M. J. E. Davis

The Australian intervention randomized control of rate in atrial fibrillation trial (AIRCRAFT)

OBJECTIVESnThe Australian Intervention Randomized Control of Rate in Atrial Fibrillation Trial was a multicenter trial of atrioventricular junction ablation and pacing (AVJAP) compared with pharmacologic ventricular rate control (medication [MED]) in patients with mild to moderately symptomatic permanent atrial fibrillation (AF).nnnBACKGROUNDnThere have been very few prospective randomized trials, undertaken in highly symptomatic patients, comparing AVJAP with pharmacologic methods of ventricular rate control for patients with permanent AF.nnnMETHODSnThere were 99 patients (70 men, mean age 68 +/- 8.6 years) at five centers. Forty-nine patients were randomized to AVJAP while 50 patients were randomized to pharmacologic control. The primary end point was cardiac function measured by echocardiography and exercise tolerance. The secondary end points were ventricular rate control, evaluated by 24-h ambulatory electrocardiographic monitoring, and quality of life. Data were collected at randomization and then at one month, six months, and 12 months post-randomization.nnnRESULTSnAt 12 months follow-up there was no significant difference in left ventricular ejection fraction (AVJAP: 54 +/- 17%; MED: 61 +/- 13% [p = ns]) or exercise duration on treadmill testing (AVJAP: 4.1 +/- 2 min; MED: 4.6 +/- 2 min [p = ns]); however, the peak ventricular rate was lower in the AVJAP group during exercise (112 +/- 17 beats/min vs. 153 +/- 36 beats/min, p < 0.05) and activities of daily life (117 +/- 16 beats/min vs. 152 +/- 37 beats/min, p < 0.05). The CAST quality-of-life questionnaire revealed that patients in the AVJAP group had fewer symptoms at six months (p = 0.003) and at 12 months (p = 0.004). The observed relative risk reduction in symptoms at 12 months was 18%. Global subjective semiquantitative measurement of quality of life using the ladder of life revealed that the AVJAP group reported a 6% better quality of life at six months (p = 0.011).nnnCONCLUSIONSnIn this trial, AVJAP for patients with mild to moderately symptomatic permanent AF did not worsen cardiac function during long-term follow-up, and quality of life was improved.

The Impact of the Implantable Cardioverter Defibrillator on Quality-of-Life

The implantable Cardioverter defibrillator (ICD) is an established treatment for patients with life‐threatening ventricular arrhythmias. While it clearly reduces the incidence of death from recurrent arrhythmia, little is known about the impact on patients quality‐of‐life. In this prospective study, quality‐of‐life was assessed by questionnaire before and after ICD implantation. The “Sickness Impact Profile” (SIP), which evaluates physical, psychosocial, and other activities, as well as functions of daily life, was used. Employment and rehospitalization rates were also examined. Twenty‐one of 23 consecutive patients, aged 58 ± 11 years, undergoing ICD implantation at Royal Perth Hospital were studied. During the 14 ± 8 month follow‐up, 4 patients died. Functional capacity was unchanged in all but one of the survivors in whom it improved from New York Heart Association Class III to II. Four of 8 survivors employed before implant have since retired. Six patients required rehospitalization on 13 occasions, problems related to arrhythmias or the ICD. Overall SIP scores preimplant (11.2 ± 9.3; P < 0.05) were significantly worse at 6‐month follow‐up (21.7 ± 18.2), but returned to preimplant levels by 12‐month follow‐up (8.8 ± 10.8; NS). This was primarily due to transient problems in the areas of emotional behavior, alertness, and social interaction. SIP psychosocial dimension scores: preimplant: 7.2 ± 9.0; 6‐month: 17.8 ± 18.1 (P < 0.05); and 12‐month: 8.6 ± 10.3 (NS). Early retirement and hospitalizations due to arrhythmias may still be expected even after implantation of an ICD; however, quality‐of‐life appears only to temporarily decline.

Effect of early anticoagulation on the frequency of left ventricular thrombi after anterior wall acute myocardial infarction

To determine the effect of early anticoagulation on the incidence of left ventricular thrombi complicating anterior acute myocardial infarction (AMI), 82 consecutive patients admitted within 12 hours of symptom onset and with electrocardiographic changes consistent with anterior AMI were randomly assigned to 1 of 2 treatment groups. Group 1 patients received high-dose intravenous heparin to maintain the whole blood clotting time between 15 and 20 minutes, and commenced warfarin therapy within 48 hours. Group 2 patients received low-dose subcutaneous heparin and warfarin therapy if the peak creatine kinase level was more than 1,000 U/liter. Eighteen group 2 patients received warfarin, but none had a therapeutic prothrombin ratio within 5 days. The presence and morphologic characteristics of thrombus were assessed by serial 2-dimensional echocardiography. Thirty patients were excluded because AMI was not confirmed or because of technically unsatisfactory echocardiograms, death, surgery or, in group 1 patients, inadequate anticoagulation. Thrombi were identified in 29 of 52 patients (56%): in 14 of 25 group 1 patients (56%) and 15 of 27 group 2 patients (56%). Twenty-three thrombi formed within 3 days. Thrombi were protruding rather than mural only in 3 group 2 patients. The groups did not differ in baseline characteristics or in incidence, time of appearance or morphologic characteristics of thrombus (p greater than 0.05, beta for more than 25% reduction in incidence with group 1 treatment less than 0.10). Systemic embolism occurred only in 1 group 2 patient with mural thrombus.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiofrequency Catheter Ablation of Refractory Ventricular Tachycardia

Transcatheter radiofrequency ablation of the arrhythmia focus was attempted in a 68‐year‐old patient with recurrent ventricular tachycardia, both spontaneous and inducible by programmed ventricular stimulation despite treatment with multiple antiarrhythmic drugs. The procedure was performed under local anesthetic without complication. The arrhythmia was not inducible immediately following ablation or 5 days later, and during 5 months follow‐up there has been no spontaneous recurrence.

Undesirable Mode Switching with a Dual Chamher Rate Responsive Pacemaker

The Telectronics 1250 Meta MV DDDR pacemaker is a new device featuring automatic mode switching from DDDH to VVIR pacing in the event of an atrial arrhythmia. Although mode switching is a valuable feature, sinus tachycardia can cause an undesirable mode switch to occur. Of 24 implants at this institution, 11 have been for an AV conduction disorder. Eight of these 11 patients were specificalJy evaiuated for undesirable mode switching. During exercise testing and/or Holter monitoring, mode switching was repeatediy seen in seven of the eight at low levels of exercise. Factors precipitating mode switching were a low rate response factor, low upper rate setting, long base postventricular atrial refractory period (PVARP) and a long AV delay. During Holter monitoring, patients spent up to 50% of the time in VVIR pacing as opposed to DDDR pacing. It is concluded that patients with intact sinus node function are at risk of undesirable mode switching and should probably be programmed to the DDD mode unless there is a specific indication for DDDR pacing. If the DDDR mode is chosen, careful selection of the aforementioned pacing parameters is required.

Predictors of early and late recurrence of atrioventricular accessory pathway conduction after apparently successful radiofrequency catheter ablation

The correlation between electrophysiologic parameters and recurrence in 239 patients who underwent successful catheter ablation for an accessory pathway mediated tachycardia was analysed. Pathway conduction recurred in 15 patients (6.3%) after a mean follow-up of 7.3 months. Recurrence was most common in patients with right free wall pathways (17.1%). Accessory pathway conduction resumed in 18.9% of patients with decremental ventriculo-atrial (VA) conduction post-ablation compared with those patients without VA conduction (3.4%) (P < 0.001). Recurrence was common also in patients with repeated return of accessory pathway conduction during the ablation procedure (40% vs. 1.3%, P < 0.01). The patients in whom these observations are made should be monitored closely for recurrence of accessory pathway conduction post-ablation.

Radiofrequency catheter ablation of the AV node to improve the function of an antitachycardia implantable defibrillator.

A case of coexisting atrial fibrillation and ventricular tachycardia in a patient with an implantable cardioverter defibrillator is described. Despite careful reprogramming, the device was not always able to distinguish between the two arrhythmias and continued to deliver inappropriate antitachycardia therapy including DC shocks. Attempts to pharmacologically control the atrial fibrillation were unsuccessful so radiofrequency ablation of the atrioventricular node was performed. Following successful ablation, there have been no further false detections nor episodes of further ventricular tachycardia.

Catheter Ablation of Ventriculoatrial Conduction in the Treatment of Pacemaker-Mediated Tachycardia

Pacemaker generator reprogramming does not always present an adequate solution to the problem of pacemaker‐mediated tachycardia. A case is described where direct current shock catheter ablation of ventriculoatrial conduction prevented pacemaker‐mediated tachycardia and allowed optimal dual chamber pacemaker programming.

Echocardiographic diagnosis of cardiac embolus

We describe a case of thromboembolism to the right atrium, diagnosed echocardiographically. The thrombus subsequently embolised to the pulmonary arteries with survival of the patient.

Permanent pacing system malfunction due to hidden adjacent fractures of atrial and ventricular leads

Periods of failure of ventricular pacing and atrial sensing were discovered on Holter recording in a 10-year-old boy 4 years after the implantation of a dual-chamber pacemaker with endocardial bipolar leads brought out through the right atrial wall. The old generator was explanted and the old leads tested. There was considerable atrial oversensing of an electrical artefact. The pacing threshold of ventricular lead was 1.8 V compared with 0.3 V 6 days post implantation. Post-operative lateral chest X-ray disclosed fractures of both atrial and ventricular leads at the approximate site of exit from the right atriotomy. Review of the preoperative lateral film showed that the fractures had been hidden by an ECG electrode.