10 PVCs/hour to greater than or equal to 40 PVCs/hour on ambulatory ECG within 48 hours. These data support the concept that daily surveillance by means of telephone ECG provides arrhythmia information of qualitative clinical relevance.

Management of refractory sustained ventricular tachycardia with amiodarone: a reappraisal

We examined the value of clinical variables, chronic 24-hour ambulatory ECG monitoring, and chronic electrophysiologic (EP) testing in 49 patients with recurrent and refractory sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) treated with chronic oral amiodarone in order to develop a prospective approach to the management of these patients. All patients underwent control EP studies followed by continuous telemetric cardiac monitoring during oral amiodarone administration (mean duration 29 +/- 6 days, mean dose 739 +/- 230 mg). Follow-up 24-hour ambulatory ECG monitoring and EP studies were performed. Thirty VT recurrences occurred in the first 4 weeks of amiodarone therapy (total incidence, 61%), with the majority (55%) in the first 3 weeks of treatment. During long-term follow-up (1 to 42, mean 15 +/- 12 months), there were 12 symptomatic VT/VF recurrences (incidence 24%). There was a higher incidence of VT recurrences if patients had inducible sustained or nonsustained VT at chronic EP study (p less than 0.01), or complex ventricular arrhythmias on ambulatory ECG monitoring (p less than 0.05). The sensitivity, specificity, and predictive accuracy of chronic EP testing and 24-hour ambulatory ECG monitoring were 100%, 35%, and 51%, and 58%, 84%, and 78%, respectively. Chronic EP testing correctly identified all patients who had their arrhythmia suppressed by amiodarone on long-term follow-up, while 42% of all VT recurrences occurred in patients without complex ventricular arrhythmias on 24-hour ambulatory ECG monitor.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

The use of ambulatory monitoring in the prognostic evaluation of patients with sustained ventricular tachycardia treated with amiodarone

We recently reported a retrospective experience with serial Holter monitoring as a guide to therapy in patients with sustained ventricular tachycardia treated with amiodarone. To confirm and substantiate these findings, a prospective study was designed that included baseline 24 hr Holter monitoring and serial Holter monitoring after 1 week of therapy with amiodarone. Fifty-two patients with documented sustained ventricular tachycardia who manifest nonsustained ventricular tachycardia on baseline Holter monitoring were treated with amiodarone. Thirty-four patients (group I) had nonsustained ventricular tachycardia completely suppressed and 18 patients (group II) had continued nonsustained ventricular tachycardia on serial Holter monitoring performed on days 8, 9, and 10 of therapy. At 11.6 +/- 1.0 (mean +/- SE) months follow-up, three (9%) group I patients and 12 (67%) group II patients had recurrent sustained ventricular tachycardia or sudden cardiac death (p less than .01). The sensitivity, specificity, positive and negative predictive value, and predictive accuracy of ventricular tachycardia on 24, 48, and 72 hr Holter monitoring over days 8, 9, and 10 for predicting recurrent sustained ventricular tachycardia or sudden cardiac death were analyzed. The positive and negative predictive values were 89% and 84%, 69% and 89%, and 67% and 91% for 24, 48, and 72 hr Holter monitoring, respectively. Overall predictive accuracy was 85%, 83%, and 83%, respectively. We conclude that early Holter monitoring is useful in assessing the clinical efficacy of amiodarone in patients with sustained ventricular tachycardia who manifest nonsustained ventricular tachycardia on baseline Holter monitoring.

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)

Amiodarone: value of programmed electrical stimulation and Holter monitoring

The value of programmed electrical stimulation (PES) and Holter monitoring in the assessment of amiodarone efficacy was reviewed. Many physicians have been disturbed by the persistent inducibility of arrhythmias in patients treated with amiodarone, who nevertheless do very well during the follow-up period. Noninducibility was associated with a favorable prognosis among 366 VT patients. Eighty-eight (24%) were noninducible on amiodarone, and 10% of these had recurrences, vs 39% in patients who remained inducible. Further, increased difficulty of induction with PES or induction of a slower or better tolerated VT may indicate a favorable outlook, and add to the value of PES. Few papers rigorously employed Holter monitoring in the assessment of amiodarone. In general, suppression of previously frequent arrhythmias implies excellent protection for patients with benign arrhythmias and moderate protection with malignant arrhythmias. By Holter assessment in 186 VT patients, arrhythmias were suppressed in 114 (61%), and 18% of these had recurrences vs 50% in patients whose arrhythmias were not suppressed. Studies attempting to correlate the results of PES and Holter monitoring in the same patients are lacking and may prove useful.

Utility of ambulatory electrocardiographic monitoring for predicting recurrence of sustained ventricular tachyarrhythmias in patients receiving amiodarone

The prognostic implications of changes in ventricular ectopic activity on serial 24 hour ambulatory electrocardiographic (Holter) recordings were prospectively evaluated in 107 patients with a history of sustained ventricular tachyarrhythmias treated with amiodarone for at least 30 days. Twenty-seven patients (25%) had insufficient ventricular ectopic activity (less than 10 ventricular premature complexes/h and no repetitive forms) on baseline Holter recordings for serial statistical analysis. In 53 (66%) of the remaining 80 patients, serial 24 hour Holter monitor recordings showed efficacy of treatment, defined as a 75% decrease in ventricular premature complexes, a 95% decrease in ventricular couplets and absence of ventricular tachycardia. During a mean follow-up period of 14.2 +/- 9.9 months, 34 (32%) of the 107 patients had recurrence of a sustained ventricular tachyarrhythmia. Holter recording correctly predicted nine recurrences and correctly identified 37 patients who did not experience a recurrence. Holter efficacy failed to predict recurrence of a sustained ventricular tachyarrhythmia in 16 patients, and 18 patients remained free of recurrence despite failure to achieve Holter efficacy. The positive predictive value of Holter monitoring efficacy was 33% and the negative predictive value was 70%; however, these differences were not statistically significant by chi-square analysis. Similar results were obtained using Holter recordings performed relatively early in therapy (6 weeks and 4 months). Of the 27 patients without significant ventricular ectopic activity on the baseline Holter recording, 9 had an arrhythmia recurrence despite continued infrequent ventricular premature complexes and no repetitive forms on subsequent recordings. The recurrence rate in this group (33%) was similar to the overall recurrence rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone-associated changes in human neutrophils

Amiodarone and its major metabolite, desethylamiodarone, were measured in the plasma, white blood cells (WBCs) and red blood cells (RBCs) of 14 patients receiving chronic amiodarone therapy. The mean plasma concentrations (+/- standard error of the mean) of amiodarone and desethylamiodarone were 2.4 +/- 0.6 and 1.6 +/- 0.4 microgram/ml, respectively. The drug level in the WBCs was 62 +/- 12 micrograms/g protein during the early loading phase and 106 +/- 33 micrograms/g protein during maintenance phase of amiodarone therapy. Desethylamiodarone concentration in the WBCs was 42 +/- 18 and 190 +/- 33 micrograms/g protein during the loading and maintenance phases, respectively. Although a trend in WBC to plasma concentration was seen, there was no linear correlation between these levels. In 1 patient with severe neuropathy, biopsy of the nerve and muscle showed high concentrations of both amiodarone and desethylamiodarone. Although there was a decrease in tissue drug levels, proportionately high tissue:plasma drug levels were detected at the time of necropsy approximately 6.5 months after amiodarone was discontinued in this patient. Neutrophils from all patients receiving chronic amiodarone therapy showed multiple myelin-like polymorphic inclusion bodies (onionoid bodies) upon electron microscopic examination. Our observations suggest that WBC drug concentrations and electron microscopic changes may provide a means of correlating tissue concentrations and of following patients receiving chronic amiodarone therapy.