Radio-frequency ablation as primary management of well-tolerated sustained monomorphic ventricular tachycardia in patients with structural heart disease and left ventricular ejection fraction over 30%.

AIMS: Patients with well-tolerated sustained monomorphic ventricular tachycardia (SMVT) and left ventricular ejection fraction (LVEF) over 30% may benefit from a primary strategy of VT ablation without immediate need for a 'back-up' implantable cardioverter-defibrillator (ICD). METHODS AND RESULTS: One hundred and sixty-six patients with structural heart disease (SHD), LVEF over 30%, and well-tolerated SMVT (no syncope) underwent primary radiofrequency ablation without ICD implantation at eight European centres. There were 139 men (84%) with mean age 62 ± 15 years and mean LVEF of 50 ± 10%. Fifty-five percent had ischaemic heart disease, 19% non-ischaemic cardiomyopathy, and 12% arrhythmogenic right ventricular cardiomyopathy. Three hundred seventy-eight similar patients were implanted with an ICD during the same period and serve as a control group. All-cause mortality was 12% (20 patients) over a mean follow-up of 32 ± 27 months. Eight patients (40%) died from non-cardiovascular causes, 8 (40%) died from non-arrhythmic cardiovascular causes, and 4 (20%) died suddenly (SD) (2.4% of the population). All-cause mortality in the control group was 12%. Twenty-seven patients (16%) had a non-fatal recurrence at a median time of 5 months, while 20 patients (12%) required an ICD, of whom 4 died (20%). CONCLUSION: Patients with well-tolerated SMVT, SHD, and LVEF > 30% undergoing primary VT ablation without a back-up ICD had a very low rate of arrhythmic death and recurrences were generally non-fatal. These data would support a randomized clinical trial comparing this approach with others incorporating implantation of an ICD as a primary strategy.

Incessant atrio-ventricular node reentrant tachycardia induced by unapparent dual atrio-ventricular node conduction.

We present the case of a patient with incessant slow-fast atrio-ventricular (AV) node reentrant tachycardia induced by dual AV node conduction with aborted conduction to the ventricles. The unapparent conduction over the slow pathway was suspected here because of spontaneous nodal echoes without QRS complexes occurring during sinus rhythm, manifested as isolated premature atrial beats and which repetitively induced the tachycardia.

Transseptal implantation of a left ventricular pacing lead for an ectopic location of the coronary sinus ostium in the left atrium.

Congenital abnormalities of the coronary sinus (CS) are rare but can be responsible for unsuccessful implantation of a cardiac resynchronization therapy device. We report the case of an ectopic drainage of the CS in the left atrium. A left ventricular lead was implanted by the transseptal route.

Atrial oversensing by an LV lead during typical flutter: the interest of electronic repositioning.

Occurrence of supraventricular tachycardia is a common cause of clinical impairment for patients implanted with CRT devices. We report the case of atrial activity oversensing by the left ventricular (LV) lead during typical flutter, which led to LV pacing inhibition. Temporary reprogramming of the LV detection from standard bipolar to extended bipolar and cavotricuspid isthmus ablation solved this problem.

First inappropriate implantable cardioverter defibrillator therapy is often due to inaccurate device programming: analysis of the French OPERA registry.

AIMS: Inappropriate therapy delivered by implantable cardioverter defibrillators (ICDs) remains a challenge. The OPERA registry measured the times to, and studied the determinants of, first appropriate (FAT) and inappropriate (FIT) therapies delivered by single-, dual- and triple-chamber [cardiac resynchronization therapy defibrillator (CRT-D)] ICD. METHODS AND RESULTS: We entered 636 patients (mean age = 62.0 ± 13.5 years; 88% men) in the registry, of whom 251 received single-, 238 dual-, and 147 triple-chamber ICD, for primary (30.5%) or secondary (69.5%) indications. We measured times to FAT and FIT as a function of multiple clinical characteristics, examined the effects of various algorithm components on the likelihood of FAT and FIT delivery, and searched for predictors of FAT and FIT. Over 22.8 ± 8.8 months of observation, 184 patients (28.9%) received FAT and 70 (11.0%) received FIT. Ventricular tachycardia (VT) was the trigger of 88% of FAT, and supraventricular tachycardia was the trigger of 91% of FIT. The median times to FIT (90 days; range 49-258) and FAT (171 days; 50-363) were similar. The rate of FAT was higher (P <0.001) in patients treated for secondary than primary indications, while that of FIT were similar in both groups. Out of 57 analysable FIT, 27 (47.4%) could have been prevented by fine tuning the device programming like the sustained rate duration or the VT discrimination algorithm. CONCLUSIONS: First inappropriate therapy occurred in 11% of 636 ICD recipients followed for ∼2 years. Nearly 50% of FIT could have been prevented by improving device programming.

Microvolt T-wave alternans in short QT syndrome.

BACKGROUND: T-wave alternans (TWA) is an accepted marker of risk for malignant ventricular arrhythmias, for which prognosis value has been established in different populations. Short QT syndrome (SQTS) is a very rare primary electrical disease carrying the risk of ventricular fibrillation. TWA in SQTS has not been evaluated yet. METHODS: Thirteen patients with SQTS (QT = 308 ± 16 ms, QTc = 329 ± 10 ms, heart rate = 69 ± 8 beats/min) underwent microvolt TWA measurement using spectral analysis. TWA testing was performed using Heartwave II (Cambridge Heart™, Inc., Bedford, MA, USA) during bicycle exercice and classified as negative, positive, or indeterminate according to the published standards for clinical interpretation. RESULTS: Twelve patients were male (mean age 23 ± 5 years). Five were asymptomatic, three presented with aborted sudden cardiac death, and five with unexplained syncope. Six patients belonged to two unrelated families, while familial cases of SQTS were present for two other patients. A familial history of sudden death (SD) was present for seven patients. Ventricular fibrillation was inducible in three patients. Four patients were implanted with an implantable cardioverter-defibrillator and one presented with polymorphic ventricular tachycardia during follow-up. TWA was negative in each but one patient (indeterminate). Maximal negative heart rate was 118 ± 12 beats/min. Patients with previous SD displayed significant shorter QT and higher resting heart rate compared to the remaining cases. CONCLUSIONS: TWA testing is negative in 12 of 13 SQTS patients, even in the symptomatic or inducible ones. Measurement of TWA using conventional protocol and criteria for risk stratification in SQTS seems therefore useless.

Concealed left superior accessory pathway. Distinctive features of retrograde atrial activation and successful ablation using transseptal approach.

Concealed left superior accessory pathways are very infrequent and can be difficult to diagnose and ablate. We describe here the case of a patient presenting with reciprocating tachycardia involving superior and inferior left accessory pathways. Left superior accessory pathway was suspected because of the simultaneous retrograde atrial activation at the distal coronary sinus (CS) and His bundle lead and could be successfully ablated using transseptal catheterization.

A cardio-neurological form of laminopathy: dilated cardiomyopathy with permanent partial atrial standstill and axonal neuropathy.

We present the first form of laminopathy connected with a new mutation of the lamin A/C gene expressed by dilated cardiomyopathy and partial atrial standstill associated with Charcot-Marie-Tooth type 2 axonal neuropathy. The rapid development of the cardiac disease was controlled by medical treatment and resynchronization therapy associated with a defibrillator.

Surgical catheter ablation of ventricular tachycardia using left thoracotomy in a patient with hindered access to the left ventricle.

We report the case of a patient presenting with incessant monomorphic ventricular tachycardia resistant to antiarrhythmic drugs, and in whom usual percutaneous vascular or pericardial access to the left ventricle was hindered by mechanical aortic and mitral prosthetic valves. Because an epicardial location was suspected by electrocardiogram features and because access to the target area through the coronary sinus was not possible, we decided to perform a surgically based radiofrequency (RF) ablation. Catheter mapping of the epicardial surface through surgical left lateral thoracotomy in the operating room confirmed the epicardial location of the arrhythmogenic substrate and allowed successful RF ablation of the clinically incessant tachycardia. Combined surgical and electrophysiological approach should therefore be performed when RF ablation is needed in case of unadvisable, difficult, or failed nonsurgical percutaneous access.

Reverse left septal activation during intermittent left bundle-branch block: indirect proof for concealed retrograde left bundle-branch activation.

Concealed retrograde activation of bundle branch has been often proposed for explaining the persistence of functional rate-dependent bundle-branch block, but direct proof of such a mechanism in man has rarely been demonstrated. We report intracardiac recordings compatible with a reversal of activation of the left basal interventricular septum during intermittent left bundle-branch block. In our case, however, retrograde activation into the left bundle-branch cannot be recordable, probably due to the concealment within the muscular septal activation, even if this may explain the perpetuation of bundle-branch block according to the linking phenomenon.

Electrocardiographic biomarkers of ventricular repolarisation in a single family of short QT syndrome and the role of the Bazett correction formula.

The definition of the short QT syndrome (SQTS) is based on QT duration, but thorough QT- and T-wave evaluation has not been performed to date. To evaluate the influence of QT rate-correction formulas in SQTS diagnosis, 12-lead electrocardiograms (ECGs) were recorded in 27 subjects from a single family with SQTS. Based on QT duration corrected by Bazett formula (QTc), 4 men were considered to have SQTS (QTc

Prevalence of typical atrial flutter with reentry circuit posterior to the superior vena cava: use of entrainment at the atrial roof.

AIMS: Upper turn-around of the reentry circuit in typical atrial flutter (AF) is classically described to be located in front of the superior vena cava (SVC), but circuits posterior to the SVC as well as lower loop reentry (LLR) involving only the lower part of the right atrium have been described. However, true prevalence of such AF circuits remains unknown. METHODS AND RESULTS: Fifty consecutive patients (46 men, 68 +/- 9 years old) undergoing radiofrequency (RF) ablation of typical counter-clockwise AF were prospectively investigated. Prior to RF deliverance, AF was entrained by pacing 10 ms shorter than the AF cycle length (AFCL). Post-pacing interval (PPI) at the cavotricuspid isthmus (CTI) and at the atrial roof (AR)-between SVC and the high tricuspid annulus-were determined. AR was considered to be part of the AF circuit when local PPI-AFCL was < or =20 or 30 ms or, in case of long PPI at the CTI isthmus, if difference between AR-PPI and CT-PPI was < or =10 ms. In 47 patients, CTI-PPI-AFCL was < or =30 ms (94%). Among them, AR-PPI-AFCL was >30 ms in 12 cases (25%). In the remaining three patients, AR-PPI-AFCL did not exceed CTI-PPI-AFCL by more than 10 ms. In 42 patients, CTI-PPI-AFCL was < or =20 ms (84%). Among them, AR-PPI-AFCL was >20 ms in 16 cases (39%). In the remaining eight patients, AR-PPI-AFCL was more than 10 ms longer than CTI-PPI-AFCL in only one instance. Taken together, AR PPI was >20 or >30 ms longer than AFCL or >10 ms longer than CTI PPI when prolonged in 17 (34%) and 12 patients (24%), respectively. CONCLUSION: In around a quarter to one-third of patients referred for RF ablation of typical AF, the atrial roof is not part of the circuit, thus they may present a 'posterior' variant of the typical counter-clockwise AF reentry circuit.

Radio-frequency ablation of atrial flutter: long-term results and predictive value of cavo-tricuspid isthmus bidirectional block as determined by a simplified technique.

OBJECTIVES: Complete bidirectional cavo-tricuspid isthmus (CTI) block is mandatory for radio-frequency (RF) ablation of typical atrial flutter (AF). CTI block can be assessed by a simplified method using two catheters and the technique of differential pacing, but long-term results in large series are poorly known. METHODS: CTI RF ablation was performed in 255 consecutive patients with typical AF, using one quadripolar catheter, and the ablation catheter, in association with the technique of differential pacing. RESULTS: Procedural success, as defined by documentation of complete bidirectional CTI block using limited activation mapping, positive differential pacing together with termination of ongoing AF, was achieved in 80% of patients. AF recurred in 37 patients (14%) over a mean follow-up period of 15 +/- 9 months. Two hundred and forty-one patients (94%) were finally cured, with 1.1 procedures/patient. The recurrence rate was related to the achievement of complete CTI bidirectional block (12% vs. 29%, p = 0.01). CONCLUSIONS: Long-term results of CTI ablation, employing a simplified method using the differential pacing technique, are similar to those for the standard methods using multipolar catheters. Therefore, this technique compares favorably to other established methods for such common RF procedures, especially due to its lower cost.

Incessant non-reentrant supraventricular tachycardia interrupted by apparent simultaneous wenckebach sequences along both nodal pathways.

We report a new case of non-reentrant supraventricular tachycardia, associated with tachycardia-induced cardiomyopathy fully reversible after radiofrequency (RF) ablation, together with striking features of apparent concomitant Mobitz type 1 atrioventricular (AV) block in both AV node pathways. Further analysis of the conduction patterns during the incessant non-reentrant tachycardia raised unresolved hypothesis about the involved mechanisms and further interrogations on AV node physiology.

Histopathologic effects of endocardial and epicardial percutaneous radiofrequency catheter ablation in dilated nonischemic cardiomyopathy.

We report the histological evaluation of both endocardial and epicardial radiofrequency (RF) ablation lesions in the explanted heart of a patient presenting with nonischemic dilated cardiomyopathy complicated by recurrent electrical storms. In this case, chronic RF lesions were almost transmural at the endocardial side, while remaining only superficial at the epicardial aspect, possibly because of the insulating interposed epicardial fat layer.

Reversal of dilated cardiomyopathy by the elimination of frequent left or right premature ventricular contractions.

BACKGROUND: RF ablation of frequent premature ventricular contractions (PVC) has recently been shown to improve left ventricular (LV) systolic function and dimensions in a few patients, however mainly when they originated from the right ventricular outflow tract. METHODS: RF ablation was performed at various ventricular locations in six consecutive patients with frequent, isolated PVC associated with idiopathic dilated cardiomyopathy (DCM). Baseline clinical status, PVC counts, LV ejection fraction (EF) and end-diastolic diameter (EDD) were recorded at baseline and at 6 months of follow-up. RESULTS: PVC ablation was performed in the right ventricle in four patients, the left ventricle in two patients. Before RF ablation, five patients were in New York Heart Association (NYHA) functional class I, and one patient was in class II. After RF ablation, the mean PVC count/24 h decreased from 17,717 +/- 7,100 to 268 +/- 366 (p = 0.006) while LVEF increased from 42 +/- 2.5% to 57 +/- 3% (p = 0.0001) and LVEDD decreased from 60.0 +/- 3.5 to 54.0 +/- 3.7 mm (p = 0.0009). The clinical status normalized with regression of palpitations and NYHA class. CONCLUSIONS: Elimination of frequent isolated PVC in patients with DCM with RF can normalize the clinical status and LV systolic function and dimensions, regardless of the morphology or origin of the PVC.

Mapping and ablation of ventricular fibrillation associated with long-QT and Brugada syndromes.

BACKGROUND: The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. METHODS AND RESULTS: Seven patients (4 men; age, 38+/-7 years; 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats were studied. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of premature beats after 12+/-6 minutes of radiofrequency applications. During a follow-up of 17+/-17 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmia but 1 had persistent premature beats. CONCLUSIONS: Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.

Prevalence of type 1 Brugada ECG pattern after administration of Class 1C drugs in patients with type 1 myotonic dystrophy: Myotonic dystrophy as a part of the Brugada syndrome.

BACKGROUND: Both type 1 myotonic dystrophy (MD1) and Brugada syndrome (BrS) may be complicated by conduction disturbances and sudden death. Spontaneous BrS has been observed in MD1 patients, but the prevalence of drug-induced BrS in MD1 is unknown. OBJECTIVE: The purpose of this study was to prospectively assess the prevalence of type 1 ST elevation as elicited during pharmacologic challenge with Class 1C drugs in a subgroup of MD1 patients and to further establish correlations with ECG and electrophysiologic variables and prognosis. METHODS: From a group of unselected 270 MD1 patients, ajmaline or flecainide drug challenge was performed in a subgroup of 44 patients (27 men, median age 43 years) with minor depolarization/repolarization abnormalities suggestive of possible BrS. The presence of type 1 ST elevation after drug challenge was correlated to clinical, ECG, and electrophysiologic variables. RESULTS: Eight of 44 patients (18%) presented with BrS after drug challenge. BrS was seen more often in men (26% vs 6%, P = .09) and was related to younger age (35 vs 48 years, P = .07). BrS was not correlated to symptoms, baseline ECG, HV interval, results of signal-averaged ECG, or abnormalities on ambulatory recordings. MD1 patients with BrS had longer corrected QT intervals, greater increase in PR interval after drug challenge, and higher rate of inducible ventricular arrhythmias (62% vs 21%, P = .03). Twelve patients were implanted with a pacemaker and 5 with an implantable cardioverter-defibrillator. Significant bradycardia did not occur in any patients, and malignant ventricular arrhythmia never occurred during median 7-year follow-up (except 1 hypokalemia-related ventricular fibrillation). CONCLUSION: BrS is elicited by a Class 1 drug in 18% of MD1 patients presenting with minor depolarization/repolarization abnormalities at baseline, but the finding seems to be devoid of a prognostic role.

Slower heart rate and altered rate dependence of ventricular repolarization in patients with lone atrial fibrillation.

BACKGROUND: Electrophysiological alterations in atrial fibrillation (AF) may be genetically based and may lead to changes in ventricular repolarization. Short QT syndrome is a rare channelopathy with abbreviated ventricular repolarization and a propensity for AF. AIMS: To determine if minor unrecognized forms of short QT syndrome can explain some cases of lone AF. METHODS: We prospectively compared QT intervals in 66 patients with idiopathic lone AF and 132 age- and sex-matched controls. QT intervals were measured during sinus rhythm in each of the 12 surface electrocardiogram leads and corrected using Bazett's formula (QTc). QT intervals were also corrected using other formulae. Uncorrected QT and heart rate regression lines were compared between AF patients and controls. RESULTS: AF patients presented with a slower resting heart rate (64 ± 10 beats per minute [bpm] vs 69 ± 9 bpm; P=0.0006). QTc intervals were shorter in AF patients in 11/12 electrocardiogram leads (significant in 7/12, borderline in 2/12; mean QTc 381 ± 21 ms vs 388 ± 22 ms; P=0.02). QTc intervals were also shorter in AF patients, significantly or not, using other correction formulae. For similar heart rates, uncorrected QT intervals were shorter in patients when heart rates were greater than 70 bpm and longer when heart rates were less than 60 bpm. AF patients displayed steeper QT/heart rate regression line slopes than controls (P=0.009). CONCLUSION: Heart rate is significantly slower and the rate dependence of ventricular repolarization is significantly altered in patients with lone AF compared with controls. Further study is warranted to determine if AF induces subsequent ventricular repolarization changes or if these modifications are caused by an underlying primary electrical disease.

Prevalence and prognostic role of various conduction disturbances in patients with the Brugada syndrome.

Prevalence and prognostic value of conduction disturbances in patients with the Brugada syndrome (BrS) remains poorly known. Electrocardiograms (ECGs) from 325 patients with BrS (47 ± 13 years, 258 men) with spontaneous (n = 143) or drug-induced (n = 182) type 1 ECG were retrospectively reviewed. Two hundred twenty-six patients (70%) were asymptomatic, 73 patients (22%) presented with unexplained syncope, and 26 patients (8%) presented with sudden death or implantable cardioverter-defibrillator appropriated therapies at diagnosis or during a mean follow-up of 48 ± 34 months. P-wave duration of ≥120 ms was present in 129 patients (40%), first degree atrioventricular block (AVB) in 113 (35%), right bundle branch block (BBB) in 90 (28%), and fascicular block in 52 (16%). Increased P-wave duration, first degree AVB, and right BBB were more often present in patients after drug challenge than in patients with spontaneous type 1 ST elevation. Left BBB was present in 3 patients. SCN5A mutation carriers had longer P-wave duration and longer PR and HV intervals. In multivariate analysis, first degree AVB was independently associated with sudden death or implantable cardioverter-defibrillator appropriated therapies (odds ratio 2.41, 95% confidence interval 1.01 to 5.73, p = 0.046) together with the presence of syncope and spontaneous type 1 ST elevation. In conclusion, conduction disturbances are frequent and sometimes diffuse in patients with BrS. First degree AVB is independently linked to outcome and may be proposed to be used for individual risk stratification.