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

Amiodarone therapy for sustained ventricular tachycardia after myocardial infarction: long-term follow-up, risk assessment and predictive value of programmed ventricular stimulation

We determine the value of the programmed ventricular stimulation (PVS) and of clinical, angiographic and electrophysiologic variables in assessing the long-term risk of arrhythmia recurrence in a group of coronary artery diseased patients presenting with a first episode of monomorphic sustained ventricular tachycardia (VT) treated with amiodarone. Mortality and arrhythmia recurrence rates were retrospectively assessed in 55 consecutive patients with previous myocardial infarction presenting with a first VT episode. Results of left heart catheterization, echocardiography and time-domain signal-averaging were collected. Patients underwent PVS after amiodarone oral loading and were classified according to inducibility before being all discharged on amiodarone (200 mg daily). The mean follow-up was 42+/-31 months. Total and cardiac mortality rates were 29% (16 patients) and 23% (13 patients) respectively. Sudden death (SD) occurred in nine patients (16%). VT recurred in 13 patients (23%). Sustained monomorphic VT was inducible in 40 patients (72%) after amiodarone loading. Neither total mortality (10/40 vs. 6/15) nor cardiac mortality (3/40 vs. 1/15) were significantly different between inducible and non-inducible patients. Recurrent VT rate was 27% (11/40 patients) for the inducible group and 13% (2/15 patients) for the non-inducible group (NS). SD occurred in 6/40 inducible patients (15%) and in 2/15 non-inducible patients (13%) (NS). Arrhythmic events occurred in 42% (17/40) inducible patients vs. 26% (4/15) non-inducible patients (P=0.07). Parameters correlated with outcome were ejection fraction (EF) (5 SD/11 patients with EF <0.3 vs. 4/44 with EF >0.3, P=0.003), mitral insufficiency (MI) (4 SD/10 patients with MI vs. 4/44 patients without MI, P=0.004) and age (65+/-9 years for patients with VT recurrence vs. 58+/-9, P=0.02). Although the risk stratification can be improved, reliable and safe long-term prediction of recurrence of malignant ventricular arrhythmia in individual patients cannot be made. Consequently, the systematic implantation of a cardioverter-defibrillator in case of a first episode of sustained VT occurring in coronary artery disease patients should be further debated.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Influence of Holter monitor and electrophysiologic study methods and efficacy criteria on the outcome of patients with ventricular tachycardia and ventricular fibrillation in the ESVEM trial

Because not all laboratories use the monitoring and stimulation protocols used in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, we reanalyzed the ESVEM patients' data using alternative, commonly used Holter monitor (HM) and programmed stimulation efficacy criteria to determine if different criteria would have changed the trial's conclusions. Also, because beta-blocker use and coronary artery disease frequency were not equally distributed between the two limbs in ESVEM, we reanalyzed the ESVEM data adjusting for the possible effect of these variables. In the HM limb, drug efficacy in the original ESVEM analysis was declared by reduction of total premature ventricular complexes (PVCs) by 70%, pairs by 80%, runs of 3 to 15 beats by 90%, and all ventricular tachycardia (VT) more than 15 beats by 100%. In this analysis, we examine outcome in subjects meeting two more stringent sets of criteria, (1) reduction of total PVCs by 70%, of pairs by 80%, and of all VT by 100% (new criteria set 1) and (2) reduction of total PVCs by 80%, of pairs by 90%, and of all VT by 100% (new criteria set 2). In electrophysiology (EPS) limb patients, we compared arrhythmia recurrence when efficacy was declared with triple extrastimuli as compared with maximally testing with double extrastimuli, and arrhythmia recurrence was compared in patients tested with identical versus any more aggressive protocol on drug than was used before drug. We also compared the predictive accuracy of zero versus 3 to 15, and 0 to 5, 6 to 10, and more than 10 induced beats on drug. Additionally, we compared predictive accuracy of the HM- and EP-guided limbs excluding patients on beta blockers and those with noncoronary disease. Lastly, to determine whether concordant results on HM and EPS testing would provide more accurate efficacy predictions than EP testing alone, HM recordings obtained in EPS-limb patients but not processed or used during the course of the EVSEM study were analyzed. The original ESVEM HM criteria, new set 1, and new set 2 yielded predicted drug efficacy rates of 77%, 68%, and 58%, respectively; however, arrhythmia recurrence rates were unchanged. Similarly, arrhythmia recurrence rates for patients tested with triple versus less than triple extrastimuli (p=.238), more aggressive versus identical protocols (p=.955), and 0 to 5 v 6 to 10 v more than 10 induced beats (p=.263) or 0 v 3 to 15 induced beats (p=.106) were unchanged. in the 215 (of 286) patients with coronary disease and not receiving beta blockers, there was still no difference in arrhythmia recurrence or mortality between the noninvasive and invasive limbs in ESVEM. Lastly, in patients with drug efficacy predictions by EPS testing, there was no difference in outcome in patients who had concordant versus discordant efficacy prediction by simultaneously obtained HMs. The use of more stringent testing methods and efficacy criteria would not have significantly improved the predictive accuracy of drug assessment by HM or EPS in the ESVEM trial. Additionally, excess noncoronary disease in EP-guided patients and excess beta-blocker used in HM-guided patients did not influence the results in the ESVEM trial.

QRS morphologies of the surface ECG of nonsustained ventricular tachycardias during holter monitoring compared with QRS morphologies of spontaneous sustained ventricular tachycardias

The purpose of this study was to compare electrocardiographic (ECG) morphologies of nonsustained ventricular tachycardias (VTs) during Holter monitoring with the ECG morphology of documented, sustained, monomorphic VTs during the spontaneous event of tachycardia in 14 patients (9 with coronary artery disease), in whom a sustained, spontaneous monomorphic VT had been documented in a 12-lead ECG. All patients had a 24-hour Holter ECG without antiarrhythmic medication. Channel 1 of the Holter ECG was compared with leads V1, V2, and V3, and channel 2 with leads V4, V5, and V6. The Holter ECG of 10 patients in whom the QRS complex during sinus rhythm was similar to the QRS complex in the corresponding ECG leads was accepted for analysis. In 8 of the 10 patients, nonsustained VTs were detected during Holter monitoring. In one of these eight, the ECG morphology of at least one nonsustained VT in the Holter recordings was identical with the sustained VTs. Thus, incidences and ECG morphologies of nonsustained VTs during Holter monitoring do not correlate closely with those of spontaneous sustained monomorphic VTs. Therefore, most ventricular runs during Holter monitoring may have a mechanism different from that of spontaneous sustained VTs.

Significance and incidence of concordance of drug efficacy predictions by Holter monitoring and electrophysiological study in the ESVEM Trial. Electrophysiologic Study Versus Electrocardiographic Monitoring

BACKGROUND

Selection of antiarrhythmic therapy may be based on either suppression of spontaneous ventricular arrhythmias assessed by Holter monitoring or by suppression of inducible ventricular arrhythmias during electrophysiological study. This study examines the frequency and significance of concordance of these two approaches in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial.

METHODS AND RESULTS

Twenty-four-hour Holter monitoring was performed in patients randomized to the electrophysiology limb of the ESVEM study at the time of the first drug trial and at the time of an effective drug trial. Holter monitors were available in 65% (146/226) of patients at the time of the first drug trial and in 93% (100/108) of patients at the time of an electrophysiology study predicting drug efficacy. There were no clinical differences between patients who had and those who did not have a Holter monitor. At the time of the first drug trial, concordance of Holter and electrophysiological predictions of drug efficacy was observed in 46% of patients (both techniques predicted efficacy in 23%; neither predicted efficacy in 23%). Discordant results were observed in 54% (Holter suppression without electrophysiological suppression in 44%; electrophysiological suppression without Holter suppression in 10%). At the time of an electrophysiology study predicting drug efficacy, 68 of the 100 patients without inducible ventricular tachyarrhythmias also had suppression of spontaneous ventricular arrhythmias on the Holter recorded at the time of the electrophysiological study. Neither arrhythmia recurrence nor mortality was significantly different in patients with suppression of both inducible and spontaneous ventricular arrhythmias compared with those with only suppression of inducible arrhythmias. Comparison of patients with suppression of both inducible and spontaneous ventricular arrhythmias with the 188 patients in the Holter limb, in whom efficacy was predicted by Holter monitoring only, revealed no difference in outcome.

CONCLUSIONS

In this population, (1) there is frequent discordance in prediction of drug efficacy and inefficacy between electrophysiological study and Holter monitoring; (2) a requirement to fulfill both Holter and electrophysiological efficacy criteria reduces the number of patients with an efficacy prediction; and (3) suppression of both spontaneous ventricular ectopy and inducible ventricular tachyarrhythmias does not identify a group with better 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.

Results of Holter ECG guided therapy for ventricular arrhythmias: the ESVEM trial

The Electrophysiological Study Versus Electrocardiographic Monitoring (ESVEM) trial randomized 486 patients with spontaneous sustained ventricular tachycardia (VT), ventricular fibrillation (VF) or unmonitored syncope, who manifested reproducibly inducible sustained ventricular arrhythmias by provocative stimulation and 10 or more premature ventricular contractions per hour on Holter monitoring, to two groups treated with pharmacotherapy guided by suppression of stimulation-inducible VT/VF or suppression of spontaneous or exercise induced ventricular arrhythmias. There was no difference over four years of follow-up in the rates of recurrence of arrhythmias, arrhythmic mortality, cardiac mortality, or mortality from any cause between the two groups of patients but more patients (77%) received pharmacotherapy in the group treated on the basis of suppression of spontaneous arrhythmias than the group treated on the basis of electrophysiological study. In this trial, rates of recurrence of arrhythmias were higher (37% at one year and 66% at four years) than generally reported, but cardiac and arrhythmia mortality were comparable or lower than generally reported. Of the seven agents tested, six were sodium channel blockers (imipramine, mexiletine, procainamide, propafenone, pirmenol, and quinidine) and the other was sotalol. Sotalol had a significantly higher rate of efficacy predictions by EPS (35%) than the others (15%) and a comparable rate by Holter monitor. Sotalol was significantly more efficacious in preventing recurrences, arrhythmic mortality, cardiac mortality, and total mortality than the other agents and it was better tolerated. Probability of successful long term therapy with a sodium channel blocker tested by electrophysiological study was low (5% at one year).(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of electrophysiologic testing with Holter monitoring to predict antiarrhythmic-drug efficacy for ventricular tachyarrhythmias. Electrophysiologic Study versus Electrocardiographic Monitoring Investigators

BACKGROUND

Invasive electrophysiologic study and noninvasive Holter monitoring (in conjunction with exercise testing) have both been used to evaluate the efficacy of antiarrhythmic drugs in patients with sustained ventricular tachycardia and in survivors of cardiac arrest. We directly compared these two approaches to the prediction of drug efficacy.

METHODS

A total of 486 patients who had documented ventricular tachyarrhythmias that were inducible during electrophysiologic study and 10 or more premature ventricular complexes per hour during Holter monitoring were randomly assigned to undergo serial testing of antiarrhythmic-drug efficacy by electrophysiologic study or Holter monitoring. The patients received up to six drugs in random order until one was predicted to be effective either in suppressing inducible arrhythmia (in the electrophysiologic-study group) or in suppressing premature ventricular complexes (in the Holter-monitoring group). The patients were then followed for recurrences of arrhythmia or death.

RESULTS

In the electrophysiologic-study group, 108 of 242 patients (45 percent) received a prediction of efficacy, as compared with 188 of 244 patients (77 percent) in the Holter-monitoring group (P < 0.001). Over a six-year follow-up period, there were 150 recurrences of arrhythmia and 46 deaths among the 296 patients receiving drugs predicted to be effective. Thirty-four of the deaths were from arrhythmic causes, and eight were from cardiac causes. There was no significant difference between the two study groups in the actuarial probabilities of these events. The risk of a recurrence of arrhythmia was significantly lower in patients who received sotalol than in those who received other antiarrhythmic drugs, and the risk was lower in those who had not previously failed to respond to antiarrhythmic drugs than in those who had.

CONCLUSIONS

Although Holter monitoring led to predictions of antiarrhythmic-drug efficacy more often than did electrophysiologic study in patients with sustained ventricular tachyarrhythmias, there was no significant difference in the success of drug therapy as selected by the two methods.

Ambulatory cardiac monitoring for the evaluation of antiarrhythmic agents

This decision-analysis model assesses ambulatory cardiac monitoring (ACM), ACM followed by exercise testing, and electrophysiologic studies (EPS) in the evaluation and selection of antiarrhythmic agents in postinfarct patients with malignant arrhythmias. With existing data, we find no consistent advantage for one method of drug testing over another, although ACM appears to require fewer resources than does EPS. More patients qualify for EPS, but this fact does not increase the proportion of patients for whom a drug can be identified. These methods may test different aspects of arrhythmia activity and drug response, and sequential use may provide additional benefits. Such benefits must be determined empirically.

Significance of the clinical presentation in ventricular tachycardia/fibrillation

We examined the hypothesis that clinical presentation in patients with sustained ventricular tachycardia/fibrillation (VT/VF) predicts clinical, electrophysiologic (EP) findings and long-term outcome. We included in the study 121 consecutive patients seen in our EP laboratory with documented and inducible sustained VT/VF. Patients were categorized into three groups according to their clinical presentation: (1) cardiac arrest (CA)-53 patients; (2) syncope (S)-20 patients; (3) palpitations/dizziness (P)-48 patients. There were no significant differences in age, sex, or prevalence of underlying heart disease between groups. The left ventricular ejection fraction (LVEF) was significantly lower for patients with CA (mean +/- S.D.; 31 +/- 14%) or S (30 +/- 11%) when compared with P (39 +/- 15%) (p less than 0.05). Induction of VT/VF required a more aggressive stimulation protocol (three extrastimuli) in patients with CA (53%) when compared with patients with S (30%) or P (29%) (p less than 0.05). The cycle length of the induced VT was shorter for CA (239 +/- 64 msec) patients as compared with the S (294 +/- 67 msec) or the P (319 +/- 94 msec) patients (p less than 0.01). Polymorphic VT or VF was induced in 28% of CA patients, in 9% of S patients, and in 12% of P patients (p less than 0.05). There were significantly more sudden deaths observed during the 4-year follow-up interval in patients presenting with CA compared to the P group (p less than 0.05). The 4-year survival was 67 +/- 8% for P, 45 +/- 15% for S, and 45 +/- 10% for CA patients (N.S.).(ABSTRACT TRUNCATED AT 250 WORDS)

The ESVEM trial. Electrophysiologic Study Versus Electrocardiographic Monitoring for selection of antiarrhythmic therapy of ventricular tachyarrhythmias. The ESVEM Investigators

ESVEM (Electrophysiologic Study Versus Electrocardiographic Monitoring) is an ongoing multicenter trial supported by the National Heart, Lung, and Blood Institute that began enrollment of patients on October 1, 1985. We describe here the methodology of the trial and data regarding enrollment of patients in the trial. The purpose of the trial is to determine whether electrophysiologic study or electrocardiographic Holter monitoring more accurately predicts antiarrhythmic drug efficacy in patients with aborted sudden death or sustained ventricular tachyarrhythmias. Consenting patients with inducible, sustained ventricular tachyarrhythmias and at least 480 premature ventricular contractions during 48 hours are randomized to undergo antiarrhythmic drug selection either by electrophysiologic study or by Holter monitoring. Up to six drugs (mexiletine, pirmenol, procainamide, propafenone, quinidine, and sotalol) are assessed in random order until one is predicted effective. An efficacy prediction is achieved in the electrophysiology limb if ventricular tachyarrhythmias are no longer inducible and in the Holter limb if ventricular ectopy is largely suppressed. Patients in whom a drug is predicted effective are followed while they are taking that drug to detect one of the three primary endpoints: arrhythmia recurrence, sudden death, or unmonitored syncope. In the first 37 months, 967 patients satisfied inclusion and exclusion criteria to undergo baseline studies. Two hundred eighty-six were eligible for and consented to randomization. In total, approximately 500 patients will be randomized and 285 subjects will be followed while receiving drugs that are predicted effective in this trial. Approximately 70 patients are expected to attain a primary end-point during a mean follow-up ot 3 years.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Predictive value of various types of ventricular response to programmed ventricular stimulation: relation to Holter monitoring

The study was performed to determine the predictive value of programmed stimulation for identification of pts with ventricular arrhythmias: 75 patients were studied by means of 24-hour ambulatory ECG (24 ECG) and programmed right (in some patients also left) ventricle stimulation at sinus and two or three pacing rates using two (standard) and three extrastimuli or burst stimulation (extensive protocol). Lown classes 0, 1-3 and 4a-4b were observed in 24 ECG in 35, 14, and 26 patients, respectively. In programmed stimulation 1-6 repetitive ventricular responses (RVR) were found in 56 pts, nonsustained ventricular tachycardia in 11 and sustained ventricular tachycardia in 21 pts. High incidence of induced VT was found in pts with complex ventricular arrhythmia in 24 ECG, 81% of this group, in all but six pts only standard protocol was used. The 1-6 RVR were observed in almost 40% of pts without any arrhythmia.

CONCLUSION

Only VT induction is a useful index for high risk patients.

Significant variability in the mode of ventricular tachycardia induction and its implications for interpretation of acute drug testing

Fifty-four patients with previous myocardial infarction and sustained ventricular tachycardia on fibrillation underwent two electrophysiologic studies in the drug-free state within 72 hours. Although the concordance of overall ventricular tachycardia induction over the 2 days was good (87% of patients), there was variability in the number of extrastimuli needed to induce sustained ventricular tachycardia on each day in 60% of patients. Of those in whom ventricular tachycardia was inducible on both days, 40% required additional extrastimuli and 20% required fewer extrastimuli. A change by two or more extrastimuli was found in 12% of patients. There was no correlation between the variability observed and multiple clinical and laboratory parameters (including the aggressiveness of the stimulation protocol); however, the direction of the variability (easier or harder to induce) correlated with changes in ventricular refractoriness. Inherent day-to-day variability may affect the reproducibility of electrophysiologic studies and influence the results of serial drug testing.

A randomized clinical trial of the noninvasive and invasive approaches to drug therapy of ventricular tachycardia

There is controversy over whether therapy to prevent ventricular tachyarrhythmias should be selected noninvasively (by trying drugs and monitoring the patient electrocardiographically) or invasively (by selecting a drug that prevents induction of the arrhythmia by programmed stimulation). We randomly assigned 57 patients with symptomatic and demonstrable ventricular tachyarrhythmias to therapy selected either noninvasively or invasively. The tachyarrhythmias involved were sustained ventricular tachycardia (35 patients), nonsustained ventricular tachycardia with hypotension (15 patients), and ventricular fibrillation (7 patients). The noninvasive approach sought reduction of ventricular premature beats by more than 80 percent and of couplets by more than 90 percent, with elimination of three or more successive ventricular beats on ambulatory monitoring and exercise testing. The invasive approach sought to prevent the induction of five or more repetitive beats by programmed stimulation. The noninvasive approach required fewer drug trials (3.2 +/- 1.8 [mean +/- SD] vs. 5.5 +/- 2.8, P less than 0.001) and fewer hospital days (20 +/- 15 vs. 33 +/- 24, P = 0.01) and identified a therapy predicted to be effective for more patients than did the invasive approach (29 of 29 vs. 15 of 28, P less than 0.001). When a predicted effective therapy was not found, amiodarone was prescribed despite persisting inducibility of ventricular tachycardia. Patients randomly assigned to the noninvasive approach had more symptomatic recurrences of tachyarrhythmia than those treated by the invasive approach (two-year actuarial probabilities of 0.50 +/- 0.10 vs. 0.20 +/- 0.08, P = 0.02). Similar differences were observed when amiodarone recipients were excluded. There were only three deaths from recurrent ventricular tachyarrhythmias--two in the group whose treatment was selected noninvasively and one in the group whose treatment was selected invasively (not significant). We conclude that therapy selected by the invasive approach prevents recurrences of ventricular tachyarrhythmias better than that selected by the noninvasive approach.

Spontaneous arrhythmia detected on ambulatory electrocardiographic recording lacks precision in predicting inducibility of ventricular tachycardia during electrophysiologic study

This study investigates the relation of spontaneous ventricular arrhythmia on ambulatory electrocardiographic (ECG) monitoring to the subsequent inducibility of ventricular tachycardia during programmed electrical stimulation. Eighty patients (65 men, 15 women), whose mean age was 58 years, presented with one of the following: sustained ventricular tachycardia (n = 54); sudden death requiring resuscitation (n = 4); ventricular fibrillation (n = 11); or syncope thought to be of cardiac origin (n = 11). All patients had 24 hour ambulatory electrocardiograms and programmed electrical stimulation while receiving no antiarrhythmic therapy. Programmed electrical stimulation resulted in inducible sustained ventricular tachycardia (defined as a rate of greater than or equal to 120 beats/min for greater than or equal to 1 minute or requiring intervention) in 53 of the 80 patients. There was no measure of frequency or complexity of spontaneous arrhythmia detected on ambulatory ECG that could identify the degree of subsequent ventricular tachycardia inducibility during programmed electrical stimulation. In fact, 25% of patients who had inducible sustained ventricular tachycardia had little or no spontaneous arrhythmia on ambulatory ECG. Furthermore, of the 53 patients with inducible sustained ventricular tachycardia, 28 and 55% had no couplets or nonsustained ventricular tachycardia, respectively, during ambulatory monitoring. The combination of a clinical presentation of sustained ventricular tachycardia, confirmed coronary artery disease and a left ventricular ejection fraction of less than 30% had a better positive predictive value than did any ambulatory ECG criterion in predicting the inducibility of sustained ventricular tachycardia.

Prevalence of late potentials in patients undergoing Holter monitoring

High-frequency, low-amplitude signals detected in the terminal portion of the surface QRS, called late potentials (LP), have been shown to correlate with inducible sustained ventricular tachycardia and to be absent in normal subjects. We studied LP in 152 patients without a history of sustained ventricular tachycardia who underwent 24-hour Holter monitoring for varying clinical indications (chest pain 21%, syncope 17%, palpitations 32%, dizziness 20%, other 10%). Twenty-one patients (14%) had a positive test. Of the 152 patients, 84 (55%) had complex ventricular arrhythmias and 68 (45%) had simple or no ventricular arrhythmias. Complex ventricular arrhythmias were present in 71% of patients with and in 52% of those without LP.

IN CONCLUSION

patients without history of sustained ventricular tachycardia who demonstrate complex nonsustained ventricular arrhythmias on Holter monitoring have a low prevalence of LP; the presence of LP on signal-averaged ECG indicates an electrical property of the heart, which is distinct from complex ventricular arrhythmias detected on Holter monitoring.

Effect of programmed ventricular stimulation on myocardial lactate extraction in patients with and without coronary artery disease

The arterial-coronary sinus lactate difference was measured in 17 patients after each step of a programmed ventricular stimulation protocol consisting of single, double, and triple extrastimuli, first at a basic drive cycle length of 600 msec, then at 400 msec, with an inter-train interval of 4 seconds. Four patients had no structural heart disease, four had an idiopathic dilated cardiomyopathy, and nine had coronary artery disease with a significant stenosis in at least one branch of the left coronary artery. Net myocardial lactate production during programmed ventricular stimulation was observed in three patients with coronary artery disease, but not in any patient without coronary artery disease. Among the patients who had coronary artery disease, net myocardial lactate production generally occurred in the patients who had more severe coronary artery disease. Exercise-induced ischemia, as demonstrated by a stress thallium-201 test, did not correlate with myocardial lactate production during programmed ventricular stimulation. Programmed ventricular stimulation, with a stimulation protocol typically used in many electrophysiology laboratories, is capable of inducing myocardial ischemia in at least some patients who have coronary artery disease. This finding suggests that myocardial ischemia may potentially influence the results of programmed ventricular stimulation in some patients with coronary artery disease.

Prospective comparison of Holter monitoring and electrophysiologic study in patients with coronary artery disease and sustained ventricular tachyarrhythmias

Baseline 24-hour Holter monitoring (HM) and electrophysiologic study (EPS) were compared in 43 consecutive patients with coronary artery disease who had sustained ventricular tachyarrhythmias to determine the fraction of patients in whom each could be performed and the fraction in whom each could be used to guide therapy. Patients were excluded from HM if sustained ventricular tachycardia (VT) requiring termination occurred and from EPS if heart failure was sufficiently severe to cause excessive risk. More patients completed EPS than HM (90% vs 71%), but this difference was not statistically significant (p = 0.12). Overall, HM detected arrhythmias suitable for antiarrhythmic drug assessment in 50% of patients: 30 or more ventricular premature complexes (VPCs) per hour in 50%, 10 or more VPC pairs in 44%, 5 or more runs in 19%, and 10 or more pairs and runs in 44%. Sustained monomorphic VT suitable for electropharmacologic testing was induced at EPS in 82% (p = 0.003 vs HM). Drug efficacy could be assessed in 70% of patients evaluated by HM, compared with 96% evaluated by EPS (p = 0.02). Thus, in consecutive coronary patients with sustained ventricular tachyarrhythmias, EPS could be used to guide therapy more frequently than HM.