Etiological diagnosis, prognostic significance and role of electrophysiological study in patients with Brugada ECG and syncope.

BACKGROUND: Syncope is considered a risk factor for life-threatening arrhythmias in Brugada patients. Distinguishing a benign syncope from one due to ventricular arrhythmias is often difficult, unless an ECG is recorded during the episode. Aim of the study was to analyze the characteristics of syncopal episodes in a large population of Brugada patients and evaluate the role of electrophysiological study (EPS) and the prognosis in the different subgroups. METHODS AND RESULTS: One hundred ninety-five Brugada patients with history of syncope were considered. Syncope were classified as neurally mediated (group 1, 61%) or unexplained (group 2, 39%) on the basis of personal and family history, clinical features, triggers, situations, associated signs, concomitant therapy. Most patients underwent EPS; they received ICD or implantable loop-recorder on the basis of the result of investigations and physician's judgment. At 62±45months of mean follow-up, group 1 showed a significantly lower incidence of arrhythmic events (2%) as compared to group 2 (9%, p<0.001). Group 2 patients with positive EPS showed the highest risk of arrhythmic events (27%). No ventricular events occurred in subjects with negative EPS. CONCLUSION: Etiological definition of syncope in Brugada patients is important, as it allows identifying two groups with different outcome. Patients with unexplained syncope and ventricular fibrillation induced at EPS have the highest risk of arrhythmic events. Patients presenting with neurally mediated syncope showed a prognosis similar to that of the asymptomatic and the role of EPS in this group is unproven.

Automatic atrial capture device control in real-life practice: A multicenter experience.

BACKGROUND: Device-based fully automatic pacing capture detection is useful in clinical practice and important in the era of remote care management. The main objective of this study was to verify the effectiveness of the new ACAP Confirm® algorithm in managing atrial capture in the medium term in comparison with early post-implantation testing. METHODS: Data were collected from 318 patients (66% male; mean age, 73±10 years); 237 of these patients underwent device implantation and 81 box changes in 31 Italian hospitals. Atrial threshold measurements were taken manually and automatically at different pulse widths before discharge and during follow-up (7±2 months) examination. RESULTS: The algorithm worked as expected in 73% of cases, considering all performed tests. The success rate was 65% and 88% pre-discharge and during follow-up examination (p<0.001), respectively, in patients who had undergone implantation. We did not detect any difference in the performance of the algorithm as a result of the type of atrial lead used. The success rate was 70% during pre-discharge testing in patients undergoing device replacement. Considering all examination types, manual and automatic measurements yielded threshold values of 1.07±0.47 V and 1.03±0.47 V at 0.2-ms pulse duration (p=0.37); 0.66±0.37 V and 0.67±0.36 V at 0.4 ms (p=0.42); and 0.5±0.28 V and 0.5±0.29 V at 1 ms (p=0.32). CONCLUSIONS: The results show that the algorithm works before discharge, and its reliability increases over the medium term. The algorithm also proved accurate in detecting the atrial threshold automatically. The possibility of activating it does not seem to be influenced by the lead type used, but by the time from implantation.

Characterization of ventricular activation pattern and acute hemodynamics during multipoint left ventricular pacing.

BACKGROUND: Multipoint left ventricular (LV) pacing (MultiPoint Pacing [MPP], St Jude Medical, Sylmar, CA) in a single coronary sinus branch has been introduced as a novel means of cardiac resynchronization therapy (CRT). It is speculated that MPP improves LV function by capturing a larger LV tissue area, resulting in uniform wavefront propagation throughout the ventricles, in comparison to conventional biventricular pacing (BIV). OBJECTIVE: The purpose of this study was to evaluate MPP by means of contact mapping and hemodynamic measures to understand the underlying mechanisms and effects. METHODS: Ten patients with non-ischemic cardiomyopathy (mean age 69 ± 9 years; 6 men (60%); New York Heart Association heart failure class II or III; QRS duration 173 ± 20 ms; LV ejection fraction 27% ± 5%) received a CRT-defibrillator capable of MPP. After the implantation procedure, an acute pacing protocol was implemented, including 2 BIV and up to 9 MPP interventions. In all pacing interventions, LV electrical activation patterns and hemodynamics (dP/dtmax) were evaluated, and for each patient, both the resulting measures were compared between MPP and BIV interventions. RESULTS: Compared with BIV, MPP resulted in an increase in LV dP/dtmax (30% ± 13% vs. 25% ± 11%; P = .041), a reduction in QRS duration (22% ± 11% vs. 11% ± 11%; P = .01), and a decrease in total endocardial activation time (25% ± 15% vs. 10% ± 20%; P = .01). MPP resulted in a larger capture of LV mass during the first 25 ms (35% ± 22% vs. 16% ± 8%; P = .005) and during the first 50 ms (78% ± 27% vs. 60% ± 23%; P = .03) of pacing, suggesting a quicker wavefront propagation throughout the left ventricle. CONCLUSION: In this acute study, MPP in CRT improved both endocardial and surface electrical parameters and hemodynamics in comparison with BIV.

Single-center experience of a quadripolar pacing lead for cardiac resynchronization therapy.

AIM: Recent studies have shown that a quadripolar left ventricular (LV) lead can result in low rates of dislocation and phrenic nerve stimulation (PNS) acutely and on medium-term follow-up in cardiac resynchronization therapy (CRT). We evaluated the outcomes of CRT patients in whom a quadripolar LV lead was implanted in our institution. METHODS: We studied 45 consecutive heart failure patients (75 % men; age, 70.3 ± 9.0 years) following successful implantation of a quadripolar LV lead. Demographic and clinical data were collected preoperatively, and patients were followed up for 18.9 months. RESULTS: The implantation success rate was 100 %. Mean overall duration was 100.1 ± 34.6 min, and X-ray exposure time was 13.20 ± 13.5 min. The most distal effective pacing site was used as the final pacing configuration in all patients. Acute dislodgment requiring reoperation occurred before discharge in three cases (6.6 %). Six patients (13 %) suffered PNS during follow-up; we solved this problem by changing the stimulation vector. Three months after implantation, a mean of six out of ten effective sites (threshold <2.5 V at 1.5 ms, no PNS) per patient was recorded. CONCLUSIONS: Over the relatively long term, the quadripolar LV lead was associated with excellent pacing thresholds and low rates of dislocation and PNS.

Risk stratification in Brugada syndrome: results of the PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) registry.

OBJECTIVES: The PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) prospective registry was designed to assess the predictive accuracy of sustained ventricular tachycardia/ventricular fibrillation (VTs/VF) inducibility and to identify additional predictors of arrhythmic events in Brugada syndrome patients without history of VT/VF. BACKGROUND: Brugada syndrome is a genetic disease associated with increased risk of sudden cardiac death. Even though its value has been questioned, inducibility of VTs/VF is widely used to select candidates to receive a prophylactic implantable defibrillator, and its accuracy has never been addressed in prospective studies with homogeneous enrolling criteria. METHODS: Patients with a spontaneous or drug-induced type I electrocardiogram (ECG) and without history of cardiac arrest were enrolled. The registry included 308 consecutive individuals (247 men, 80%; median age 44 years, range 18 to 72 years). Programmed electrical stimulation was performed at enrollment, and patients were followed-up every 6 months. RESULTS: During a median follow-up of 34 months, 14 arrhythmic events (4.5%) occurred (13 appropriate shocks of the implantable defibrillator, and 1 cardiac arrest). Programmed electrical stimulation performed with a uniform and pre-specified protocol induced ventricular tachyarrhythmias in 40% of patients: arrhythmia inducibility was not a predictor of events at follow-up (9 of 14 events occurred in noninducible patients). History of syncope and spontaneous type I ECG (hazard ratio [HR]: 4.20), ventricular refractory period <200 ms (HR: 3.91), and QRS fragmentation (HR: 4.94) were significant predictors of arrhythmias. CONCLUSIONS: Our data show that VT/VF inducibility is unable to identify high-risk patients, whereas the presence of a spontaneous type I ECG, history of syncope, ventricular effective refractory period <200 ms, and QRS fragmentation seem useful to identify candidates for prophylactic implantable cardioverter defibrillator.

Risk stratification of the patients with Brugada type electrocardiogram: a community-based prospective study.

AIMS: Risk stratification of patients with Brugada electrocardiogram (ECG) is being strongly debated. Conflicting results have been suggested from international registries, which enrolled non-consecutive cases, studied with different programmed electrical stimulation (PES) protocols. The aim of this study was to prospectively evaluate the incidence of arrhythmic events and the prognostic role of clinical presentation, ECG, and of a standardized PES protocol in consecutive cases from a community-based population. METHODS AND RESULTS: A total of 166 consecutive patients (45 +/- 14 years) with Brugada ECG were enrolled. Type 1 ECG was observed spontaneously in 72 (43%) and after pharmacological testing in 94 (57%). One hundred and three (62%) were asymptomatic, 58 (35%) had syncope, and five (3%) had a prior cardiac arrest. One hundred and thirty-five (81%) underwent PES with two extra stimuli up to ventricular refractoriness and 34% had ventricular fibrillation (VF) induced. Arrhythmic events occurred in nine patients at a mean follow-up of 30 +/- 21 months (2.2 events per 100 person-year): in three (60%) patients with aborted sudden death (aSD), five (8.6%) of those with syncope, and one (1%) of the asymptomatic. The only predictors of events were a history of syncope or aSD (P = 0.02) and induction at PES (P = 0.004). CONCLUSION: Clinical presentation is the most important parameter in the risk stratification of patients with Brugada ECG. Programmed electrical stimulation seems valuable, particularly in patients with previous syncope.

Cardiac resynchronization therapy modifies the neurohormonal profile, hemodynamic and functional capacity in heart failure patients.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been shown to improve the clinical status and survival in congestive heart failure (CHF) patients, but little is known about its influence on neurohormonal profile. METHODS: Heart failure patients treated with CRT for moderate/severe heart failure were studied with echocardiography, cardiopulmonary test, and neurohormonal profile [brain natriuretic peptide (BNP), endothelin (END), big endothelin (big-END), epinephrine (EPI), tumor necrosis factor-alpha (TNF-alpha)] at baseline and after 1 year from the pacemaker implantation. RESULTS: 120 NYHA II-IV patients entered this study, all with an indication to CRT; 100 agreed to be implanted (group A), whereas 20 refused, identifying a control group (group B). In group A NYHA class (from 3.15+/-0.49-1.15+/-0.49, p=0.001), left ventricular ejection fraction (from 19.6+/-4.95-35.6+/-5.95%, p=0.001), severity of mitral regurgitation (from 13.3+/-4.19-6.09+/-4.11 cmq, p=0.001), and peak VO(2) (from 9.68+/-4.61-13.35+/-3.32 mL/kg/min, p=0.001) improved at 1-year follow-up. In the neurohormonal profile only plasma BNP (from 185.1+/-185.9-110.2+/-137.5 pg/mL, p=0.03) and big-END (from 1.8+/-1.5-0.87+/-0.7 fmol/mL, p=0.007) were reduced significantly. None of these parameters significantly changed in the control group at 1-year follow-up. CONCLUSIONS: In patients with moderate/severe heart failure, CRT improved clinical status and the functional parameters modifying the neurohormonal profile at 1-year follow-up.