The benefit of pacemaker therapy in patients with neurally mediated syncope and documented asystole: a meta-analysis of implantable loop recorder studies.

Aim: Although the efficacy of cardiac pacing in patients with neurally mediated syncope (NMS) and documented asystole is established, a more robust point estimate of the benefit, which is not possible with any individual study, is lacking. Methods and results: We undertook a meta-analysis of individual participant data from four studies that reported follow-up data on syncope recurrence with cardiac pacing in patients with NMS who had had an electrocardiographic (ECG) documentation of an asystolic event by means of implantable loop recorder (ILR). Of a total of 1046 patients, who had ILR implanted, 383 (36.6%) patients had an ECG documentation of a diagnostic event during mean follow-up of 13 ± 10 months. Of these, 201 (52%) patients, corresponding to 19.2% of the total ILRs, had an asystolic event of 12.8 ± 11.0 s duration documented and met the criteria for pacemaker therapy. Follow-up was available in 121 (60%) of those patients with asystolic events. Syncope recurred after pacing in 18 (14.9%) patients with an actuarial rate of 13% [95% confidence interval (CI) ±6] at 1 year, 21% (95%CI ±10) at 2 years, and 24% (95%CI ±11) at 3 years. On multivariable Cox regression analysis, positive tilt test response was the only significant predictor of syncope recurrence with a hazard ratio (95% CI) of 4.3 (1.4-13). On the contrary, type of asystolic event (sinus arrest or atrioventricular block), prodrome, cardiac abnormalities, number and duration of history of syncope, age, and gender were not predictors of recurrence of syncope. Conclusion: A long asystolic pause, suitable for pacemaker therapy, was found in one of five patients with ILR. After pacemaker implantation, most of these patients remained free of syncope recurrence for up to 3 years. The benefit of pacemaker was greater in patients with negative tilt test.

Pacemaker therapy in patients with neurally mediated syncope and documented asystole: Third International Study on Syncope of Uncertain Etiology (ISSUE-3): a randomized trial.

BACKGROUND: The efficacy of cardiac pacing for prevention of syncopal recurrences in patients with neurally mediated syncope is controversial. We wanted to determine whether pacing therapy reduces syncopal recurrences in patients with severe asystolic neurally mediated syncope. METHODS AND RESULTS: Double-blind, randomized placebo-controlled study conducted in 29 centers in the Third International Study on Syncope of Uncertain Etiology (ISSUE-3) trial. Patients were ≥40 years, had experienced ≥3 syncopal episodes in the previous 2 years. Initially, 511 patients, received an implantable loop recorder; 89 of these had documentation of syncope with ≥3 s asystole or ≥6 s asystole without syncope within 12 ± 10 months and met criteria for pacemaker implantation; 77 of 89 patients were randomly assigned to dual-chamber pacing with rate drop response or to sensing only. The data were analyzed on intention-to-treat principle. There was syncope recurrence during follow-up in 27 patients, 19 of whom had been assigned to pacemaker OFF and 8 to pacemaker ON. The 2-year estimated syncope recurrence rate was 57% (95% CI, 40-74) with pacemaker OFF and 25% (95% CI, 13-45) with pacemaker ON (log rank: P=0.039 at the threshold of statistical significance of 0.04). The risk of recurrence was reduced by 57% (95% CI, 4-81). Five patients had procedural complications: lead dislodgment in 4 requiring correction and subclavian vein thrombosis in 1 patient. CONCLUSIONS: Dual-chamber permanent pacing is effective in reducing recurrence of syncope in patients ≥40 years with severe asystolic neurally mediated syncope. The observed 32% absolute and 57% relative reduction in syncope recurrence support this invasive treatment for the relatively benign neurally mediated syncope. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00359203.

Cardiac resynchronization therapy in patients undergoing atrioventricular junction ablation for permanent atrial fibrillation: a randomized trial.

AIMS: On the basis of the current knowledge, cardiac resynchronization therapy (CRT) cannot be recommended as a first-line treatment for patients with severely symptomatic permanent atrial fibrillation undergoing atrioventricular (AV) junction ablation. We examined whether CRT was superior to conventional right ventricular (RV) pacing in reducing heart failure (HF) events. METHODS AND RESULTS: In this prospective, multi-centre study, we randomly assigned 186 patients, in whom AV junction ablation and CRT device implantation had been successfully performed, to receive optimized echo-guided CRT (97 patients) or RV apical pacing (89 patients). The data were analysed according to the intention-to-treat principle. During a median follow-up of 20 months (interquartile range 11-24), the primary composite endpoint of death from HF, hospitalization due to HF, or worsening HF occurred in 11 (11%) patients in the CRT group and 23 (26%) patients in the RV group [CRT vs. RV group: sub-hazard ratio (SHR) 0.37 ( 95% CI 0.18-0.73), P = 0.005]. In the CRT group, compared with the RV group, fewer patients had worsening HF [SHR 0.27 (95% CI 0.12-0.58), P = 0.001] and hospitalizations for HF [SHR 0.20 (95% CI 0.06-0.72), P = 0.013]. Total mortality was similar in both groups [hazard ratio (HR) 1.57 (95% CI 0.58-4.27), P = 0.372]. The beneficial effects of CRT were consistent in patients who had ejection fraction ≤35%, New York Heart Association Class ≥III and QRS width ≥120 and in those who did not. At multi-variable Cox regression, only CRT mode remained an independent predictor of absence of clinical failure during the follow-up [HR = 0.23 (95% CI 0.08-0.66), P = 0.007]. CONCLUSIONS: In patients undergoing 'Ablate and Pace' therapy for severely symptomatic permanent atrial fibrillation, CRT is superior to RV apical pacing in reducing the clinical manifestations of HF. (ClinicalTrials.gov number: NCT00111527).

Syncope due to idiopathic paroxysmal atrioventricular block: long-term follow-up of a distinct form of atrioventricular block.

OBJECTIVES: We present data on patients with syncope due to paroxysmal atrioventricular (AV) block unexplainable in terms of currently known mechanisms. BACKGROUND: Paroxysmal AV block is known to be due to intrinsic AV conduction disease or to heightened vagal tone. METHODS: We evaluated 18 patients presenting with unexplained syncope who had: 1) normal baseline standard electrocardiogram (ECG); 2) absence of structural heart disease; and 3) documentation, by means of prolonged ECG monitoring at the time of syncopal relapse, of paroxysmal third-degree AV block with abrupt onset and absence of other rhythm disturbances before or during the block. RESULTS: The study group consisted of 9 men and 9 women, mean age 55 ± 19 years, who had recurrent unexplained syncope for 8 ± 7 years and were subsequently followed up for as long as 14 years (4 ± 4 years on average). The patients had no structural heart disease, standard ECG was normal, and electrophysiological study was negative. In all patients, prolonged ECG monitoring documented paroxysmal complete AV block with 1 or multiple consecutive pauses (mean longest pause: 9 ± 7 s at the time of syncope); AV block occurred without P-P cycle lengthening or PR interval prolongation. During the observation time, no patient had permanent AV block; on permanent cardiac pacing, no patient had further syncopal recurrences. CONCLUSIONS: Common clinical and electrophysiological features define a distinct form of syncope due to idiopathic paroxysmal AV block characterized by a long history of recurrent syncope, absence of progression to persistent forms of AV block, and efficacy of cardiac pacing therapy.

Diagnosis, management, and outcomes of patients with syncope and bundle branch block.

AIMS: Although patients with syncope and bundle branch block (BBB) are at high risk of developing atrio-ventricular block, syncope may be due to other aetiologies. We performed a prospective, observational study of the clinical outcomes of patients with syncope and BBB following a systematic diagnostic approach. METHODS AND RESULTS: Patients with ≥1 syncope in the last 6 months, with QRS duration ≥120 ms, were prospectively studied following a three-phase diagnostic strategy: Phase I, initial evaluation; Phase II, electrophysiological study (EPS); and Phase III, insertion of an implantable loop recorder (ILR). Overall, 323 patients (left ventricular ejection fraction 56 ± 12%) were studied. The aetiological diagnosis was established in 267 (82.7%) patients (102 at initial evaluation, 113 upon EPS, and 52 upon ILR) with the following aetiologies: bradyarrhythmia (202), carotid sinus syndrome (20), ventricular tachycardia (18), neurally mediated (9), orthostatic hypotension (4), drug-induced (3), secondary to cardiopulmonary disease (2), supraventricular tachycardia (1), bradycardia-tachycardia (1), and non-arrhythmic (7). A pacemaker was implanted in 220 (68.1%), an implantable cardioverter defibrillator in 19 (5.8%), and radiofrequency catheter ablation was performed in 3 patients. Twenty patients (6%) had died at an average follow-up of 19.2 ± 8.2 months. CONCLUSION: In patients with syncope, BBB, and mean left ventricular ejection fraction of 56 ± 12%, a systematic diagnostic approach achieves a high rate of aetiological diagnosis and allows to select specific treatment.

Compliance to MADIT and MUSTT criteria for implantable cardioverter defibrillator therapy in the pre-SCD-Heft and MADIT II era. Data from a multicenter Italian study.

The follow-up of 1440 consecutive post-MI patients (68.9 ± 10.9 years) with an LVEF ≤ 40% was analyzed in 19 Italian hospitals to evaluate how many patients with clinical nonsustained VT and inducible sustained VT or VF underwent post-discharge risk assessment (RA). During 38 (range, 4-76) months follow-up, 611 patients (42.4%) qualified for and 294 (20.4%) effectively underwent RA combining LVEF assessment and Holter monitoring, 29 (2.0%) subsequently underwent programmed electrical stimulation and 19 (1.3%) received an ICD.

Sudden death in a patient with idiopathic right ventricular outflow tract arrhythmia.

Idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) and idiopathic RVOT extrasystoles are generally considered benign arrhythmias. We describe the case of a patient with typical RVOT arrhythmias without any symptoms for many years, who died suddenly the day before a planned electrophysiological study. The only disquieting signs in her clinical history were a relatively short coupling interval of premature ventricular contractions in some ECG recordings and an isolated run of polymorphic nonsustained ventricular tachycardia induced by an RVOT extrasystole during previous ECG monitoring.

A simplified biventricular defibrillator with fixed long detection intervals reduces implantable cardioverter defibrillator (ICD) interventions and heart failure hospitalizations in patients with non-ischaemic cardiomyopathy implanted for primary prevention: the RELEVANT [Role of long dEtection window programming in patients with LEft VentriculAr dysfunction, Non-ischemic eTiology in primary prevention treated with a biventricular ICD] study.

AIMS: To investigate the efficacy and safety of a cardiac resynchronization therapy with cardioverter-defibrillator (CRT-D) device with simplified ventricular tachycardia management in patients with non-ischaemic heart failure (HF) and primary prevention implantable cardioverter defibrillator (ICD) indication. METHODS AND RESULTS: Prospective, controlled, parallel, multicentre, non-randomized study enrolling 324 primary prevention non-ischaemic HF patients implanted with CRT-D devices from 2004 to 2007: Protect group, 164 patients implanted with a Medtronic Insync III Protect device and Control group, 160 patients utilizing other Medtronic CRT-D devices. Efficacy was assessed by computing appropriate and inappropriate detections and therapies during follow-up; safety compared hospitalizations and syncopal events between groups. Ninety per cent of both ventricular and supraventricular tachyarrhythmias terminated within the 13-29 beat detection interval with the Protect algorithm. The Protect group showed a significantly better event-free survival to first delivered therapy for total (P = 0.0001), appropriately treated (P = 0.002), and inappropriately treated episodes (P = 0.017). The total number of delivered shocks was significantly lower in the Protect group (22 vs. 59, P < 0.0001). In the Protect group, a significantly reduced HF hospitalization (hazard ratio 0.38, 95% CI 0.15-0.98, P = 0.044) was observed without any increase of syncope or death. CONCLUSION: A simplified CRT-D device with fixed long detection reduced overall ICD therapy burden and HF hospitalizations without entailing any additional adverse events in primary prevention non-ischaemic HF patients.

Radiofrequency catheter ablation of atrioventricular nodal re-entry tachycardia: selective approach to the slow pathway via the cephalic veins.

Inferior venous access to the right heart is not possible in some patients due to vena caval obstruction. Here we describe a case of a patient with atrioventricular nodal re-entry tachycardia where radiofrequency ablation from the inferior vena cava was impossible because of the presence of important stenosis of the distal part of the vein. Catheter ablation of the slow pathway could be performed successfully using a superior approach via the cephalic veins.

Orthostatic hypotension as cause of syncope in patients older than 65 years admitted to emergency departments for transient loss of consciousness.

BACKGROUND: Syncope due to orthostatic hypotension (OH) refers to loss of consciousness caused by hypotension induced by the upright position; it is an important risk factor for fall-related physical injuries, especially in the elderly adults. We evaluated the prevalence of OH syncope and the clinical characteristics of patients older than 65 years with syncope due to OH in the Evaluation of Guidelines in Syncope Study 2 group population. METHODS: Two hundred fifty nine patients older than 65 years consecutively admitted to the emergency department because of loss of consciousness in a period of a month were submitted to a standardized protocol approved by the European Task Force for the diagnosis of syncope; all the patients were studied by a trained physician who interacted with a central supervisor as the management of syncope was concerned, using a decision-making software. RESULTS: Prevalence of OH syncope was 12.4%. Patients with OH syncope were more likely to be affected by Parkinson's disease and by other neurological diseases. ST changes and longer values of QTc were found in OH syncope group, and they took a greater number of diuretics, nitrates, and digoxin. In multivariate analysis, Parkinson's disease (p = .001) and use of nitrates (p = .001) and diuretics (p = .020) were independently related to OH syncope. CONCLUSIONS: In patients older than 65 years, Parkinson's disease and neurological comorbidity are strictly related to OH syncope. Moreover, this study suggests the independent link between OH syncope and the use of vasoactive drugs, identifying the majority of cases as adverse drug reaction, a preventable risk factor for syncope and falls in the older population.

Reproducibility of electrocardiographic findings in patients with suspected reflex neurally-mediated syncope.

The reproducibility of electrocardiographic (ECG) recordings in syncopal recurrences and the diagnostic role of nonsyncopal arrhythmias are not well known. The objective of this study was to analyse the reproducibility of the ECG findings recorded with implantable loop recorders in 41 patients with suspected neurally-mediated syncope who were included in the International Study on Syncope of Uncertain Origin-2 study and that had > or =2 events recorded by implantable loop recorders. In these patients, the electrocardiogram obtained with the first documented syncope (index syncope) was compared with other recorded events. Twenty-two patients had > or =2 syncopes, and their electrocardiograms were reproducible in 21 (95%): 15 with sinus rhythm, 5 with asystole, and 1 with ventricular tachycardia; 1 had asystole at first syncope and sinus rhythm at recurrent syncope. In 32 patients with nonsyncopal episodes, an arrhythmia was documented in 9, and all of them had the same arrhythmia during the index syncope (100% reproducibility); conversely, when sinus rhythm was documented (23 patients) during nonsyncopal episodes, an arrhythmia was still documented in 6 during the index syncope (70% reproducibility; p = 0.0004). In conclusion, the ECG findings during the first syncope are highly reproducible in subsequent syncopes. The presence of an arrhythmia during nonsyncopal episodes is also highly predictive of the mechanism of syncope, but the presence of sinus rhythm does not rule out the possibility of arrhythmia during syncope. Therefore the finding of an arrhythmia during a nonsyncopal episode allows the etiologic diagnosis of syncope, and eventually to anticipate treatment, without waiting for syncope.

Usefulness of echo-guided cardiac resynchronization pacing in patients undergoing "ablate and pace" therapy for permanent atrial fibrillation and effects of heart rate regularization and left ventricular resynchronization.

An acute comparative study of right ventricular (RV) pacing and echocardiographically guided cardiac resynchronization pacing (CRP) was performed in patients who underwent "ablate and pace" therapy for permanent atrial fibrillation. It was hypothesized that optimized CRP guided by tissue Doppler echocardiography would exert an additive beneficial hemodynamic effect to that of rate regularization achieved through atrioventricular junction ablation. An acute intrapatient comparison of echocardiographic parameters was performed between baseline preablation values and RV pacing and CRP (performed <24 hours after ablation) in 50 patients. Optimized CRP configuration was defined as the modality of pacing corresponding to that of the shortest intra-left ventricular (LV) delay among simultaneous biventricular pacing, sequential biventricular pacing, and single-chamber pacing. The intra-LV delay was defined as the difference between the longest and the shortest activation time in the six basal segments of the left ventricle. Compared with preablation measures, the ejection fraction increased by 10.8% during RV pacing (19% in patients with intra-LV delays <47.5 ms and 3% in those with intra-LV delays >47.5 ms). Compared with RV pacing, CRP caused a 9.2% increase in the ejection fraction, a 6.8% decrease in LV systolic diameter, and a 17.3% decrease in mitral regurgitation area; LV dyssynchrony was reduced from 52 +/- 27 to 21 +/- 12 ms. Similar results were observed in patients with and without depressed systolic function and in patients with and without left bundle branch block. In conclusion, rate regularization achieved through atrioventricular junction ablation and RV pacing provides a favorable hemodynamic effect that is inversely related to the level of LV dyssynchrony. Minimizing LV dyssynchrony by means of optimized CRP yields an additional important benefit.

Recurrent unexplained palpitations (RUP) study comparison of implantable loop recorder versus conventional diagnostic strategy.

OBJECTIVES: The aim of the study was to compare the diagnostic yield and the costs of implantable loop recorder (ILR) with those of the conventional strategy in patients with unexplained palpitations. BACKGROUND: In patients with unexplained palpitations, especially in those with infrequent symptoms, the conventional strategy, including short-term ambulatory electrocardiogram (ECG) monitoring and electrophysiological study, sometimes fails to establish a diagnosis. METHODS: We studied 50 patients with infrequent (< or =1 episode/month), sustained (>1 min) palpitations. Before enrollment, patients had a negative initial evaluation, including history, physical examination, and ECG. Patients were randomized either to conventional strategy (24-h Holter recording, a 4-week period of ambulatory ECG monitoring with an external recorder, and electrophysiological study) (n = 24) or to ILR implantation with 1-year monitoring (n = 26). Hospital costs of the 2 strategies were calculated. RESULTS: A diagnosis was obtained in 5 patients in the conventional strategy group, and in 19 subjects in the ILR group (21% vs. 73%, p < 0.001). Despite the higher initial cost, the cost per diagnosis in the ILR group was lower than in the conventional strategy group (euro 3,056 +/- euro 363 vs. euro 6,768 +/- euro 6,672, p = 0.012). CONCLUSIONS: In subjects without severe heart disease and with infrequent palpitations, ILR is a safe and more cost-effective diagnostic approach than conventional strategy.

Cardioinhibitory carotid sinus hypersensitivity predicts an asystolic mechanism of spontaneous neurally mediated syncope.

AIMS: We correlated the finding of cardioinhibitory carotid sinus hypersensitivity (CSH) with that observed during a spontaneous syncopal relapse by means of an implantable loop recorder (ILR). METHODS AND RESULTS: We included 18 consecutive patients with suspected recurrent neurally mediated syncope and positive cardioinhibitory response during carotid sinus massage (max pause 5.5 +/- 1.6 s) who had subsequent documentation of a spontaneous syncope by means of an ILR. They were compared with a 2:1 age- and sex-matched group of 36 patients with a clinical diagnosis of recurrent neurally mediated syncope and negative response to carotid sinus massage, tilt testing and ATP test. Asystole >3 s was observed at the time of the spontaneous syncope in 16 (89%) of CSH patients and in 18 (50%) of the control group (P = 0.007). Sinus arrest was the most frequent finding among CSH patients but not among controls (72 vs. 28%, P = 0.003). After ILR documentation, 14 CSH patients with asystole received dual-chamber pacemaker implantation; during 35 +/- 22 months of follow-up, 2 syncopal episodes recurred in 2 patients (14%), and pre-syncope occurred in another 2 patients (14%). Syncope burden decreased from 1.68 (95% confidence interval 1.66 - 1.70) episodes per patient per year before to 0.04 (0.038-0.042) after pacemaker implant (98% relative risk reduction). CONCLUSIONS: In patients with suspected neurally mediated syncope, the finding of cardioinhibitory CSH predicts an asystolic mechanism at the time of spontaneous syncope and, consequently, suggests a possible benefit of cardiac pacing therapy.

Left ventricular electromechanical delay in patients with heart failure and normal QRS duration and in patients with right and left bundle branch block.

AIMS: We sought to define the reference values of intra-left ventricular (LV) electromechanical delay (EMD), and to assess the prevalence (and pattern) of intra-LV dyssynchrony in patients with heart failure (HF) and normal QRS and in patients with right and left bundle branch block. METHODS AND RESULTS: We used tissue Doppler imaging echocardiography and a six-LV wall model to study LV EMD in 103 patients [41 with HF and normal QRS, 22 with right bundle branch block (RBBB), and 40 with left bundle branch block (LBBB)], and in 59 controls. In controls, the median intra-LV EMD was 17 ms, (inter-quartile range 13-30); 95% of controls had a value < or =41 ms. Patients showed a longer intra-LV EMD than controls: 33 ms (20-57) in patients with normal QRS, 32 ms (23-50) in RBBB patients, and 50 ms (30-94) in LBBB patients. Intra-LV dyssynchrony (defined as intra-LV EMD >41 ms) was present in 39, 36, and 60% of the patients, respectively. On average, HF patients showed the same pattern of activation as controls, from the septum to the posterior wall, but activation times were significantly prolonged. In RBBB patients the activation sequence was directed from inferior to anterior and in LBBB from anterior to inferior wall. CONCLUSIONS: Left ventricular dyssynchrony was present in several patients with HF and normal QRS, and in patients with RBBB; conversely, 40% of LBBB patients showed values of LV EMD within the normal range. Left ventricular activation sequence was different between groups. Assessment of LV synchronicity by means of imaging techniques may be more important than QRS duration or morphology in selecting patients for cardiac resynchronization treatment.

Lack of correlation between the responses to tilt testing and adenosine triphosphate test and the mechanism of spontaneous neurally mediated syncope.

AIMS: We prospectively correlated the results of tilt testing (TT) and adenosine triphosphate test (ATP) with the findings observed during a spontaneous syncopal relapse by means of an implantable loop recorder (ILR) in patients with a clinical diagnosis of neurally mediated syncope. METHODS AND RESULTS: We included patients with three or more clinically severe syncopal episodes in the last 2 years without significant electrocardiographic and cardiac abnormalities. Patients with orthostatic hypotension and carotid sinus syncope were excluded. After ILR implantation, patients were followed until the first documented syncope. Among 392 enrolled patients, 343 underwent TT, which was positive in 164 (48%), and 180 ATP test, which was positive in 53 (29%). Syncope was documented by ILR in 106 (26%) patients after a median of 3 months. Patients with positive and negative TT had similar baseline characteristics, syncopal recurrence rate, and mechanism of syncope, but those with positive TT had more frequently no or slight rhythm variations during spontaneous syncope (45 vs. 21%, P=0.02). An asystolic pause was more frequently found during spontaneous syncope than during TT (45 vs. 21%, P=0.02), but there was a trend for those with an asystolic response during TT also to have an asystolic response during spontaneous syncope (75 vs. 37%, P=0.1). Patients with positive ATP test responses showed syncopal recurrence rates and mechanism of syncope similar to those with negative ATP tests. CONCLUSION: In patients with neurally mediated syncope, clinical characteristics, outcome, and mechanism of syncope are poorly correlated and not predicted by the results of TT and ATP test. Therefore, these tests are of little or no value in guiding specific therapy.

Effects of right ventricular pacing on intra-left ventricular electromechanical activation in patients with native narrow QRS.

Some patients with right ventricular (RV) apical pacing show contractile asynchrony of the left ventricle. Whether the asynchrony is due to RV pacing or was a preexistimg condition remains unknown. The aim of this study was to evaluate how much pacing from the RV apex affects left ventricular (LV) electromechanical activation and to assess whether the extent of LV asynchrony during RV pacing can be predicted by clinical, electrocardiographic, or echocardiographic findings obtained during spontaneous rhythm. We evaluated 56 patients with narrow QRS and preserved atrioventricular conduction who received permanent backup RV pacing. Intra-LV electromechanical activation was assessed during spontaneous rhythm and during pacing using tissue Doppler echocardiography. An abnormal intra-LV electromechanical delay (EMD) (defined as a >41-ms difference between the faster and slower activated LV wall) was found in 15 patients (27%) during spontaneous rhythm and 28 patients (50%) during RV pacing (p<0.001). Of the 9 baseline variables (age, gender, history of heart failure, QRS duration in spontaneous rhythm and during pacing, LV end-diastolic and end-systolic diameters, LV ejection fraction, and intra-LV EMD in spontaneous rhythm), an abnormal baseline intra-LV EMD and QRS duration of >85 ms were independent predictors of an abnormal intra-LV delay during RV pacing. RV apical pacing induces asynchrony of LV contractions in a substantial percentage of patients but not in all. Although normal baseline intra-LV electromechanical activation cannot exclude the development of significant asynchrony during RV pacing, the presence of preimplant LV asynchrony predicts for a worsening of this detrimental effect.

Seven-year follow-up after catheter ablation of atrioventricular nodal re-entrant tachycardia.

BACKGROUND: Radiofrequency catheter ablation is considered to be a curative therapy for patients with atrioventricular nodal re-entrant tachycardia (AVNRT). Nevertheless, there is little information available with respect to long-term results and the consequences of catheter ablation. The present study aimed to assess the long-term results (a minimum of 5 years) and clinical events. PATIENTS AND METHODS: The recurrence rate of AVNRT, the development of late atrioventricular block and the presence of other arrhythmias (atrial flutter and fibrillation) were assessed in 131 consecutive patients who were undergoing catheter ablation between January 1992 and December 1998. RESULTS: During a mean follow-up of 7.2 +/- 2.5 years, tachycardia recurred in 13 patients (10%) after a median time of 6 months (interquartile range 4-24 months) and a second procedure was perfomed. Atrioventricular block occurred in two patients (1.5%) after 1 and 13 months. Atrial fibrillation recurred in seven (44%) of 16 patients in whom atrial fibrillation or flutter was present before ablation after a median of 12 months (interquartile range 9-15 months). Overall, all these events occurred after a median of 9 months (interquartile range 4-17 months). Subsequently, no event related to the arrhythmia or to the procedure was observed. A new onset atrial fibrillation, probably not related to AVNRT, occurred late in the follow-up in a further three patients. CONCLUSIONS: Arrhythmic events are not infrequent after catheter ablation of AVNRT during the early years after ablation, but they are unlikely during the subsequent long-term follow-up.

Early application of an implantable loop recorder allows effective specific therapy in patients with recurrent suspected neurally mediated syncope.

AIMS: This prospective multicentre observational study assessed the efficacy of specific therapy based on implantable loop recorder (ILR) diagnostic observations in patients with recurrent suspected neurally mediated syncope (NMS). METHODS AND RESULTS: Patients with three or more clinically severe syncopal episodes in the last 2 years without significant electrocardiographic and cardiac abnormalities were included. Orthostatic hypotension and carotid sinus syncope were excluded. After ILR implantation, patients were followed until the first documented syncope (Phase I). The ILR documentation of this episode determined the subsequent therapy and commenced Phase II follow-up. Among 392 patients, the 1-year recurrence rate of syncope during Phase I was 33%. One hundred and three patients had a documented episode and entered Phase II: 53 patients received specific therapy [47 a pacemaker because of asystole of a median 11.5 s duration and six anti-tachyarrhythmia therapy (catheter ablation: four, implantable defibrillator: one, anti-arrhythmic drug: one)] and the remaining 50 patients did not receive specific therapy. The 1-year recurrence rate in 53 patients assigned to a specific therapy was 10% (burden 0.07 +/- 0.2 episodes per patient/year) compared with 41% (burden 0.83 +/- 1.57 episodes per patient/year) in the patients without specific therapy (80% relative risk reduction for patients, P = 0.002, and 92% for burden, P = 0.002). The 1-year recurrence rate in patients with pacemakers was 5% (burden 0.05 +/- 0.15 episodes per patient/year). Severe trauma secondary to syncope relapse occurred in 2% and mild trauma in 4% of the patients. CONCLUSION: A strategy based on early diagnostic ILR application, with therapy delayed until documentation of syncope allows a safe, specific, and effective therapy in patients with NMS.