Recurrent cardiac events in survivors of ventricular fibrillation or tachycardia. Implications for driving restrictions.

OBJECTIVE: To determine when survivors of ventricular tachycardia (VT) or ventricular fibrillation (VF) might most safely return to driving. DESIGN: Consecutive case series of 501 VT and VF survivors discharged alive between August 1978 and October 1989 and followed from 0 to 117 months (mean, 26 months). SETTING: Cardiac arrhythmia service of a university hospital. PATIENTS: The study group comprised 290 consecutive patients with sustained VT and 211 patients with VF who underwent electrophysiological studies and were discharged alive (78% male; mean age, 59 years). The mean ejection fraction (available in 338 patients) was 0.42. INTERVENTIONS: Antiarrhythmic drug testing for all patients was guided by serial electrophysiological testing. Overall, 227 patients (45%) were discharged on conventional antiarrhythmic agents, 115 (23%) on amiodarone, 39 (8%) received an implantable defibrillator, and 120 (24%) received no specific antiarrhythmic therapy. MAIN OUTCOME MEASURES: Main outcomes included any event that could hamper a patient's ability to operate a motor vehicle. Specifically, these events included recurrent VF, poorly tolerated, hemodynamically unstable VT, syncope, sudden cardiac death, and implantable defibrillator discharge. RESULTS: Event risks were assessed during the first year after hospital discharge because that is when most patients decide whether to begin driving again. The 1-year outcome event rate for all 501 patients was 17%. Three distinct periods of risk were identified. The monthly hazard rate was highest in the first month after hospital discharge (4.22% per month), intermediate in months 2 through 7 (1.81% per month), and lowest in months 8 through 12 (0.63% per month). The 191 patients for whom no successful conventional antiarrhythmic drug could be found during electrophysiological testing experienced a persistently high monthly event risk (1.6%) during months 8 through 12. CONCLUSIONS: All survivors of VT or VF should refrain from driving during the first month after hospital discharge when the hazard for events that could impair their ability to drive is greatest. Our data would support restricting driving for most patients until the eighth month after hospital discharge, when risk becomes lowest. Restriction might be lengthened in patients for whom electrophysiological testing finds no satisfactory conventional antiarrhythmic agent because their risk remains higher than average even after 7 months. Individualized recommendations should be allowed because the accident rate for patients who actually suffer sudden death is low.

Serial electropharmacologic studies in patients with ischemic heart disease and sustained ventricular tachyarrhythmias: when is drug testing sufficient?

Serial testing of antiarrhythmic drugs by programmed electrical stimulation can be costly in time, expense and risk. The purpose of this study was to evaluate the results of serial electropharmacologic tests for similarities that might obviate the need for protracted drug testing. Serial electropharmacologic testing was performed in 283 patients with coronary artery disease and clinical sustained ventricular tachycardia (VT) or fibrillation (VF). Drug tests were defined as concordant if sustained VT or VF could be consistently induced, or failed to be consistently induced during all such trials in a given patient. The following drugs were included for testing: procainamide, quinidine and disopyramide (class IA); phenytoin, mexiletine and tocainide (class IB); and flecainide and encainide (class IC). All patients were serially tested with > or = 2 (mean and median, 3) antiarrhythmic agents regardless of results from drug-free testing or initial acute drug testing. Overall, the results of serial drug trials directed by programmed stimulation were concordant in more than two thirds of patients. Concordance was comparably high whether patients were serially tested with drugs within the same antiarrhythmic class, or with drugs from differing classes, and was not related to patients' clinical or electrophysiologic characteristics. Protracted serial electropharmacologic testing does not appear necessary for predicting successful or unsuccessful antiarrhythmic drug therapy in survivors of clinical VT or VF. Single drug testing can identify most patients whose arrhythmia will or will not respond to medications.

Analysis of local electrogram characteristics correlated with successful radiofrequency catheter ablation of accessory atrioventricular pathways.

UNLABELLED: Due to the limited myocardial lesions produced by radiofrequency current, the ablation of accessory pathways (AP) requires precise localization of such connections. The purpose of this study was to ascertain which characteristic(s) of the local bipolar electrogram, recorded from the ablation and adjacent electrode immediately prior to the application of radiofrequency current, correlated with precision in localization adequate to permit AP ablation. Signal analysis was performed for 326 sets of electrograms preceding the attempted ablation of 107 APs in 100 consecutive patients. For 80 antegrade APs, the following variables were evaluated: (1) the presence or absence of an AP potential; (2) the local atrial-AP interval; (3) the local atrioventricular (AV) interval; and (4) the relationship between the onset of local ventricular depolarization and onset of delta wave of the surface electrocardiogram. For the 27 concealed APs, the following characteristics were evaluated: (1) the presence or absence of an AP potential; and (2) the local VA interval during reciprocating tachycardia or ventricular pacing. RESULTS: Antegrade APs: By statistical analysis, the best correlate of successful ablation of an antegrade AP was a local AV interval less than or equal to 40 msec (positive predictive value = 94%; 95% confidence intervals [CI] = 81%-100%). Local AV intervals less than or equal to 50 msec preceded 88% of successful AP ablations, compared to only 8% of failed radiofrequency current applications. The positive predictive value of the other variables were: presence of an AP potential: 35% (95% CI = 27%-40%); local atrial-AP intervals less than or equal to 40 msec: 54% (95% CI = 43%-66%); and local ventricular depolarization preceding onset of the delta wave 43% (95% CI = 34%-52%). For concealed APs, the positive predictive value of a VA interval less than 60 msec was 71% (95% CI = 48%-88%); the positive predictive value for the presence of an AP potential was 58% (95% CI = 32%-81%). CONCLUSIONS: No single electrogram characteristic had a positive predictive value and a sensitivity greater than 90% for AP localization adequate for radiofrequency current ablation. For antegrade APs, the best correlate of adequate localization was a local AV interval less than or equal to 40 msec; as a corollary, radiofrequency current applications at sites where the local AV was greater than 60 msec, were unlikely to be effective. Objective criteria for the localization of concealed APs were less certain. Electrogram analysis, as a guide to AP localization and ablation, requires careful analysis of multiple variables, with analysis of the local AV interval a salient objective factor.

Day-to-day reproducibility of antiarrhythmic drug trials using programmed extrastimulus techniques for ventricular tachyarrhythmias associated with coronary artery disease.

Forty-nine patients with coronary artery disease and documented clinical sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) were studied twice in the drug-free state and twice during treatment with an identical antiarrhythmic medication at therapeutic plasma concentrations using an identical programmed electrical stimulation protocol. Tested drugs included procainamide, quinidine, disopyramide and phenytoin. During their 2 paired tests, 11 patients had nearly identical therapeutic plasma concentrations of antiarrhythmic agents (group I) and 38 patients had therapeutic plasma concentrations, but with more variation in drug levels between otherwise identical paired drug tests (group II). Overall, 71% of patients had inducible sustained VT or VF during drug testing. Induced ventricular arrhythmias were not reproducible in 45% of group I patients, despite restudy at nearly identical therapeutic plasma concentrations of an identical antiarrhythmic agent. Induced arrhythmias were also not reproducible in 16% of group II patients. This variability could not be attributed to the electrophysiologic characteristics of the patients studied. Drug trials directed by programmed stimulation should be cautiously interpreted because time-associated changes can mimic a change attributed to a beneficial or deleterious drug effect.

Assessment and follow-up of pediatric survivors of sudden cardiac death.

In the young patient resuscitated from sudden cardiac arrest, the risks of recurrence are uncertain and so are the criteria defining therapeutic efficacy for the presumed cause of the initial event. In this study, we analyzed the outcome of 15 consecutive young patients, who were resuscitated from pulseless ventricular tachycardia or ventricular fibrillation and who were evaluated by comprehensive hemodynamic and electrophysiological testing. Patients were 11.2 +/- 2.7 (mean +/- SD) years old at the time of their event, and each was known to have some form of heart disease before sudden cardiac arrest. Ventricular tachycardia or fibrillation was inducible by programmed electrical stimulation in eight patients. Accessory atrioventricular connections, with antegrade effective refractory periods less than 220 msec, were identified in three patients. Sustained atrial flutter was the only arrhythmia inducible in two patients, and no arrhythmias were inducible in two other patients. Surgical or electrophysiological-guided medical therapy resulted in noninducibility of the ventricular arrhythmias in six patients. Surgical division of the accessory atrioventricular connections was performed in three patients, and arrhythmias were not inducible after operation. The four patients with atrial flutter or without defined arrhythmia were treated with an empiric therapy. During 37 +/- 14 months of follow-up, the nine patients with documented noninducibility of a defined cause of sudden cardiac arrest were free of recurrent events. In contrast, during 18 +/- 10 months of follow-up, two of the six patients with empiric therapy or persistent inducibility of ventricular tachycardia died suddenly, and three others had recurrence of ventricular tachycardia or fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular fibrillation survivors in whom tachyarrhythmia cannot be induced: outcome related to selected therapy.

Eight-five patients were studied to determine the prognosis of the ventricular tachyarrhythmias at the time of electrophysiologic study. Twenty-five patients (29%) were not inducible when we used a stimulation protocol consisting of up to four extrastimuli delivered at two right ventricular sites. Patients with no inducible arrhythmias were younger (53 vs 59 yrs; p = .06) and had higher ejection fractions (.49 vs .34; p less than .04) than the inducible ventricular fibrillation survivors. Sex, cardiac diagnosis, time from event to electrophysiologic study, and antiarrhythmic therapy at the time of event did not discriminate between those with and those without inducible ventricular tachyarrhythmias. Survival free of recurrent sudden death or ventricular tachycardia was .86 +/- .05 and .95 +/- .05 for patients with and without inducible tachyarrhythmias, respectively (p = .22). Nine of 25 (36%) patients with no inducible arrhythmias developed inducible ventricular tachyarrhythmias when testing was repeated with an antiarrhythmic drug. Ventricular fibrillation survivors not inducible at the time of programmed ventricular stimulation (using a stimulation protocol consisting of four extrastimuli delivered at two right ventricular sites) seem to have a good prognosis. Many "noninducible" patients develop inducible tachyarrhythmias when placed on antiarrhythmic therapy. Because it is possible that these drugs are proarrhythmic, empiric antiarrhythmic therapy should be avoided in these patients.

Reproducibility of arrhythmia induction with intracardiac electrophysiologic testing: patients with clinical sustained ventricular tachyarrhythmias.

In order to characterize the day to day reproducibility of arrhythmias provoked during electrophysiologic stimulation, 114 patients with documented sustained clinical ventricular tachyarrhythmias were studied. Two baseline electrophysiologic tests were performed in the drug-free state and within 6 to 24 hours of one another. There was a significant increment (p less than or equal to 0.02) in the induction of sustained ventricular tachyarrhythmias as the number of programmed extrastimuli increased from one (10% induction) to four (64% induction). Provoked arrhythmias were observed to be more frequently nonreproducible (as reflected in a major change in rate or duration, or both, of an induced ventricular arrhythmia between baseline tests) as the number of extrastimuli increased from one (7%) to four (27%). Nonreproducibility with three and four extrastimuli was not significantly greater than when two extrastimuli were utilized. Electrophysiology-directed drug trials should be interpreted in light of this observed variability in induced arrhythmias.