Atrial fibrillation detection using a novel three-vector cardiac implantable monitor: the atrial fibrillation detect study.

AIMS: Continuous rhythm monitoring is valuable for adequate atrial fibrillation (AF) management in the clinical setting. Subcutaneous leadless implantable cardiac monitors (ICMs) yield an improved AF detection, overcoming the intrinsic limitations of the currently available external recording systems, thus resulting in a more accurate patient treatment. The study purpose was to assess the detection performance of a novel three-vector ICM device equipped with a dedicated AF algorithm. METHODS AND RESULTS: Sixty-six patients (86.4% males; mean age 60.4 ± 9.4 years) at risk to present AF episodes, having undergone the novel ICM implant (BioMonitor, Biotronik SE&Co. KG, Berlin, Germany), were enrolled. External 48-h ECG Holter was performed 4 weeks after the device implantation. The automatic ICM AF classification was compared with the manual Holter arrhythmia recordings. Of the overall study population, 63/66 (95.5%) had analysable Holter data, 39/63 (62%) showed at least one true AF episode. All these patients had at least one AF episode stored in the ICM. On Holter monitoring, 24/63 (38%) patients did not show AF episodes, in 16 of them (16/24, 67%), the ICM confirmed the absence of AF. The AF detection sensitivity and positive predictive value for episodes' analysis were 95.4 and 76.3%, respectively. CONCLUSION: Continuous monitoring using this novel device, equipped with a dedicated detection algorithm, yields an accurate and reliable detection of AF episodes. The ICM is a promising tool for tailoring individual AF patient management. Further long-term prospective studies are necessary to confirm these encouraging results.

Improving cardiac resynchronization therapy response with multipoint left ventricular pacing: Twelve-month follow-up study.

BACKGROUND: Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint™ Pacing [MPP], St. Jude Medical) improves acute LV function and LV reverse remodeling at 3 months. OBJECTIVE: The purpose of this study was to test the hypothesis that MPP can also improve LV function at 12 months. METHODS: Consecutive patients receiving a CRT implant (Unify Quadra MP™ or Quadra Assura MP™ CRT-D and Quartet™ LV lead, St. Jude Medical) were randomized to receive pressure-volume (PV) loop optimized biventricular pacing with either conventional cardiac resynchronization therapy (CONV) or MPP. CRT response was defined by a reduction in end-systolic volume (ESV) ≥15% relative to BASELINE as determined by a blinded observer and alive status. RESULTS: Forty-four patients (New York Heart Association class III, ejection fraction [EF] 29% ± 6%, QRS 152 ± 17 ms) were enrolled and randomized to either CONV (N = 22) or MPP (N = 22). During the observation period, 2 patients died of noncardiac causes and 2 patients were lost to follow-up. After 12 months, 12 of 21 patients (57%) in the CONV group and 16 of 21 patients (76%) in the MPP group were classified as CRT responders (P = .33). ESV reduction and EF increase relative to BASELINE were significantly greater with MPP than with CONV (ESV: median -25%, interquartile range [IQR] [-39% to -20%] vs median -18%, IQR [-25% to -2%], P = .03; EF: median +15%, IQR [8% to 20%] vs median +5%, IQR [-1% to 8%], P <.001). CONCLUSION: Sustaining the trend observed 3 months postimplant, PV loop-guided multipoint LV pacing resulted in greater LV reverse remodeling and increased LV function at 12 months compared to PV loop-guided conventional CRT.

Multipoint left ventricular pacing in a single coronary sinus branch improves mid-term echocardiographic and clinical response to cardiac resynchronization therapy.

INTRODUCTION: Cardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing in a single coronary sinus branch improves acute LV function. We hypothesized that multipoint pacing (MPP) can improve midterm echocardiographic and clinical response compared with conventional CRT. METHODS AND RESULTS: Consecutive patients receiving a CRT implant (Unify Quadra MP™ or Quadra Assura MP™ CRT-D and Quartet™ LV lead, St. Jude Medical, Sylmar, CA, USA) were randomized to receive biventricular (BiV) pacing with either conventional LV pacing (CONV group) or MPP (MPP group). For each patient, an optimal pacing configuration for the assigned pacing mode was programmed based on intraoperative pressure-volume (PV) loop measurements. A clinical evaluation and transthoracic echocardiogram were performed before implant (BASELINE) and at 3 months postimplant and analyzed by a blinded observer. A reduction in end-systolic volume (ESV) of ≥15% relative to BASELINE was prospectively defined as response to CRT. Forty-four patients (NYHA Class III, EF 29 ± 6%, QRS duration 152 ± 17 milliseconds) were enrolled and randomized. One patient in the MPP group was lost to follow-up and excluded from further analysis. After 3 months, 11 of 22 (50%) CONV patients and 16 of 21 (76%) MPP patients were classified as responders. ESV reduction, EF increase, and NYHA class reduction relative to BASELINE were significantly greater in the MPP group than in the CONV group (ESV: -21.0 ± 13.9 vs. -12.6 ± 11.1%, P = 0.03; EF: +9.8 ± 5.1 vs. +2.0 ± 7.8 percentage points, P < 0.001; ΔNYHA: -1.05 ± 0.22 vs. -0.72 ± 0.46 functional classes, P = 0.006). CONCLUSION: PV loop optimized BiV pacing with MPP resulted in an improved rate of response to CRT.

Wolff-Parkinson-White syndrome in the era of catheter ablation: insights from a registry study of 2169 patients.

BACKGROUND: The management of Wolff-Parkinson-White is based on the distinction between asymptomatic and symptomatic presentations, but evidence is limited in the asymptomatic population. METHODS AND RESULTS: The Wolff-Parkinson-White registry was an 8-year prospective study of either symptomatic or asymptomatic Wolff-Parkinson-White patients referred to our Arrhythmology Department for evaluation or ablation. Inclusion criteria were a baseline electrophysiological testing with or without radiofrequency catheter ablation (RFA). Primary end points were the percentage of patients who experienced ventricular fibrillation (VF) or potentially malignant arrhythmias and risk factors. Among 2169 enrolled patients, 1001 (550 asymptomatic) did not undergo RFA (no-RFA group) and 1168 (206 asymptomatic) underwent ablation (RFA group). There were no differences in clinical and electrophysiological characteristics between the 2 groups except for symptoms. In the no-RFA group, VF occurred in 1.5% of patients, virtually exclusively (13 of 15) in children (median age, 11 years), and was associated with a short accessory pathway antegrade refractory period (P<0.001) and atrioventricular reentrant tachycardia initiating atrial fibrillation (P<0.001) but not symptoms. In the RFA group, ablation was successful in 98.5%, and after RFA, no patients developed malignant arrhythmias or VF over the 8-year follow-up. Untreated patients were more likely to experience malignant arrhythmias and VF (log-rank P<0.001). Time-dependent receiver-operating characteristic curves for predicting VF identified an optimal anterograde effective refractory period of the accessory pathway cutoff of 240 milliseconds. CONCLUSIONS: The prognosis of the Wolff-Parkinson-White syndrome essentially depends on intrinsic electrophysiological properties of AP rather than on symptoms. RFA performed during the same procedure after electrophysiological testing is of benefit in improving the long-term outcomes.

Multipoint left ventricular pacing improves acute hemodynamic response assessed with pressure-volume loops in cardiac resynchronization therapy patients.

BACKGROUND: Conventional cardiac resynchronization therapy (CRT) improves acute cardiac hemodynamics. OBJECTIVE: To investigate if CRT with multipoint left ventricular (LV) pacing in a single coronary sinus branch (MultiPoint Pacing [MPP], St Jude Medical, Sylmar, CA) can offer further hemodynamic benefits to patients. METHODS: Forty-four consecutive patients (80% men, New York Heart Association III, end-systolic volume 180 ± 77 mL, ejection fraction 27% ± 6%, and QRS duration 152 ± 17 ms) receiving a CRT device implant (Unify Quadra MP or Quadra Assura MP and Quartet LV lead, St Jude Medical) underwent intraoperative assessment of LV hemodynamics by using a pressure-volume loop system (Inca, CD Leycom). A pacing protocol was performed, including 9 biventricular pacing interventions with conventional CRT (CONV) using distal and proximal LV electrodes and various MPP configurations. Each pacing intervention was performed twice in randomized order with right ventricular pacing (BASELINE) repeated after every intervention. RESULTS: Evaluable recordings were obtained in 42 patients. Relative to BASELINE, the best MPP intervention significantly increased the rate of pressure change (dP/dtmax; 15.9% ± 10.0% vs 13.5% ± 8.8%; P < .001), stroke work (27.2% ± 42.5% vs 19.4% ± 32.2%; P = .018), stroke volume (10.4% ± 22.5% vs 4.1% ± 13.1%; P = .003), and ejection fraction (10.5% ± 20.9% vs 5.3% ± 13.2%; P = .003) as compared with the best CONV intervention. Moreover, the best MPP intervention improved acute diastolic function, significantly decreasing -dP/dtmin (-13.5% ± 10.2% vs -10.6% ± 6.8%; P = .011), relaxation time constant (-7.5% ± 9.0% vs -4.8% ± 7.2%; P = .012), and end-diastolic pressure (-18.2% ± 22.4% vs -8.7% ± 21.4%; P < .001) as compared with the best CONV intervention. CONCLUSIONS: CRT with MPP can significantly improve acute LV hemodynamic parameters assessed with pressure-volume loop measurements as compared with CONV.

Risk of malignant arrhythmias in initially symptomatic patients with Wolff-Parkinson-White syndrome: results of a prospective long-term electrophysiological follow-up study.

BACKGROUND: The available amount of detailed long-term data in patients with Wolff-Parkinson-White syndrome is limited, and no prospective electrophysiological studies looking at predictors of malignant arrhythmia are available. METHODS AND RESULTS: Among 8575 symptomatic Wolff-Parkinson-White patients with atrioventricular reentrant tachycardia referred for electrophysiological test, 369 (mean age, 23±12.5 years) declined catheter ablation and were followed up. The primary end point of the study was to evaluate over a 5-year follow-up the predictors and characteristics of patients who develop malignant arrhythmias. After a mean follow-up of 42.1±10 months, malignant arrhythmias developed in 29 patients (mean age, 13.9±5.6 years; 26 male), resulting in presyncope/syncope (25 patients), hemodynamic collapse (3 patients), or cardiac arrest caused by ventricular fibrillation (1 patient). Of the remaining 340 patients, 168 (mean age, 34.2±9.0 years) remained asymptomatic up to 5 years, and 172 (mean age, 13.6±5.1 years) had benign recurrence, including sustained atrioventricular reentrant tachycardia (132 patients) or atrial fibrillation (40 patients). Compared with the group with no malignant arrhythmias, the group with malignant arrhythmias showed shorter accessory-pathway effective refractory period (P<0.001) and more often exhibited multiple accessory pathways (P<0.001), and atrioventricular reentrant tachycardia triggering sustained pre-excited atrial fibrillation was more frequently inducible (P<0.001). Multivariable analysis demonstrated that short accessory-pathway effective refractory period (P<0.001) and atrioventricular reentrant tachycardia triggering sustained pre-excited atrial fibrillation (P<0.001) were independent predictors of malignant arrhythmias. CONCLUSIONS: Symptomatic patients with Wolff-Parkinson-White syndrome generally have a good outcome, and predictors of malignant arrhythmias are similar to those reported for asymptomatic patients with ventricular pre-excitation.

Irrigated-tip magnetic catheter ablation of AF: a long-term prospective study in 130 patients.

BACKGROUND: Nonirrigated magnetic ablation may result in potential char, ineffective lesions, and longer procedure times. OBJECTIVE: This study sought to report the safety and long-term efficacy of irrigated-tip magnetic ablation of atrial fibrillation (AF). METHODS: Catheter ablation was remotely performed using a new irrigated-tip magnetic catheter (ThermoCool NaviStar-RMT, Biosense Webster, Diamond Bar, CA) in 130 consecutive patients (mean age 59.7 ± 10.5 years) with symptomatic paroxysmal (81 patients) or persistent (49 patients) AF. The radiofrequency (RF) generator was set to fixed power of 30 W. The primary end point of the study was freedom from atrial tachycardia (AT)/AF off antiarrhythmic drugs. RESULTS: The procedure was safely performed in all conventional ablation targets, but crossover to manual catheters was required in 12 patients to complete the mitral isthmus line. The total procedure time was 94.6 ± 15.3 minutes. Impedance values significantly decreased during RF applications (P < .001) and the maximum temperature on the catheter tip was 36.4°C ± 0.8°C. The follow-up duration was 15.3 ± 4.9 months. The primary end point was achieved in 66 of 81(81.4%) patients with paroxysmal AF and in 33 of 49 (67.3%) with persistent AF (P = .035, by log-rank test). Patients with paroxysmal AF had higher late AF recurrence (P =.044). Overall, postablation incessant left AT developed in 7 of 130 (5.4%) patients. Major complications were not observed. Left atrial diameter (P < .001) and heart failure (P = .032) predicted arrhythmia recurrence after remote irrigated-tip ablation. CONCLUSION: Remote ablation with irrigated-tip magnetic catheters can be safely and effectively performed in patients with AF, but longer follow-up periods are required to evaluate late AF recurrences.

Asymptomatic ventricular preexcitation: a long-term prospective follow-up study of 293 adult patients.

BACKGROUND: Sudden cardiac death can be the first clinical presentation of asymptomatic ventricular preexcitation. METHODS AND RESULTS: From 1995 to 2005, we prospectively collected clinical and electrophysiological data among 293 adults with asymptomatic ventricular preexcitation (61.4% males; median age, 36 years; interquartile range [IQR], 28 to 47.5). After electrophysiological testing, patients were prospectively followed, taking no drugs. The primary end point of the study was the occurrence of a first arrhythmic event. Predictors of arrhythmic events were analyzed by univariate and multivariate Cox models. Over a median follow-up of 67 months (minimum to maximum, 8 to 90), after electrophysiological testing, 262 patients (median age, 37 years; IQR, 30 to 48) did not experience arrhythmic events, remaining totally asymptomatic, whereas 31 patients (median age, 25 years; IQR, 22 to 29; median follow-up, 27 months; minimum to maximum, 8 to 55) had a first arrhythmic event, which was potentially life-threatening in 17 of them (median age, 24 years; IQR, 20 to 28.5; median follow-up, 25 months; minimum to maximum, 9 to 55). Potentially life-threatening tachyarrhythmias resulted in resuscitated cardiac arrest (1 patient), presyncope (7 patients) syncope (4 patients), or dizziness (5 patients). In multivariate analysis age (P=0.004), inducibility (P=0.001) and anterograde effective refractory period of the accessory pathway < or = 250 ms (P=0.001) predicted potentially life-threatening arrhythmias. CONCLUSIONS: These results indicate that prognosis of adults who present with asymptomatic ventricular preexcitation is good, and the risk of a significant event is small. Short anterograde effective refractory period of the accessory pathway and inducibility at baseline are independent predictors of potentially life-threatening arrhythmic events, and the risk decreases with increasing age.

New-onset atrial fibrillation as first clinical manifestation of latent Brugada syndrome: prevalence and clinical significance.

AIMS: To evaluate the prevalence, clinical significance, and prognosis of latent Brugada syndrome (BrS) in patients with new-onset atrial fibrillation (AF) unmasked by class 1C antiarrhythmic drugs. METHODS AND RESULTS: Between January 2000 and June 2008, all consecutive patients with new-onset AF, who after flecainide exhibited typical Brugada ECG pattern, underwent electrophysiologic, pharmacologic, and genetic testing. Among 346 patients [median age 53 years; interquartile range (IQR), 15], 11 (3.2%; median age 51 years; IQR, 19) diagnosed as lone AF exhibited typical Brugada ECG pattern. Genetic testing was negative. Ventricular tachycardia/ventricular fibrillation (VT/VF) was induced by electrophysiologic testing (five patients) or during flecainide infusion (one patient). Six patients with type 1 ECG pattern and inducible VT/VF underwent ICD implantation. During a median follow-up of 31.5 months (range: 10-85) after ICD implantation, three patients developed BrS and one of them experienced VF. Patients without ICD (five patients) remained asymptomatic during a median follow-up of 74 months. Persistent type 1 pattern occurred only in the three patients who developed BrS. CONCLUSION: This study, for the first time, reveals the prevalence of latent BrS in patients with new-onset lone AF, which may precede VT/VF. Persistence of type 1 and ventricular tachyarrhythmias inducibility represents a marker of electrical instability leading to sudden death.