The proarrhythmic effects of antiarrhythmic drugs

Predictors of atrial flutter with 1:1 conduction in patients treated with class I antiarrhythmic drugs for atrial tachyarrhythmias

OBJECTIVES

The purpose of the study was to look for the predictor factors of atrial proarrhythmic effects of class I antiarrhythmic drugs.

BACKGROUND

Class I antiarrhythmic drugs may induce or exacerbate cardiac arrhythmias. The predictors of ventricular proarrhythmia are known. The predictors of atrial flutter with 1:1 conduction are unknown.

METHODS

Clinical history, EGG, signal-averaged EGG (SAECG) and electrophysiologic study were analysed in 24 cases of 1:1 atrial flutter with class I AA drugs and in 100 control patients without history of 1:1 atrial flutter with class I AA drugs.

RESULTS

The ages of patients varied from 46 to 78 years. Underlying heart disease was present in nine patients. The surface EGG revealed the presence of a short PR interval (PR<0.13 ms), visible in leads V5, V6 in eight (35%) patients with normal P wave duration; in other patients with prolonged P wave duration, PR seemed normaL On SAECG recording, there was a pseudofusion between P wave and QRS complex. The electrophysiologic study revealed some signs indicating a rapid AV nodal conduction (short AH interval or rate of 2nd degree AV block at atrial pacing >200 beats/mm) in 19 of the 23 studied patients. All patients, except one, had at least one sign indicating a rapid AV nodal conduction (short PR and/or P wave-QRS complex continuity on SAECG). In the control group, seven patients (7%) had a short PR interval (P<0.01) and 11 (11%) had a pseudofusion between P wave and QRS complex on SAECG (P<0.001). The P wave-QRS complex pseudofusion on SAECG had a sensitivity of 100% and a specificity of 89% for the prediction of an atrial proarrhythmic effect with class I antiarrhythmic drug.

CONCLUSION

We recommend avoiding class I AA drugs in patients with a short PR interval on surface EGG and to record SAECG in those with apparently normal PR interval to detect a continuity between P wave and QRS complex, which could indicate a rapid AV nodal conduction, predisposing to 1:1 atrial flutter with the drug.

Catheter ablation in supraventricular tachycardia

The evolution of catheter ablation for the treatment of supraventricular tachycardias represents a major advance in the management of cardiac arrhythmias. Excellent results in the majority of patients undergoing the procedure, together with a low rate of early complications and a brief hospitalization, make catheter ablation a highly cost-effective permanent cure. At present, however, its place in relation to alternate therapies in the management of supraventricular tachycardias has not been clearly established owing to unresolved risk-benefit issues. Continuing technical advances will likely enable catheter ablation to be successfully applied to a broader range of cardiac arrhythmias.

Radiofrequency catheter ablation of accessory atrioventricular connections in 250 patients. Abbreviated therapeutic approach to Wolff-Parkinson-White syndrome

BACKGROUND

The purpose of this study was to report the results and complications of radiofrequency catheter ablation of accessory atrioventricular (AV) connections by using an abbreviated approach aimed at minimizing the duration of the procedure.

METHODS AND RESULTS

Two hundred fifty consecutive patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory AV connection underwent catheter ablation with the use of radiofrequency current. In 179 of the 250 patients, catheter ablation was performed at the time of an initial electrophysiology test. Two hundred thirty-five patients had one accessory AV connection and 15 patients had two or more. One hundred eighty-three accessory AV connections were manifest and 84 were concealed. One hundred sixty-one were were located in the free wall of the left ventricle, 47 were in the right free wall, 44 were posteroseptal, 10 were anteroseptal, and five were intermediate test, and the ablation procedure was recorded for each patient, as was the total duration of fluoroscopy. A follow-up electrophysiology test was performed 2-3 months after the ablation procedure. Ninety-four percent of patients had all accessory AV connections successfully ablated and remained free of symptomatic tachycardia during a mean follow-up of 10 +/- 4 months. Two hundred nineteen patients (88%) had all accessory AV connections ablated during the initial attempt at catheter ablation. Mean duration of the entire procedure was 134 +/- 75 minutes. Procedure duration was longest in patients with multiple accessory AV connections, shortest in patients with intermediate septal accessory AV connections, and similar in all other locations. A nonfatal complication occurred in nine patients (4%).

CONCLUSIONS

The results of this study indicate that catheter ablation of accessory AV connections with radiofrequency current can be performed safely and expeditiously in a majority of patients and confirm in a large series the feasibility of catheter ablation at the time of an initial diagnostic electrophysiology test. This abbreviated therapeutic approach avoids the need for electropharmacological testing, long-term antiarrhythmic drug therapy, and surgical therapy in the majority of patients with the Wolff-Parkinson-White syndrome or with symptomatic tachycardias involving accessory AV connections.

Evaluation of bepridil efficacy by electrophysiologic testing in patients with recurrent ventricular tachycardia: comparison of two regimens

The purpose of the study was to evaluate this effect of different doses of intravenous and oral bepridil on the induction of ventricular tachycardia. Thirty-eight patients underwent electrophysiologic evaluation for recurrent ventricular tachycardia (VT). Sustained monomorphic VT was induced by programmed ventricular stimulation, using up to three extrastimuli in all patients. The effects of intravenous bepridil (2 mg/kg) were evaluated during the initial study. Intravenous bepridil prevented the induction of sustained VT in eight patients (21%). Electrophysiologic study was repeated after oral bepridil. In six patients the study was stopped because of adverse effects or VT recurrence. Thirty-two patients underwent repeat study 7 days later, taking oral bepridil, 500 mg/day (n = 16) or 900/day (n = 16). A dose of 500 mg/day of bepridil prevented the induction of sustained VT in only one patient. A dose of 900 mg/day of bepridil prevented the induction of sustained VT in eight patients. There were no significant clinical adverse effects, except in one patient receiving intravenous bepridil. The response to intravenous bepridil did not predict the response to oral bepridil. The response to intravenous or oral bepridil was not related to the plasma level of bepridil but was related to a higher left ventricular ejection fraction. Eight patients (21%) in whom VTs were noninducible on oral bepridil were discharged on 300 mg/day of bepridil if their initial loading dose was 500 mg/day or on 600 mg/day if their initial loading dose was 900 mg/day. They remained free of VT during a follow-up of at least 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Provocation of supraventricular tachycardias by an intravenous class I antiarrhythmic drug

Antiarrhythmic drugs may aggravate or induce ventricular arrhythmia. The induction of a supraventricular tachycardia or its facilitation has rarely been reported. The purpose of the study was to know whether the potential for supraventricular proarrhythmic effect of a class Ia intravenous antiarrhythmic drug can be exposed during electrophysiologic study. Ajmaline was chosen because of its short duration of action. The protocol of the study consisted of an electrophysiological study and programmed atrial stimulation using 1 and 2 extrastimuli on driven rhythm and atrial pacing up to second-degree atrioventricular block. Then 1 mg/kg of ajmaline was injected and atrial pacing was performed 3 minutes after its injection. Supraventricular proarrhythmic effect of ajmaline was defined as the spontaneous occurrence of a supraventricular tachycardia or the facilitation of its induction. Seventy patients among 1955 presented a proarrhythmic effect: 63 developed a supraventricular tachyarrhythmia (atrial flutter, fibrillation, tachycardia) and 7 an atrioventricular reentrant tachycardia, either spontaneously (n = 23) or during atrial pacing (n = 47). Risk factors were identified in most patients: old age, underlying heart disease, history of spontaneous supraventricular tachycardia and/or induction of a supraventricular tachycardia by 2 extrastimuli on driven rhythm in the control state (34 patients), sinus node dysfunction (22 patients). Compared with patients without proarrhythmic supraventricular effect only the history of spontaneous supraventricular tachycardia and the existence of a sinus node dysfunction were significantly more frequent (P less than 0.05) in patients with proarrhythmic effect of ajmaline. In conclusion, the supraventricular proarrhythmic effect of intravenous ajmaline exists and is related both to the electrophysiologic characteristics of the drug and to the arrhythmia substrate. The results indicate that a supraventricular tachyarrhythmia may be induced by a class I antiarrhythmic drug.

Direct current shock ablation: quantitative assessment of proarrhythmic effects

Catheter ablation using direct current (DC) shock has proved invaluable in the management of a variety of tachycardias. However, sporadic reports of fatal arrhythmias following ablation have raised the question of the proarrhythmic potential of DC shock ablation. The present study was undertaken in 45 patients to assess prospectively any proarrhythmia related to DC shock ablation, using matched pre- and postablation Holter monitors and programmed electrical stimulation (PES). Nineteen of these patients had Holter monitors for three successive postablation days to observe trends. There was unmatched data in 11 additional patients. All 56 patients provided prospective follow-up for clinical events. There was no immediate sustained VT/VF at the time of the ablation. Four patients had sustained VT in the first 72 hours after ablation; three episodes were similar to the preablation clinical arrhythmias; one patient had torsades de pointes interrupting bradycardia. Twelve patients met Holter, PES, or clinical criteria for proarrhythmia; none were treated on the basis of these findings. On Holter monitoring, there were significant increases in VPCs/hour and couplets/hour in patients undergoing atrial or atrioventricular junctional ablations; and an increase in couplets after accessory pathway ablations. Increases in these categories were not significant for VT patients; nor were increases in episodes of VT/hour or atrial arrhythmias significant in any group. Patients were followed for 44 +/- 33 months, with an actuarial survival of 95% at 1 year, 88% at 3 years, and 85% at 4 years. There were six deaths during follow-up. Two patients had sudden death: one at 2 months had early evidence of proarrhythmia; the other at 32 months may have represented later myocardia deterioration. One patient died of heart failure at 77 months; and there were three noncardiac deaths. DC shock ablation in humans is much less proarrhythmic than in dogs. The low incidence of clinical proarrhythmic events during prolonged follow-up after discharge resulted in low sensitivity, specificity, and positive predictive values for Holter and PES, although the negative predictive values of these tests were greater than 90%. Only one of 12 patients who met criteria for proarrhythmia in the days immediately following ablation had subsequent clinical events consistent with proarrhythmia. These results may be useful as standards for comparison with results of radiofrequency or other ablation modalities.

Radiation exposure during radiofrequency catheter ablation of accessory atrioventricular connections

BACKGROUND

Catheter ablation of accessory atrioventricular (AV) connections has been demonstrated to be effective in more than 85% of patients. One of the risks of this procedure is radiation exposure during the fluoroscopic imaging necessary to guide catheter manipulation. The objective of the present study was to measure the radiation received by patients and physicians during radiofrequency catheter ablation and to estimate the resultant somatic and genetic risks.

METHODS AND RESULTS

Radiation exposure to patients and physicians was measured during attempts at radiofrequency catheter ablation of accessory AV connections in 31 consecutive patients. Radiation exposure was measured using thermoluminescent sensors placed on the patient and on the physician. Somatic and genetic risks were estimated based on the radiation levels recorded using these sensors. The durations of fluoroscopy and of the catheter ablation procedure were recorded for each patient. Catheter ablation was successful in 28 of 31 patients (90%). Mean +/- SD duration of fluoroscopy was 44 +/- 40 minutes. The largest patient radiation dose was measured over the ninth vertebral body posteriorly (median, 7.26 rem [roentgen equivalents man]; range, 0.31-135.7 rem). Median radiation dose to the thyroid was 0.46 rem (range, 0.06-7.26 rem), and median radiation dose to the posterior iliac crest was 2.43 rem (range, 0.01-8.3 rem). The greatest radiation dose to the operator was recorded at the left hand (99 mrem). Mean radiation dose to the operator's eyes was 28 mrem.

CONCLUSIONS

Radiofrequency catheter ablation of accessory AV connections may result in significant radiation exposure to the patient and to the physician. Each hour of fluoroscopic imaging is associated with a lifetime risk of developing a fatal malignancy of 0.1% and a risk of a genetic defect of 20 per 1 million births. Although these risks must be recognized, they are relatively small compared with the risks associated with alternate approaches to management, including no therapy, antiarrhythmic drug therapy, and surgery.

Malignant ventricular tachycardia during propafenone treatment in a child with junctional automatic tachycardia: effectiveness of intravenous molar sodium lactate

Propafenone may aggravate the preexisting arrhythmia or induce another one. Usually, such proarrhythmic effects occur in patients with spontaneous ventricular arrhythmias and/or coronary heart disease with poor left ventricular function. We report the case of a 5-year-old girl with junctional automatic tachycardia and no structural heart disease, in whom malignant ventricular tachycardia occurring during propafenone treatment could be terminated by molar sodium lactate (MSL) infusion. The serum propafenone level obtained before MSL infusion was within the therapeutic range. Two hypothesis could explain the beneficial effects of MSL in our patient: (1) alkalinization facilitates the cell membrane hyperpolarization and thus can decrease the voltage-dependent effect of Class Ic drugs, (2) alkalinization could displace propafenone from its tissue receptor sites by an increase in the nonionized fraction.

Reproducibility in circadian rhythm of ventricular premature complexes

To evaluate the existence and reproducibility of a circadian rhythm of ventricular premature complexes (VPCs), 38 patients (mean age 57 +/- 17 years) with greater than or equal to VPCs/hour were studied with 24-hour electrocardiogram Holter monitoring. Nineteen patients had coronary artery disease and 19 had structurally normal hearts. A second Holter electrocardiogram was recorded in all patients from 2 to 47 days (mean 11) after the first. Chronobiologic analysis was made by single and mean cosinor methods. A significant and similar circadian rhythm of VPCs was found in the total sample both on the first (mesor 399, acrophase at 15:08, p less than 0.01) and the second day (mesor 306, acrophase at 14:47, p less than 0.05), with 2 main peaks, the first in the late morning and the second in the afternoon. However, only 18 patients (47%, group A) had a significant individual circadian rhythm of VPCs on both days, whereas 20 (53%, group B) did not have a significant rhythm in greater than or equal to 1 day. A high reproducibility of the circadian rhythm of VPCs was found in group A patients, with a difference of 2.1 +/- 1.8 hours between the acrophases of the 2 days, whereas the difference was 4.4 +/- 3.3 hours in group B patients (p less than 0.01). Among group A patients, 14 (78%) had a VPC rhythm with acrophase occurring during waking hours, whereas the acrophase of 4 (22%) occurred during the night. The reproducibility of the circadian rhythm of VPCs was not influenced by gender, presence of coronary disease, medical therapy, basal VPC number, or day-to-day variability of VPCs, although group A patients were older than group B patients (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical experience with sotalol in patients with drug-refractory ventricular arrhythmias

Sixty-five patients with symptomatic, drug-refractory, sustained ventricular tachycardia or fibrillation were treated with oral sotalol (80 to 480 mg twice daily). Sotalol was withdrawn in 11 patients because of continued inducibility of ventricular tachycardia at the time of follow-up electrophysiologic study. Therefore, the clinical effectiveness of sotalol could be evaluated in 54 patients followed up for 11.5 +/- 6 months (range 0.2 to 25). The actuarial incidence of successful sotalol therapy was 54 +/- 13% at 6 months and 47 +/- 13% at 12 months. In 39 patients who underwent electrophysiologic testing while receiving oral sotalol, the drug prevented the reinduction of ventricular tachycardia/fibrillation in 8 (20%). During follow-up study, arrhythmia recurred in 1 (17%) of 6 patients whose ventricular tachycardia was noninducible with oral sotalol and in 8 (44%) of 18 with inducible tachycardia but who were continued on oral sotalol therapy. Adverse effects were noted in 28 patients (42%), requiring drug withdrawal in 13 (22%) and dose reduction after hospital discharge in 10 (15%). Exacerbation of ventricular arrhythmia occurred in six patients (9%), one of whom had associated hypokalemia. Sotalol is frequently useful in the control of intractable, life-threatening ventricular arrhythmias, and its efficacy appears to be predicted by programmed stimulation. However, there is a high rate of limiting side effects, which precludes its use in a large number of patients, and a substantial risk of arrhythmia exacerbation.

Electrophysiologic evaluation of antiarrhythmic therapy for ventricular tachyarrhythmias

The use of electrophysiologic studies has contributed significantly to our understanding of the mechanisms of ventricular tachyarrhythmias and enhanced our ability to assess objectively the efficacy of various therapeutic interventions in modifying or preventing their recurrence. The basis on which electrophysiologic testing techniques is founded is the ability reproducibility to initiate ventricular arrhythmias by programmed electrical stimulation in patients with a history of recurrent ventricular tachycardia or fibrillation. Ventricular tachycardia can be initiated by electrophysiologic studies in approximately 90% of patients with clinically documented recurrent, sustained ventricular tachycardia related to coronary artery disease and in 60% of patients with nonsustained ventricular tachycardia. Reports indicate that electrophysiologic testing is highly specific as well (99% for sustained monomorphic ventricular tachycardia). Studies in patients with recurrent ventricular tachycardia demonstrate that prevention by antiarrhythmic drugs of the ability to initiate tachycardias that were previously inducible by comparable stimulation techniques in the absence of therapy is highly predictive of freedom from recurrent episodes of spontaneous ventricular tachycardia and ventricular fibrillation. This end point can be achieved in 35 to 75% of patients. This wide range of success rates results from differences in the patient populations studied, as well as major differences in the programmed stimulation and antiarrhythmic drug protocols used among laboratories. The positive predictive value of this technique (defined as the percentage of patients in whom complete suppression of inducible ventricular tachycardia or ventricular fibrillation is achieved during electrophysiologic testing with antiarrhythmic drugs and in whom no spontaneous arrhythmia occurs at 1- to 2-year follow-up) ranges between 80 and 95%.