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Background The use of temporary mechanical circulatory support (tMCS) during arrhythmia is increasing, although available evidence for this indication is limited, with significant gaps of knowledge regarding appropriate timing, management and configuration. This systematic review sought to analyze the use of tMCS in patients with life-threatening arrhythmia. Methods A systematic literature search identified 2529 references published until September 2019. Adult and pediatric patients diagnosed with all kind of life-threatening arrhythmia were included. tMCS was primarily compared to conventional non-tMCS therapies. Primary outcome measure was in-hospital or 30-day mortality. Results 19 non-randomized studies were selected, including 2465 adult and 82 pediatric patients. Primary outcome in tMCS patients varied widely (4–62%) with differences based on the use of prophylactic tMCS (4–21%) or rescue tMCS (58–62%). A substantial mortality benefit was observed among high-risk patients, as identified with PAINESD risk score or suffering from electrical storm and treated with prophylactic tMCS. During ablation procedures, tMCS patients showed higher rates of induced ventricular tachycardias (VTs), ablated VTs, VT termination and non-inducibility after ablation. Extracorporeal membrane oxygenation (ECMO) was applied in pediatric cases as hemodynamic protection for aggressive antiarrhythmic medical treatment with >80% survival. Conclusions Prophylactic tMCS is associated with improved survival as compared to rescue or no-tMCS in patients with life-threatening arrhythmia, and may be considered in patients with high PAINESD risk score or suffering from electrical storm. ECMO can be advised as rescue and support therapy in pediatric cases requiring aggressive antiarrhythmic medical treatment.

Aim Cryoballoon is a widely used tool for ablation for atrial fibrillation (AF). There are several complications after cryoablation. This paper assesses the incidence rate and severity of hemoptysis after cryo ablation for AF. Methods For current systemic review and meta-analysis, literature has been reviewed from 2008 to 2019 focusing on the incidence of hemoptysis after cryoballoon ablation for atrial fibrillation catheter ablation in PubMed, Cochrane library and EMBASE databases. Results This meta-analysis included 3534 patients from 20 studies; of mean age 54.0 ± 10.9 years. All patients had cryoballoon ablation for paroxysmal or persistent AF refractory to treatment and follow up duration for 8.2 ± 5.9 months with mean procedure duration of 153.4± 65.4 minutes. The mean cryoablation duration was 869.4 ± 148 sec with mean temperature of -59.7 ± 5.1 °C and a total of 109 patients (3.08%) had hemoptysis which was mild in the majority of cases (76.1%), mild to moderate in 20.2% and severe in only 3.7%. Hemoptysis onset was at 29.0 ± 56.5 day with median of 7 days, range (2 hours to 210 days). In 11 studies hemoptysis occurred early in 51 patients (95% CI for I2 was 0.0% to 0.0, P =0.95, I2 was 0.0%), but in 9 studies, hemoptysis occurred late in 58 patients (95% CI for I2 was 0.0% to 0.0, P =0.96, I2 was 0.0%). Conclusions Mild hemoptysis is experienced by significant number of cryoballoon AF ablation patients and severe type in 3.5 % attributed to significantly lower temperature in inferior pulmonary veins and is more often associated with bigger cryoballoon.

Contains fulltext : 209368.pdf (Publisher’s version ) (Open Access) BACKGROUND: The second-generation cryoballoon significantly improves outcome of pulmonary vein isolation (PVI) but may cause more complications than the first generation. Currently, no consensus regarding optimal cryoballoon application time exists. The 123-study aimed to assess the minimal cryoballoon application duration necessary to achieve PVI (primary endpoint) and the effect of application duration on prevention of phrenic nerve injury (PNI). METHODS: Patients

AIMS: Headache has been reported to occur during cryoballoon ablation for atrial fibrillation (AF). No study has systematically analysed this phenomenon.METHODS AND RESULTS: Twenty consecutive patients with symptomatic AF underwent cryoballoon ablation without sedation. Headache was evaluated before, during, and after the first cryoapplication in every pulmonary vein (PV) using a visual representation of a head for location of the headache, a numerical rating scale (NRS) for measuring pain intensity and the short-form McGill pain questionnaire (MPQ) for qualitative analysis of pain. The order in which the PVs were ablated was randomized. Sixteen (80%) patients perceived mainly frontal headache during cryoablation. The overall NRS scores were significantly higher during (5.1 ± 1.7), compared with before (2.7 ± 1.4), and after (3.5 ± 2.2) a cryoapplication (P < 0.05). The NRS score was significantly higher during ablation of the first PV. The intensity of the perceived headache was not related to the temperature reached 150 s after initiation of a cryoapplication (P = 0.81). Of the MPQ, three sensory adjectives and one affective adjective averaged between scores 1 and 2, representing mild-to-moderate severity of pain.CONCLUSION: The majority of patients treated by balloon cryoablation experienced headache during a cryoapplication. There was no correlation between the temperature reached during a cryoballoon freeze and the intensity of the headache. Cryoballoon ablation of the first PV was significantly more painful than the remaining PVs.

Background— Advancement of ventricular activation by an atrial premature beat (APB) given during His bundle refractoriness followed by resetting of an antidromic tachycardia (AT) in patients with decrementally conducting accessory pathway (DAP) is a helpful maneuver to prove pathway existence and participation in the circuit. We aim to assess in a large cohort the role of APB during AT in patients with a DAP. Methods and Results— Thirty-three patients with a DAP having 34 AT were included in the study: 29 patients had an atriofascicular pathway, 1 had a long atrioventricular DAP, and 4 had a short atrioventricular fiber. APBs were delivered initially from the lateral right atrium, scanning diastole with a 10-ms decrement until AT termination or refractoriness. We observed 4 patterns of response after APB during AT: advancement of activation (29 cases), delay (2), advancement followed by delay (3), and termination (7). Eight patients required an earlier APB to advance or delay ventricular activation. These 8 patients had a shorter AT cycle length (median of 273 versus 315 ms; P =0.003) and had a shorter resetting zone (median coupling interval of 30 versus 50 ms; P =0.01). Conclusions— APB delivered during AT in patients with a DAP advanced and/or delayed ventricular activation in all patients. In 1 of 5 of cases the AT was terminated by a single APB. In approximately a quarter of the patients an earlier coupled APB was needed to reset AT. The high RA was an adequate stimulation site in all right-sided DAP.

Recognition of the presence and role of decremental fibers during wide QRS tachycardia requires carefully executed intracardiac studies.This study sought to determine the value of the atrioventricular (AV) conduction time during pre-excited tachycardia to differentiate a fast from a decrementally conducting accessory pathway (AP).Fifty-one patients with 56 pre-excited tachycardias were included in the study: Group I: 27 patients with 31 antidromic tachycardia (ADT) using an atriofascicular pathway, Group II: 2 patients with pre-excited tachycardia due to bystander AV conduction, Group III: 3 patients with ADT and a short AV Mahaim fiber, and Group IV: 19 patients with 21 ADT using a fast conducting right-sided AP. The AV interval was measured in the His bundle electrogram and related to the tachycardia cycle length (TCL) by making an AV/TCL index.An AV intervalor = 150 ms during pre-excited tachycardia yielded a 91% sensitivity, 90% specificity, positive predictive value of 94%, and negative predictive value of 83% for AV conduction over a decrementally conducting pathway, whereas aor =0.55 AV/TCL index yielded a sensitivity of 89%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 84%. In 3 of 4 patients with Mahaim fibers and a0.55 AV/TCL index, a prolonged ventriculoatrial (VA) conduction time was found.An AV intervalor =150 ms during pre-excited tachycardia is a fast and reliable method for detecting a decrementally conducting AP. Correcting the AV interval by the tachycardia cycle length improved specificity and positive predictive accuracy.

Objectives This study was designed to evaluate the long-term effect of segmental pulmonary vein (PV) cryoablation in patients with recent-onset paroxysmal atrial fibrillation (PAF). Background Patients with PAF have more triggers to initiate and less substrate to sustain atrial fibrillation (AF). Elimination of the potential initiators alone may be sufficient to abolish the arrhythmia. Methods Patients with PAF were prospectively recruited from July 2001 to July 2005. If the triggers for AF were identified, PV cryoisolation of the arrhythmogenic vein(s) was performed. Otherwise, all PVs were isolated. Results Seventy patients with minimal or no heart disease (54 men; age 40 ± 10 years) were enrolled. The duration of AF was 4 ± 1 year. The left ventricular ejection fraction and left atrial size were 59 ± 8% and 41 ± 5 mm, respectively. An arrhythmogenic PV was found in 10 patients (14%). Complications occurred in 3 patients (4%). No PV stenosis or esophageal injury was detected during a mean follow-up of 33 ± 15 months. Thirty-four patients (49%) achieved complete success (no AF and no antiarrhythmic drugs [AAD]); 15 patients (22%) had no recurrences with AAD; and 8 patients (11%), still with sporadic bursts of AF, improved >50% with AAD. Overall, 82% of the patients benefited from the procedure. Patients in whom the arrhythmogenic PV was identified and isolated had no recurrences. Conclusions Pulmonary vein cryoisolation is effective in 82% of patients with recent-onset PAF during a mean follow-up of 33 ± 15 (range 15 to 60) months. If the arrhythmogenic PV is identified and isolated, the long-term outcome is excellent, indicating no need to isolate all PVs.

Antidromic Tachycardia in Patients with an Atriofascicular Fiber. Background: The typical and most common tachycardia in patients with atriofascicular pathways is a macro reentrant tachycardia, with anterograde conduction over the decrementally conducting bypass tract and retrograde conduction over the right bundle branch-His-AV node axis resulting in a short V-right bundle branch and short V-H interval. Objectives: To report on changes in rate and QRS configuration when right bundle branch block (RBBB) develops spontaneously during antidromic tachycardia using an atriofascicular fiber. Methods: Three of 25 patients with an antidromic circus movement tachycardia using a right-sided atriofascicular pathway showed episodes of right bundle branch block (RBBB) during ventriculo-atrial conduction. Effect of retrograde RBBB on tachycardia rate and QRS configuration was studied using intracardiac and extracardiac recordings. Results: All 3 patients showed prolongation of their V-A interval when retrograde RBBB occurred during tachycardia, resulting in a longer tachycardia cycle length. The VA time increase ranged from 85 to 100 msec, with a mean 346 ± 5 msec. Two of the 3 patients also showed a change in QRS configuration due to a more leftward shift of the frontal plane QRS axis. Conclusion: Rate changes in antidromic tachycardia in patients with atriofascicular fibers can be based on a shift in VA conduction from one bundle branch to the other. This may be accompanied by changes in the frontal plane QRS axis because of a change in ventricular activation sequence.

There is debate concerning the distal insertion of Mahaim fibers. Some findings favor an atriofascicular fiber connected with the distal right bundle branch. Other findings favor a long atrioventricular (AV) structure inserting into the myocardium. A patient having a decrementally conducting accessory pathway is reported. Proximal and distal Mahaim potentials were recorded during sinus rhythm, atrial pacing, and antidromic tachycardia. Both proximal and distal M potentials always preceded the QRS complex during sinus rhythm and antidromic tachycardia earlier than the right bundle branch potential. During tachycardia, the distal M potential was recorded 6 ms before the retrograde right bundle potential. Other arguments consistent with an AV connection were a change in the QRS configuration during tachycardia after the first radiofrequency pulse at the site of the distal M potential and absence of right bundle branch block after successful ablation. Conduction through the proximal part of the Mahaim fiber was unaltered after ablation, as assessed by recording the proximal M potential. Electrophysiologic evidence is presented suggesting a long AV accessory pathway inserting close to the distal right bundle branch rather than an atriofascicular connection in this patient with a Mahaim fiber.

The aim of this study was to compare single-3-minute (single-3) with double-3-minute (double-3) cryothermia applications for treatment of atrial flutter (AFL).Previous animal studies have indicated the need for a double 5-minute cryothermal application to create large and permanent lesions.Forty patients (56 +/- 13 years old) with typical AFL (cycle length 229 +/- 35 ms) were randomized to single-3 (n = 20) or double-3 (n = 20) cryothermia applications at each site along the cavotricuspid isthmus (CTI). Cryoablation was performed with the CryoCor cryoablation system. A successful procedure was defined as noninducibility of AFL with the concomitant presence of bidirectional CTI conduction block under isoproterenol infusion.All but 1 patient (95%) of the single-3 group and all patients (100%) of the double-3 group were successfully ablated. The number of sites needed to create isthmus conduction block was 9 +/- 4 (single-3) and 8 +/- 2 (double-3) (NS). Fluoroscopy time did not differ between the two groups (single-3: 31 +/- 14; double-3: 36 +/- 17 min, NS). The procedure time of the single-3 group was significantly shorter compared to the procedure time of the double-3 group (mean procedure duration 132 +/- 64 vs 159 +/- 50 min, P.04). After a mean follow-up of 11.7 +/- 4.7 months, two recurrences of AFL occurred in the double-3 group.Single cryothermia applications of 3 minutes produce permanent CTI conduction block in patients with typical AFL and significantly reduce procedure duration.

Objectives The purpose of the study was to identify the electrocardiographic (ECG) characteristics of the Mahaim fiber. Background Mahaim fibers are slowly conducting accessory pathways reaching into the right ventricle. They often play a role in tachycardias. Methods We retrospectively analyzed 40 patients with Mahaim fibers. Five patients had associated Wolff-Parkinson-White syndrome and were excluded from the study. Two patients had a short atrioventricular decremental accessory pathwayand were also excluded. The remaining 33 patients had a tachycardia with anterograde conduction over a Mahaim fiber. Twenty were female. Their mean age was 24 ± 10 years. Results The most common pattern of minimal preexcitation during sinus rhythm was an rS pattern in lead III. This was found in 20 patients. There was a match between the presence of rS in lead III during sinus rhythm and left axis deviation during tachycardia with anterograde conduction over the Mahaim fiber. After ablation, a different QRS pattern emerged in lead III, indicating the absence of conduction over the Mahaim fiber. To obtain information on the prevalence of an rS pattern in lead III in age-matched controls with palpitations and without structural heart disease, the 12-lead ECG of 200 young individuals were examined. An rS pattern in lead III was found in 6%. Conclusions A narrow QRS with an rS pattern in lead III during sinus rhythm in a patient with a history of palpitations should alert the physician to the possibility of a Mahaim fiber. During tachycardia, these patients typically show a left bundle branch block-like QRS complex with left axis deviation.

Introduction: Automatic rhythms associated with Mahaim fibers usually occur during radiofrequency catheter ablation. The incidence and significance of spontaneous automaticity in Mahaim fibers are unknown. Methods and Results: Spontaneous automatic rhythms were observed in 5 (12.5%) of 40 patients with Mahaim fibers referred for nonpharmacologic therapy because of recurrent episodes of symptomatic tachyarrhythmias, usually antidromic circus movement tachycardia (33/40 patients). Three were female and two were male. Their mean age was 15 ± 7 years compared to 26 ± 13 years of the patients without automaticity (P = 0.09). Three patients had both antidromic tachycardia and asymptomatic spontaneous automatic rhythms recorded during ambulatory ECG (1 patient) or electrophysiologic study (2 patients). In 2 patients, the automatic rhythm triggered antidromic tachycardia. Two other patients had nonsustained repetitive episodes of wide QRS tachycardia due to automaticity arising in the Mahaim fiber, without antidromic tachycardia. All automatic rhythms were abolished by successful catheter ablation of the Mahaim fibers. Conclusion: Spontaneous automaticity occurred in 12.5% of our Mahaim patients and may trigger antidromic tachycardia. Spontaneous automaticity, which is not seen in rapidly conducting accessory pathways, is another argument for the presence of an AV nodal-like structure in Mahaim fibers. (J Cardiovasc Electrophysiol, Vol. 15, pp. 738-744, July 2004)

Background— Cryoablation (cryo) has a high success rate in the short-term treatment of atrial flutter (AFL), but evidence of long-term efficacy is lacking. The present study reports the long-term effect of cryo of the cavotricuspid isthmus (CTI) in patients with common AFL. Methods and Results— Thirty-five consecutive patients (28 men; mean age, 53 years) underwent cryo of the CTI. In 34 patients, the AFL had a counterclockwise rotation (cycle length, 242±43 ms). Eleven patients had structural heart disease. Cryo was performed with a 10F catheter with a 6-mm-tip electrode (CryoCor). Applications (3 to 5 minutes each) were delivered by use of a point-by-point technique to create the ablation line. The acute end point of the procedure was creation of bidirectional isthmus conduction block and noninducibility of AFL. A median of 14 applications (range, 4 to 30) at 10 sites (range, 4 to 19) was given along the CTI with a mean temperature of −80.0±5.0°C. Mean fluoroscopy and procedure times were 40±26 minutes and 3.2±1.3 hours, respectively. Of the 35 patients, 34 were acutely successfully ablated (97%). After a mean follow-up of 17.6±6.2 months (range, 9.6 to 26.1 months), 31 patients (89%) did not have recurrence of AFL. Three of the 4 patients with recurrence had a second successful procedure. One patient had transient ST elevation in the inferior leads during cryoapplication. Conclusions— Cryo produces permanent bidirectional isthmus conduction block of the CTI. Short- and long-term success rates are comparable to those for radiofrequency ablation.

Objectives This study investigated whether pain catastrophizing is associated with distress and perceived disability in patients with atrial fibrillation, whether pain catastrophizing predicts pain and fear during a medical procedure of atrial cardioversion, and whether pain catastrophizing influences the effects of an opioid analgesic during internal cardioversion. Methods A secondary analysis is performed upon data from a double-blind placebo-controlled trial during which the effect of intranasal butorphanol tartrate (INB) was evaluated in patients with atrial fibrillation using a step-up internal atrial cardioversion protocol. Before the procedure, patients completed measures of pain catastrophizing, mood, distress and perceived disability. After each shock, patients completed measures of pain and fear. Results We found that pain catastrophizing predicted the affective pain rating of the first shock, and the fear increase during subsequent shocks. There was no effect of INB. However, when controlling for the differences in pain catastrophizing, INB significantly reduced fear as compared to placebo. This suggests that the effects of INB during atrial cardioversion were overshadowed by the effects of pain catastrophizing. Conclusions It is recommended that in future atrial cardioversion trials, stratification based on pain catastrophizing be performed. Reducing catastrophizing thinking about pain through cognitive–behavioral techniques are likely to reduce levels of fear during internal atrial cardioversion and may increase the effectiveness of concomitant analgesics.

Percutaneous ablation is a well-established technique for treating cardiac arrhythmia by removing or isolating tissue at the site of the abnormal impulse formation. Various forms of energy for ablation procedures may be delivered via a catheter with fluoroscopic guidance. The procedures most commonly performed are radiofrequency ablation and cryotherapy. Atrial fibrillation, the most frequently occurring supraventricular tachyarrhythmia, may be initiated by ectopic beats that originate in the ostia of the pulmonary veins. The clinical efficacy of isolation (or focal ablation) of the pulmonary veins for treatment of atrial fibrillation has been well demonstrated. Pre- and postprocedural examinations with computed tomography (CT) or magnetic resonance (MR) imaging are frequently performed to depict the anatomy and to obtain baseline measurements of the pulmonary veins to enable early detection of complications from ablation. Venous stenosis or thrombosis and pulmonary hypertension may occur after radio-frequency ablation. Familiarity with the appearance of normal anatomic variants at CT and MR imaging and with the normal range of pulmonary vein diameters is essential for preoperative management and early detection of procedure-related complications.

Objectives We sought to evaluate the efficacy and safety of pulmonary vein (PV) isolation using transvenous cryoablation for the treatment of atrial fibrillation (AF). Background Although electrical isolation of PVs with radiofrequency energy for the treatment of AF is feasible, it is associated with a significant risk of PV stenosis. Cryoablation is a new alternative therapy allowing ablation of tissue while preserving its underlying architecture. Methods In 52 patients with paroxysmal (n = 45) or persistent (n = 7) AF, PV isolation using the CryoCor cryoablation system (CyroCor Inc., San Diego, California) with a 10F deflectable transvenous catheter was performed as guided by ostial PV potentials. Cryoablation was applied twice at each targeted site (2.5 to 5 min/application). Computed tomography (CT) of the thorax was performed at baseline and at 3 and 12 months to evaluate for PV stenosis. Results All targeted PVs were completely isolated in 49 (94%) of 52 of patients. Of 152 PVs targeted, 147 (97%) were successfully isolated (mean 3.0 PVs isolated per patient). After a mean period of 12.4 ± 5.5 months of follow-up, 37 (71%) of 52 patients had no recurrence of AF or were clinically improved, including 29 patients (56%) who had no recurrence of AF with (n = 11) or without the use of anti-arrhythmic drugs. At 3 and 12 months, the CT scan showed no evidence of PV stenosis associated with cryoablation in any patients. Conclusions Transvenous catheter cryoablation is an effective method to create PV electrical isolation for the treatment of AF. A clinically satisfactory result can be achieved in 71% of patients with AF, without the risk of PV stenosis.

Septal Activation in Patients with LBBB and Heart Failure.Introduction: Little is known about the septal activation pattern in patients with heart failure and left bundle branch block (LBBB-HF). Methods and Results: The right ventricular (RV) and left ventricular (LV) activation patterns of 12 patients (mean age 67 ± 11 years) with LBBB-HF and 5 patients (mean age 45 ± 14) with normal hearts were studied during sinus rhythm using a three-dimensional mapping system. The etiology of HF was myocardial infarction (n = 4) or idiopathic dilated cardiomyopathy (n = 8). In patients with LBBB-HF, endocardial activation usually started before the onset of the surface QRS complex on the RV free wall. Latest RV activation occurred in the basal region, and total RV activation time was longer than in patients with normal hearts. In patients with LBBB-HF, the left septum was activated via slowly conducting LBB or via right-to-left transseptal conduction. In both patients with LBBB-HF and those with normal hearts, latest LV activation occurred either in the posterior or posterolateral-basal region. Conduction velocity was slower in the peri-scar region, in patients with previous myocardial infarct and globally slow, in patients with idiopathic dilated cardiomyopathy. Conclusion: The two types of left septal activation observed in patients with LBBB-HF may have consequences for biventricular hemodynamic performance. Conduction slowing along the LV, regionally or globally, suggests a contribution outside the specific conduction system in the ECG pattern of LBBB. (J Cardiovasc Electrophysiol, Vol. 14, pp. 135-141, February 2003)

Atrial Defibrillation Pathway. Introduction: Previous studies have demonstrated significant failure in converting atrial fibrillation (AF) using a conventional ventricular pathway. The aim of this study was to assess the benefit of incorporating a coronary sinus (CS) lead into the atrial defibrillation pathway in atrial defibrillation threshold (ADFT) reduction in patients with persistent AF. Methods and Results: This study was a prospective, randomized assessment of shock configuration on ADFT in 18 patients undergoing elective internal cardioversion for persistent AF (mean AF duration: 8 ′ 9 months). The lead system included a dual-coil defibrillation lead (Endotak DSP, Guidant) with a distal right ventricular (RV) electrode and a proximal superior vena cava (SVC) electrode, a CS lead (Perimeter, Guidant), and a left pectoral cutaneous electrode (Can). In each patient, dual step-up ADFTs were determined for each of three vectors: (1) RV → SVC+Can; (2) CS → SVC+Can; and (3) RV → CS+SVC+Can (group 1, n = 8) or RV+CS → SVC+Can (group 2, n = 10), using R wave-synchronized biphasic shocks. Successful defibrillation was achieved in all patients without any ventricular proarrhythmia. ADFT of CS -> SVC+Can (11.8 ′ 5.6 J) was significantly lower than ADFT of RV → SVC+Can (16.5 ′ 7.8 J, P = 0.021). ADFT of CS → SVC+Can was similar to RV → CS+SVC+Can (group 1: 12.0 ′ 6.5 J vs 17.4 ′ 4.8 J, P = 0.16), but it was significantly higher than RV+CS → SVC+Can (group 2: 9.0 ′ 3.9 J vs 11.6 ′ 5.0 J, P = 0.049). Conclusion: Patients with persistent AF of substantial duration can be reliably cardioverted using a conventional implantable cardioverter defibrillator (ICD) lead set; however, the incorporation of a CS lead to the conventional ICD lead configuration significantly lowered ADFT. The optimal shock vector that incorporates a CS lead for atrial defibrillation requires future studies.

TSE, H.-F., et al.: Effect of Coexisting Cardiovascular Disease on the Long-Term Efficacy and Safety of the Implantable Atrial Defibrillator. The long-term efficacy and safety of implantable atrial defibrillator (IAD) therapy in patients with AF and cardiovascular disease is unclear. The aim of this study was to evaluate the efficacy and safety of IAD therapy in patients with and without coexisting cardiovascular disease. In 115 patients implanted with an IAD, 85 patients had cardiovascular disease: 41 (48%) patients had 1 cardiovascular abnormality, 29 (35%) patients had 2, 13 (15%) patients had 3, and 2 (2%) patients had 4 different cardiovascular abnormalities. The device was programmed into a rhythm monitoring mode for the first 3-month postimplant period. All defibrillation therapy was performed under physician supervision to monitor safety and efficacy. After this initial monitoring period, patients were allowed to activate their device away from the hospital or clinic. A total of 357 spontaneous AF episodes occurred in 83 (72%) patients during observed operation and the mean shock efficacy was 93.5 ± 20.3% (lower 95% confidence interval [CI] 89.8%). As of the last follow-up, 58 (55%) patients had transition to receive nonphysician observed therapy. Forty-two (72%) patients had experienced 332 episodes of AF for which they had received device therapy away from the hospital/clinic (mean shock efficacy 90.5 ± 39.7%). The presence of hypertension, valvular heart disease, and ischemic heart disease did not affect the shock efficacy of the IAD during physician observed and nonobserved therapy (P > 0.05). However, the presence of congestive heart failure was associated with a lower clinical efficacy during observed and nonobserved therapy (P < 0.05). Overall, 5,262 shocks have been delivered with the IAD without any episode of proarrhythmia. The observed proarrhythmic risk was 0%, with an estimated maximum proarrhythmic risk of 0.06% per shock (95% upper CI). A stand-alone IAD appears to be safe in the presence of cardiovascular disease. The lower clinical efficacy for AF associated with congestive heart failure might be related to a higher rate of early reinitiation of AF after defibrillation.

Introduction: Catheter-based cryoablation has been shown to produce punctate and effective cardiac lesions to treat focal targets. However, sequential applications are required to produce a continuous linear lesion needed to cure macroreentrant arrhythmias with large critical isthmuses. The purpose of this study was to compare and contrast linear cardiac lesions produced with sequential applications using a novel cryoablation system to those produced using radiofrequency (RF) energy. Methods and Results: Seven mongrel dogs were prepared for femoral venous insertion of the ablation catheter (either a 10-French, 6-mm tipped, bipolar cryoablation catheter (N = 5, cryo group) or a 7-French, 4-mm tipped, bipolar RF ablation catheter (N = 2, RF group)). Ablation of the cavotricuspid isthmus was performed by delivering applications at sequential locations across the isthmus. The cryo group received 6 to 10 (mean 8 ± 1.4), 5-minute applications at 3 to 5 separate sites with a mean nadir temperature of −74.5 ± 1.6°C. Each dog in the RF group received 9, 90-second applications with a mean temperature and power of 62 ± 0°C and 32 ± 3.6 W. No acute or chronic complications were associated with either form of ablation. Immediately and six weeks after the index procedure, electroanatomical mapping showed the presence of bidirectional isthmus conduction block in all dogs. Gross and histopathologic examination revealed the presence of linear lesions, which were continuous and transmural. Conclusion: Similar to RF ablation, catheter-based cryoablation can produce linear, transmural lesions in the cavotricuspid isthmus resulting in permanent bidirectional isthmus conduction block.

Predictors of Survival in Postinfarct VT. Introduction: The aim of this study was to determine the predictive value of echocardiographic parameters of systolic left ventricular (LV) dysfunction for survival in a group of patients with “mappable” ventricular tachycardia (VT) after myocardial infarction who underwent radiofrequency ablation (RFA) of their clinical VT(s). Methods and Results: RFA of at least one inducible, “mappable,” and clinical VT was attempted in 61 patients. In total, 63 (79%) of 80 target clinical VTs were ablated successfully, such that clinical VT(s) were noninducible in 49 (80%) of 61 patients. At the last recorded follow-up (range 2 to 98 months; mean 21 ± 20), nonfatal VT recurrences were observed in 11 (22%) patients; 10 (16%) patients died. On univariate analysis, a higher LV end-diastolic volume (LVEDV; P = 0.008) and, by multivariate analysis, applying backward selection of variables, older age (P = 0.03) with a higher LVEDV (P = 0.003) predicted patients more likely to die. When age and LV ejection fraction (LVEF) were excluded, LV end-systolic diameter (LVESD; P = 0.007) was the most significant predictor of survival. Conclusion: In our patient population with postinfarct VT who underwent RFA of mappable clinical VT(s), LVEF did not predict survival. In this group of patients with overall low mean LVEF (

There is limited literature available regarding PV (pulmonary vein) stenosis management. Starting from its incidence, subsequent follow up using imaging technologies to monitor the success and the way of managing different groups pose varied opinions. However, with newer technological advancements and better understanding of mechanism of the atrial fibrillation ablation, the incidence of PV stenosis secondary to catheter ablation is declining. This paper highlights the current trends and future of management of PV stenosis secondary to catheter ablation for atrial fibrillation.

Background —A recent study has shown that the implantable atrial defibrillator can restore sinus rhythm in patients with recurrent atrial fibrillation when therapy was delivered under physician observation. The objective of this study was to evaluate the safety and efficacy of ambulatory use of the implantable atrial defibrillator. Methods and Results —An atrial defibrillator was implanted in 105 patients (75 men; mean age, 59±12 years) with recurrent, symptomatic, drug-refractory atrial fibrillation. After successful 3-month testing, patients could transition to ambulatory delivery of shock therapy. Patients completed questionnaires regarding shock therapy discomfort and therapy satisfaction using a 10-point visual-analog scale (1 represented “not at all,” 10 represented “extremely”) after each treated episode of atrial fibrillation. During a mean follow-up of 11.7 months, 48 of 105 patients satisfied criteria for transition and received therapy for 275 episodes of atrial fibrillation. Overall shock therapy efficacy was 90% with 1.6±1.2 shocks delivered per episode (median, 1). Patients rated shock discomfort as 5.2±2.4 for successful therapy and 4.2±2.2 for unsuccessful therapy ( P >0.05). The satisfaction score was higher for successful versus unsuccessful therapy (3.4±3.3 versus 8.7±1.3, P Conclusions —Ambulatory use of an implantable atrial defibrillator can safely and successfully convert most episodes of atrial fibrillation, often requiring only a single shock. Successful therapy is associated with high satisfaction and only moderate discomfort.

The purpose of this study was to evaluate the use of a new 2-lead system for detection of atrial fibrillation (AF) and atrial defibrillation.In 16 patients undergoing elective cardioversion of AF, a 2-lead system was compared with the conventional 3-lead system in a randomized trial. The new 2-lead system consisted of a catheter with a distal bipolar right ventricular electrode pair and a proximal right atrial shock electrode coil and a separate decapolar defibrillation catheter in the coronary sinus. For the 3-lead system, an additional decapolar catheter was placed in the right atrium. AF and sinus rhythm signal amplitude detection and atrial defibrillation threshold (ADFT) were compared in each patient with both systems.Successful defibrillation was obtained in all patients. ADFT for the 2-lead system was significantly higher compared with the 3-lead system (370 +/- 112 vs 316 +/- 100 V, P.05; 9.3 +/- 5.2 vs 6.8 +/- 4.2 J, P.05). In contrast, there was an increase in impedance for the 3-lead system (77 +/- 16 ohms vs 68 +/- 13 ohms; P.05). AF had a lower signal amplitude compared with sinus rhythm for both systems (P.05), and the 2-lead system had a lower signal amplitude compared with the 3-lead system for both rhythms (P.05).The use of a 2-lead system with this configuration is not superior to the 3-lead system regarding AF signal amplitude detection and ADFT. Further study is needed with implantable-quality leads in place of the temporary catheters used in this study.

OBJECTIVESWe sought to evaluate the number and duration of device-treated and self-terminating, nontreated episodes of atrial fibrillation (AF) after implantation of the Metrix Atrioverter.BACKGROUNDA recent study has shown that the Atrioverter can rapidly restore sinus rhythm in patients with AF; however, the effect of the device on the clinical course of the arrhythmia in these patients is unknown.METHODSThe Atrioverter was implanted in 51 patients with symptomatic, recurrent, drug-refractory AF. The device was programmed to periodically monitor the cardiac rhythm. Defibrillation of AF episodes was performed under physician observation.RESULTSDuring a mean follow-up of 260 ± 144 days, 1,161 episodes of AF were observed during valid monitoring periods in 45 of 51 patients. Forty-one patients experienced 231 episodes for which they sought defibrillation therapy. The average duration of the treated episodes during valid monitoring periods (190 of 231 episodes in 39 of 41 patients) was significantly longer than that of the nontreated episodes (38 ± 44 vs. 10 ± 8 h; p < 0.05). The time between episodes requiring Atrioverter therapy increased, and the risk of having an episode requiring treatment decreased. No changes were observed in the number and duration of the short-lasting, nontreated episodes as time since implantation of the device increased.CONCLUSIONSIn patients with symptomatic, recurrent, drug-refractory AF, the frequency of long-lasting episodes, which were treated under observation with repeated defibrillation using the Atrioverter, decreased. The number and duration of short-lasting, nontreated episodes did not change during the 20-month study period. The effect of ambulatory use of the device on the recurrence of short-lasting episodes needs to be evaluated.

A 65-year-old man with persistent atrial fibrillation (AF) underwent laser balloon (HeartLight, CardioFocus, Marlborough, Massachusetts) ablation of all 4 pulmonary veins (PVs) 30 months ago. The minimal dose of 5.5 W was used for 30 s in areas overlapping with blood. Seven watts was used for

Background —During atrial fibrillation, electrophysiological changes occur in atrial tissue that favor the maintenance of the arrhythmia and facilitate recurrence after conversion to sinus rhythm. An implantable defibrillator connected to right atrial and coronary sinus defibrillation leads allows prompt restoration of sinus rhythm by a low-energy shock. The safety and efficacy of this system, called the Atrioverter, were evaluated in a prospective, multicenter study. Methods and Results —The study included 51 patients with recurrent atrial fibrillation who had not responded to antiarrhythmic drugs, were in New York Heart Association Heart failure class I or II, and were at low risk for ventricular arrhythmias. The atrial defibrillation threshold had to be ≤240 V during preimplant testing. Atrial fibrillation detection, R-wave shock synchronization, and defibrillation threshold were tested at implantation and during follow-up. Shock termination of spontaneous episodes of atrial fibrillation was performed under physician observation. Results are given after a minimum of 3 months of follow-up. During a follow-up of 72 to 613 days (mean, 259±138 days), 96% of 227 spontaneous episodes of atrial fibrillation in 41 patients were successfully converted to sinus rhythm by the Atrioverter. In 27% of episodes, several shocks were required because of early recurrence of atrial fibrillation. Shocks did not induce ventricular arrhythmias. Most patients received antiarrhythmic medication during follow-up. In 4 patients, the Atrioverter was removed: in 1 because of infection, in 1 because of cardiac tamponade, and in 1 because of frequent episodes of atrial fibrillation requiring His bundle ablation. Conclusions —With the Atrioverter, prompt and safe restoration of sinus rhythm is possible in patients with recurrent atrial fibrillation.

Background —Accurate mapping of the site of origin and activation sequence of a cardiac arrhythmia is essential for a successful catheter ablation procedure. To achieve this, precise and reproducible catheter manipulation is mandatory. The aim of this study was (1) to assess the accuracy of a new nonfluoroscopic mapping system in humans and (2) to report the first result of endocardial activation mapping with this system during sinus rhythm and several types of supraventricular and ventricular tachycardias. Methods and Results —Fifteen patients were studied. Accuracy measurements were performed in 5 of them (patients 5, 6, 7, 8, and 14). The distances between two subsequent catheter positions in the inferior caval vein as determined by the nonfluoroscopic mapping system were compared with measurements made with calipers by four independent investigators using identification marks on the catheter shaft. The difference between these two methods was 0.95±0.8 mm. In 15 patients, activation of the right atrium and/or the right or left ventricle was recorded during sinus rhythm. Three-dimensional activation maps were constructed in patients with atrial and ventricular tachycardias and Wolff-Parkinson-White syndrome. Conclusions —With this new nonfluoroscopic mapping technique, accurate positioning of the catheter tip is possible. A three-dimensional activation map can be reconstructed during sinus rhythm and during supraventricular and ventricular tachycardias of different compartments of the heart.

Electrode Length for Atrial Defibrillation. Introduction: Catheter-based electrodes have been used previously to terminate episodes of atrial fibrillation in animals and man. Typically, these electrodes span 6 to 7 cm, and lowest energy requirements are achieved when these electrodes are positioned in the distal coronary sinus and in the right atrium. The purpose of this study was to evaluate the use of longer electrode lengths for atrial defibrillation. Methods and Results: In 15 patients, two decapolar catheters were inserted, one into the distal coronary sinus and one in the right atrium. To provide longer electrodes lengths, a third catheter was inserted and alternated positioned in the right atrium or coronary sinus. A 6-cm electrode span was obtained by using the distal 8 rings on the coronary sinus catheter or 8 consecutive electrodes on the right atrial catheter and increased from 6 to 11 cm by connecting consecutive, nonoverlapping rings of the third catheter with the 10 rings of the initial right atrial or coronary sinus catheter. Atrial defibrillation thresholds were determined twice, in a randomized order, in each patient for each of the three combinations of electrode lengths. All 15 patients could he successfully converted to sinus rhythm without complications; however, one patient could be converted reproducibly with only 2 of the 3 electrode combinations. Mean thresholds were 306 ± 102 V, 5.9 ± 4.0 J for the 6 cm/6 cm electrode length combination with an impedance of 72 ± 18 ω. For the electrode combination using the 11-cm electrode in the right atrium, the defibrillation threshold was 296 ± 107 V, 5.8 ± 3.9 J with an impedance of 61 ± 17 ω and was 294 ± 91 V, 5.6 ± 3.6 J with an impedance of 55 ± 11 ω for the 11-cm electrode in the coronary sinus. There were no significant differences in defibrillation voltage or energy (P > 0.05) associated with the longer electrode lengths; however, the longer electrode lengths did significantly lower shock impedance (P < 0.05). Conclusion: The use of longer electrodes, when using the right atrium to coronary sinus shock vector, does not lower the defibrillation requirements for restoration of sinus rhythm.

Objectives—To examine the effect of isoprenaline on slow and fast pathway properties and tachycardia initiation. Design—Consecutive patients, prospective study. Setting—Referral centre for cardiology, academic hospital. Patients—24 patients suffering from common type atrioventricular nodal re-entrant tachycardia (AVNRT). Interventions—Programmed electrical stimulation and radiofrequency catheter ablation of the slow pathway. Measurements and main results—AVNRT was induced before and after the administration of isoprenaline in nine patients (group 1), before isoprenaline only in five (group 2), and after isoprenaline only in 10 (group 3). The anterograde effective refractory period of the fast pathway was prolonged significantly during isoprenaline administration in group 1 (405 (31) v 335 (34) ms, p

Sudden death can be the first manifestation of the Wolff-Parkinson-White (WPW) syndrome. The underlying mechanism being atrial fibrillation with a very high ventricular rate, because of a short anterograde refractory period of the accessory atrioventricular pathway (AP), deteriorating into ventricular fibrillation. Information on the anterograde refractory period of the AP is therefore important to recognize asymptomatic people with the WPW ECG at risk for dying suddenly. Several noninvasive tests are available to identify the low risk patient. Decision making when to interrupt the AP in asymptomatic WPW patients not at low risk requires an invasive study to document the electrophysiological properties of the AP and to determine its exact location.

We performed radiofrequency catheter ablation of idiopathic ventricular tachycardia in six children. In four, the ventricular tachycardia originated in the left ventricle, in two it originated in the right ventricular outflow tract. In 5/6 (83%) the RF procedure was successful; there were no complications.

Monomorphic VT in HCM. Introduction: Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm. Methods and Results: The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal internals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds. Conclusion: Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.

OBJECTIVE--To examine the value of programmed electrical stimulation of the heart in predicting sudden death in patients receiving amiodarone to treat ventricular tachyarrhythmias after myocardial infarction. DESIGN--Consecutive patients; retrospective study. SETTING--Referral centre for cardiology, academic hospital. PATIENTS--106 patients with ventricular tachycardia (n = 77) or ventricular fibrillation (n = 29) late after myocardial infarction. INTERVENTIONS--Programmed electrical stimulation was performed while on amiodarone treatment for at least one month. MEASUREMENTS AND MAIN RESULTS--In 80/106 patients either ventricular fibrillation (n = 15) or sustained monomorphic ventricular tachycardia (n = 65) was induced. After a mean follow up of 50 (SD 40) months (1-144), 11 patients died suddenly and two used their implantable cardioverter debfibrillator. By multivariate analysis two predictors for sudden death were found: (1) inducibility of ventricular fibrillation under amiodarone treatment (P << 0.001), and (2) a left ventricular ejection fraction of < 40% (P < 0.05). The survival rate at one, two, three, and five years was 70%, 62%, 62%, and 40% respectively for patients in whom ventricular fibrillation was induced, and 98%, 96%, 94%, 94% for patients with induced sustained monomorphic ventricular tachycardia. Where there was no sustained arrhythmia, five year survival was 100%. CONCLUSIONS--In patients receiving amiodarone because of life threatening ventricular arrhythmias after myocardial infarction, inducibility of ventricular fibrillation, but not of sustained monomorphic ventricular tachycardia, indicates a high risk of sudden death.

Aim Only a few studies have investigated the effect of large tip sizes for catheter-based cryoablation (cryo). This study evaluates the safety and efficacy of cryo of the cavotricuspid isthmus (CTI) using three cryocatheter-tip sizes. Methods and results Forty-five consecutive patients with common atrial flutter (AFL) underwent cryo of the CTI using a 6.5, a 10, or a novel 15 mm catheter-tip. Single applications of 3 min were delivered at each site along the CTI. Baseline characteristics of the three groups were comparable. The overall acute success rate was 89% and there was no difference with respect to the tip electrode size ( P > 0.05). Fewer applications were required for a 10 mm (6 ± 2, range 3–7) and a 15 mm (6 ± 1, range 4–8) compared with a 6.5 mm catheter-tip (8 ± 3, range 4–14; P < 0.05). Procedure time was significantly shorter with the largest tip electrode (89 ± 26 min vs. 132 ± 28 min (6.5 mm tip), P < 0.05). No complications occurred. After a mean follow-up of 51 ± 5 months, 43 patients (96%) were without recurrence of AFL. Conclusions A large (10 or 15 mm) cryoablation catheter-tip requires significantly fewer applications to create bidirectional CTI block compared with a 6.5 mm tip. A significant decrease in procedure time with preservation of the overall safety and efficacy supports the preference of a 15 over a 6.5 mm catheter-tip for cryoablation of AFL.

OBJECTIVE--To evaluate characteristics of patients and accessory pathways as well as additional technical factors involved in the reappearance of accessory pathway conduction after successful ablation. DESIGN--Analysis of recurrences after radiofrequency ablation. SETTING--163 consecutive patients with 167 accessory pathways. SUBJECTS--97 men and 66 women with a mean (SD) age of 36 (14) range (11 to 75) years. RESULTS--After a mean (SD) follow up of 14 (7) range (2 to 27) months, conduction recurred in 13 out of 167 (7.8%) accessory pathways. The initial manifestation of recurrence was circus movement tachycardia in 7 patients and reappearance of delta waves on a 12 lead electrocardiogram in 6 patients. The interval to the return of accessory pathway conduction ranged from 3 hours to 90 days. Age, sex, presence of multiple accessory pathways, criteria to determine the target ablation site, number and duration of radiofrequency applications, and cumulative energy did not significantly differ between the groups with recurrence and without. Recurrence was less common with concealed accessory pathways (2/44) than with overt accessory pathways (11/110). The difference was not significant. The only variable to influence the recurrences in this study group was the location of the accessory pathway. Reappearance of conduction through right sided accessory pathways occurred significantly more often than through left sided ones (8/40 v 5/114, P = 0.01). CONCLUSION--After radiofrequency ablation the recurrence rate of accessory pathways is low and there are no predictors of the risk of reappearance of conduction apart from the right sided location of the accessory pathway.

Aims Vitamin K antagonists (VKA) are currently the most frequently used drug to prevent ischaemic stroke in atrial fibrillation (AF) patients. However, VKA use has been associated with increased vascular calcification. The aim of this study was to investigate the contribution of VKA use to coronary artery calcification in low-risk AF patients. Methods and results A prospective coronary calcium scan was performed in 157 AF patients without significant cardiovascular disease (108 males; mean age 57 ± 9 years). A total of 71 (45%) patients were chronic VKA users. The duration of VKA treatment varied between 6 and 143 months (mean 46 months). No significant differences in clinical characteristics were found between patients on VKA treatment and non-anticoagulated patients. However, median coronary artery calcium scores differed significantly between patients without and patients with VKA treatment [0, inter-quartile range (IQR) 0–40, vs. 29, IQR 0–184; P = 0.001]. Mean coronary calcium scores increased with the duration of VKA use (no VKA: 53 ± 115, 6–60 months on VKA: 90 ± 167, and >60 months on VKA: 236 ± 278; P < 0.001). Multivariable logistic regression analysis revealed that age and VKA treatment were significantly related to increased coronary calcium score. Conclusion Patients using VKA show increased levels of coronary calcification. Age and VKA treatment were independently related to increased coronary calcium score.

An otherwise healthy 19-year-old woman presented with a history of palpitations. A 12-lead ECG demonstrated runs of monomorphic, non-sustained ventricular tachycardia (VT) with left bundle-branch block morphology, right-axis deviation, suggesting an idiopathic VT from a coronary cusp (figure 1, panel B).1 Echocardiography demonstrated a structurally and functionally normal heart. She was admitted for electrophysiological evaluation and catheter ablation. Figure 1 The 12-lead ECG and endocardial recordings before (A, B), during (C) and after (D) cryoablation of the ventricular arrhythmia originating in …

An atrial defibrillator was implanted in a patient with congenitally corrected transposition of the great arteries, associated cardiac abnormalities, and persistent atrial arrhythmias. During a 15-month follow-up, 14 of 20 spontaneous episodes of his arrhythmias were successfully treated with the device. Two of these episodes were converted to sinus rhythm during ambulatory use of the device. Successful use of the device required implantation of a third defibrillation lead in the persistent left-sided superior caval vein and rigid control of congestive heart failure. An atrial defibrillator may be a valid treatment option in patients with congenital heart disease crippled by atrial fibrillation.

The Metrix™ Atrioverter Expanded Indication Trial evaluates the safety and efficacy of an implantable atrial defibrillator in patients with symptomatic, recurrent and drug refractory atrial fibrillation who also have structural heart disease. In this ongoing multicenter study, all patients are anticoagulated and concomitant antiarrhythmic drug treatment is left to the preference of the physician. Holter monitoring is performed prior to enrollment in the study. Spontaneous episodes of atrial fibrillation (AF) are treated under physician observation and when patients are ambulatory, the device is programmed in a monitoring mode. The atrial defibrillation threshold is measured at implantation and at 3, 6 and 12 months thereafter. The performance of the AF detection and R-wave synchronization algorithm is assessed at implantation, at regular follow-up intervals, and each time the patient visits the hospital for treatment of a spontaneous episode of AF. An echocardiogram is performed prior to implantation, at 3 and 6 month follow-up and for patients with an implanted heart valve, after 20 and 50 atrial defibrillation shocks have been delivered. The study started on October 1997 and will end after the last patient enrolled completes his/her six-month post-implantation follow-up, unless a safety issue arises. As of September 1998, 6 patients (2 patients with tachycardia induced cardiomyopathy, 1 patient with a mitral valve prosthesis, 2 patients with hypertrophic cardiomyopathy and 1 patient with congenital heart disease) have been enrolled in the study. Over 350 shocks have been delivered for atrial defibrillation testing or termination of spontaneous AF episodes. There have been no reported cases of ventricular proarrhythmia or inaccurately synchronized shocks and no complications of device therapy in this population.

The safety of the combination of heparin and ridogrel therapy and its antiplatelet efficacy was examined in the setting of percutaneous transluminal coronary angioplasty (PTCA). In 32 patients without known aspirin intake for 10 days before PTCA, therapy with ridogrel (300-mg intravenous bolus) was begun just before PTCA and continued orally at a dose of 300 mg twice daily until discharge. Heparin was administered as a 10,000 IU bolus dose before PTCA and followed by an intravenous infusion at a rate of 1,000 IU/hour for 24 hours. Bleeding problems at the arterial entry site occurred in 13 patients, which required a blood transfusion in only 2 patients. One patient underwent emergency bypass surgery without specific problems of hemostasis. Ridogrel virtually eliminated thromboxane B2 from the serum (29,990 +/- 6,555 pg/0.1 ml before vs 63 +/- 7 pg/0.1 ml at 2 hours after ridogrel), with a concomitant increase in serum 6-keto-prostaglandin F1 alpha (511 +/- 34 pg/0.1 ml before vs 1,190 +/- 146 pg/0.1 ml at 24 hours after ridogrel). There were no acute reocclusions in the ridogrel-treated patients, whereas acute reocclusions occurred in 5.6% of the patients taking the standard aspirin + heparin regimen during the same period. Furthermore, at 6-month clinical follow-up patients treated with ridogrel compared favorably with those receiving standard treatment.

Background —The low shock energy used during internal atrial defibrillation may decrease the need for sedation during defibrillation with an implantable atrial defibrillator. Methods and Results —The atrial defibrillator (Metrix Atrioverter) was implanted in 12 patients. During the in-hospital treatment of atrial fibrillation (AF) episodes, intravenous sedation was given only on patient request. The Atrioverter was programmed for ambulatory therapy in 4 patients. Efficacy, number of shocks delivered, and sedation requirements were recorded. A total of 393 shocks (1.8±1.6 shocks/AF episode) were delivered to treat 213 AF episodes; 85 of 213 AF episodes (40%) were treated away from the hospital. Sinus rhythm was restored in 195 AF episodes (92%). Five patients never requested sedation. No sedation was needed for ambulatory-treated AF episodes. During the treatment of 26 of 213 AF episodes (12%), 75 shocks were delivered after patients received sedation. The number of shocks required to treat an AF episode determined the need for sedation (4.3±2.1 shocks for AF episodes requiring sedation versus 2±1 shocks for AF episodes requiring no sedation; P Conclusions —This study suggests that, in a selected group of patients, AF can be treated with Atrioverter therapy without sedation. Successful ambulatory treatment of AF episodes with the Atrioverter, programmed to deliver ≤2 shocks, did not require sedation. When multiple shocks were required to treat an AF episode, the need for sedation increased and included patients initially not requesting sedation.

In some patients with atrial fibrillation, atrial flutter develops after administration of class IC antiarrhythmic drugs, the so-called class IC atrial flutter. Radiofrequency ablation of the right atrial isthmus results in clinical improvement in 85% of patients and provides an alternative management strategy for a subset of patients with therapy-resistant atrial fibrillation.

Two mechanisms are generally proposed to explain right precordial ST-segment elevation in Brugada syndrome: 1) right ventricular (RV) subepicardial action potential shortening and/or loss of dome causing transmural dispersion of repolarization; and 2) RV conduction delay. Here we report novel mechanistic insights into ST-segment elevation associated with a Na+ current ( INa) loss-of-function mutation from studies in a Dutch kindred with the COOH-terminal SCN5A variant p.Phe2004Leu. The proband, a man, experienced syncope at age 22 yr and had coved-type ST-segment elevations in ECG leads V1 and V2 and negative T waves in V2. Peak and persistent mutant INa were significantly decreased. INa closed-state inactivation was increased, slow inactivation accelerated, and recovery from inactivation delayed. Computer-simulated INa-dependent excitation was decremental from endo- to epicardium at cycle length 1,000 ms, not at cycle length 300 ms. Propagation was discontinuous across the midmyocardial to epicardial transition region, exhibiting a long local delay due to phase 0 block. Beyond this region, axial excitatory current was provided by phase 2 (dome) of the M-cell action potentials and depended on L-type Ca2+ current (“phase 2 conduction”). These results explain right precordial ST-segment elevation on the basis of RV transmural gradients of membrane potentials during early repolarization caused by discontinuous conduction. The late slow-upstroke action potentials at the subepicardium produce T-wave inversion in the computed ECG waveform, in line with the clinical ECG.

Background— The coexistence of atrial fibrillation (AF) and atrial flutter (AFL) is well recognized. AF precedes the onset of AFL in almost all instances. We evaluated the effect of 2 ablation strategies in patients with paroxysmal AF (PAF) and AFL. Methods and Results— Ninety-eight patients with PAF/AFL were prospectively recruited to undergo pulmonary vein cryoisolation (PVI). Those with at least 1 episode of sustained common-type AFL were assigned to cavotricuspid isthmus cryoablation followed by a 6-week monitoring period and a subsequent PVI (n=36; group I). Patients with PAF only underwent PVI (n=62; group II). The study included 76 men with a mean age of 50±10 years. Most patients (76 [78%]) had no structural heart disease. When the 2 groups were compared, residual AF after a blanking period of 3 months after PVI occurred in 24 patients (67%) in group I versus 7 (11%) in group II ( P Conclusions— In patients with PAF and no documented common-type AFL, PVI alone prevented the occurrence of AF in 82%, whereas in patients with AFL/PAF, cavotricuspid isthmus cryoablation and PVI were used successfully to treat sustained common-type AFL but appeared to be insufficient to prevent recurrences of AF. In this population, AFL can be a sign that non–pulmonary vein triggers are the culprit behind AF or that sufficient electrical remodeling has already occurred in both atria, and thus a strategy that includes substrate modification may be required.

A 76-year-old woman with mild mitral regurgitation secondary to a mitral valve prolapse was referred for electrical cardioversion of her first episode of symptomatic atrial fibrillation. A single, 200 J, monophasic shock restored …