Electrical storm treatment by percutaneous stellate ganglion block: the STAR study.

BACKGROUND AND AIMS: An electrical storm (ES) is a clinical emergency with a paucity of established treatment options. Despite initial encouraging reports about the safety and effectiveness of percutaneous stellate ganglion block (PSGB), many questions remained unsettled and evidence from a prospective multicentre study was still lacking. For these purposes, the STAR study was designed. METHODS: This is a multicentre observational study enrolling patients suffering from an ES refractory to standard treatment from 1 July 2017 to 30 June 2023. The primary outcome was the reduction of treated arrhythmic events by at least 50% comparing the 12 h following PSGB with the 12 h before the procedure. STAR operators were specifically trained to both the anterior anatomical and the lateral ultrasound-guided approach. RESULTS: A total of 131 patients from 19 centres were enrolled and underwent 184 PSGBs. Patients were mainly male (83.2%) with a median age of 68 (63.8-69.2) years and a depressed left ventricular ejection fraction (25.0 ± 12.3%). The primary outcome was reached in 92% of patients, and the median reduction of arrhythmic episodes between 12 h before and after PSGB was 100% (interquartile range -100% to -92.3%). Arrhythmic episodes requiring treatment were significantly reduced comparing 12 h before the first PSGB with 12 h after the last procedure [six (3-15.8) vs. 0 (0-1), P < .0001] and comparing 1 h before with 1 h after each procedure [2 (0-6) vs. 0 (0-0), P < .001]. One major complication occurred (0.5%). CONCLUSIONS: The findings of this large, prospective, multicentre study provide evidence in favour of the effectiveness and safety of PSGB for the treatment of refractory ES.

Voltage and propagation mapping: New tools to improve successful ablation of atrioventricular nodal reentry tachycardia.

INTRODUCTION: Mapping system is useful in ablation of atrioventricular nodal reentry tachycardia (AVNRT) and localization of anatomic variances. Voltage mapping identifies a low voltage area in the Koch triangle called low-voltage-bridge (LVB); propagation mapping identifies the collision point (CP) of atrial wavefront convergence. We conducted a prospective study to evaluate the relationship between LVB and CP with successful site of ablation and identify standard value for LVB. MATERIALS AND METHODS: Three-dimensional (3D) maps of the right atria were constructed from intracardiac recordings using the ablation catheter. Cut-off values on voltage map were adjusted until LVB was observed. On propagation map, atrial wavefronts during sinus rhythm collide in the site representing CP, indicating the area of slow pathway conduction. Ablation site was selected targeting LVB and CP site, confirmed by anatomic position on fluoroscopy and atrioventricular ratio. RESULTS: Twenty-seven consecutive patients were included. LVB and CP were present in all patients. Postprocedural evaluation identified standard cut-off of 0.3-1 mV useful for LVB identification. An overlap between LVB and CP was observed in 23 (85%) patients. Procedure success was achieved in all patient with effective site at first application in 22 (81%) patients. There was a significant correlation between LVB, CP, and the site of effective ablation (p = .001). CONCLUSION: We found correlation between LVB and CP with the site of effective ablation, identifying a voltage range useful for standardized LVB identification. These techniques could be useful to identify ablation site and minimize radiation exposure.

Closed loop stimulation in left bundle branch area pacing.

INTRODUCTION: Closed Loop Stimulation (CLS) is a rate-responsive algorithm that adjusts heart rate (HR) based on changes in intracardiac impedance measured from the right ventricle lead. However, the use of CLS in conduction system pacing has not been investigated. In this retrospective study, we aimed to assess whether CLS with left bundle branch area pacing (LBBAP) can generate an appropriate distribution of HR in daily life. METHODS AND RESULTS: Our study included 24 patients with CLS pacing and chronotropic incompetence, comparing them with 19 patients receiving DDD pacing, all with LBBAP. Cumulative HR distribution charts were generated using data from a single device interrogation with a minimum follow-up period of 30 days. In DDD-CLS mode, there was a higher percentage of atrial pacing compared to DDD mode (median 58% [interquartile range 29%-83%] vs. 13% [10%-26%], p = .001), and CLS-paced beats were present across all frequency bins. The distribution of beats between the groups was similar (p = .643), resulting in comparable mean HR (72 bpm [70-77] vs. 73 bpm [65-75], p = .615). CONCLUSIONS: In the context of LBBAP, CLS effectively modulates pacing rates over a wide frequency range. This lead position does not adversely affect the rate-responsive performance of the algorithm.

Optimization of the atrioventricular delay in conduction system pacing.

INTRODUCTION: In patients receiving conduction system pacing (CSP), it is not well established how to program the sensed atrioventricular delay (sAVD), with respect to the type of capture obtained (selective, nonselective His-bundle [HB] capture or left bundle branch [LBB] capture). The aim of this study was to acutely assess the effectiveness of an electrophysiology (EP)-guided method for sAVD optimization by comparing it with the echocardiogram-guided optimization. METHODS AND RESULTS: Consecutive patients undergoing HB or LBB pacing were enrolled. The EP-guided sAVD was defined as the sAVD leading to a PR interval of 150 ms on surface electrocardiogram (ECG). In HB pacing patients, EP-guided sAVD was obtained subtracting the time from the onset of the P wave on ECG to the local atrial electrogram (EGM) recorded by the atrial lead (right atrial sensing latency, RASL) and the His-ventricular interval from 150 ms; in LBB pacing patients, subtracting RASL from 150 ms. Transmitral flow assessment by pulsed wave Doppler was used to find the echo-optimized sAVD by a modified iterative method. The discordance between the EP-guided and the echo-optimized sAVD was recorded. RESULTS: Seventy-one patients were enrolled: 12 with selective, 32 nonselective HB capture, and 27 LBB capture. Overall, the rate of concordance between the EP-guided and the echo-optimized sAVD was 71.8%, with no significant differences between the three groups. CONCLUSION: In CSP patients, an optimal sAVD can be programmed, in more than 70% of cases, considering only simple EGM intervals to obtain a physiological PR interval on surface ECG.

Incidence of ventricular arrhythmias related to COVID infection and vaccination in patients with Brugada syndrome: Insights from a large Italian multicenter registry based on continuous rhythm monitoring.

INTRODUCTION: Brugada syndrome (BrS) has a dynamic ECG pattern that might be revealed by certain conditions such as fever. We evaluated the incidence and management of ventricular arrhythmias (VAs) related to COVID-19 infection and vaccination among BrS patients carriers of an implantable loop recorder (ILR) or implantable cardioverter-defibrillator (ICD) and followed by remote monitoring. METHODS: This was a multicenter retrospective study. Patients were carriers of devices with remote monitoring follow-up. We recorded VAs 6 months before COVID-19 infection or vaccination, during infection, at each vaccination, and up to 6-month post-COVID-19 or 1 month after the last vaccination. In ICD carriers, we documented any device intervention. RESULTS: We included 326 patients, 202 with an ICD and 124 with an ILR. One hundred and nine patients (33.4%) had COVID-19, 55% of whom developed fever. Hospitalization rate due to COVID-19 infection was 2.76%. After infection, we recorded only two ventricular tachycardias (VTs). After the first, second, and third vaccines, the incidence of non-sustained ventricular tachycardia (NSVT) was 1.5%, 2%, and 1%, respectively. The incidence of VT was 1% after the second dose. Six-month post-COVID-19 healing or 1 month after the last vaccine, we documented NSVT in 3.4%, VT in 0.5%, and ventricular fibrillation in 0.5% of patients. Overall, one patient received anti-tachycardia pacing and one a shock. ILR carriers had no VAs. No differences were found in VT before and after infection and before and after each vaccination. CONCLUSIONS: From this large multicenter study conducted in BrS patients, followed by remote monitoring, the overall incidence of sustained VAs after COVID-19 infection and vaccination is relatively low.

The PhysioVP-AF study, a randomized controlled trial to assess the clinical benefit of physiological ventricular pacing vs. managed ventricular pacing for persistent atrial fibrillation prevention in patients with prolonged atrioventricular conduction: design and rationale.

AIMS: In patients with prolonged atrioventricular (AV) conduction and pacemaker (PM) indication due to sinus node disease (SND) or intermittent AV-block who do not need continuous ventricular pacing (VP), it may be difficult to determine which strategy to adopt. Currently, the standard of care is to minimize unnecessary VP by specific VP avoidance (VPA) algorithms. The superiority of this strategy over standard DDD or DDD rate-responsive (DDD/DDDR) in improving clinical outcomes is controversial, probably owing to the prolongation of the atrialventricular conduction (PR interval) caused by the algorithms. Conduction system pacing (CSP) may offer the most physiological-VP approach, providing appropriate AV conduction and preventing pacing-induced dyssynchrony. METHODS AND RESULTS: PhysioVP-AF is a prospective, controlled, randomized, single-blind trial designed to determine whether atrial-synchronized conduction system pacing (DDD-CSP) is superior to standard DDD-VPA pacing in terms of 3-year reduction of persistent-AF occurrence. Cardiovascular hospitalization, quality-of-life, and safety will be evaluated. Patients with indication for permanent DDD pacing for SND or intermittent AV-block and prolonged AV conduction (PR interval > 180 ms) will be randomized (1:1 ratio) to DDD-VPA (VPA-algorithms ON, septal/apex position) or to DDD-CSP (His bundle or left bundle branch area pacing, AV-delay setting to control PR interval, VPA-algorithms OFF). Approximately 400 patients will be randomized in 24 months in 13 Italian centres. CONCLUSION: The PhysioVP-AF study will provide an essential contribution to patient management with prolonged AV conduction and PM indication for sinus nodal disease or paroxysmal 2nd-degree AV-block by determining whether CSP combined with a controlled PR interval is superior to standard management that minimizes unnecessary VP in terms of reducing clinical outcomes.

Left bundle branch area pacing (LBBAP) Auto Threshold algorithms Evaluation for Conduction System Pacing: The LATECS pilot Trial.

BACKGROUND: Automated threshold measurements (ATM) and output adaptation improved safety and follow-up of cardiac implantable devices (CIED) in the last years. These algorithms were validated for conventional cardiac pacing; however, they were not suitable for permanent His Pacing. Left bundle branch area pacing (LBBAP) is an emerging technique to obtain physiologic cardiac stimulation; we tried to assess if ATM could be applied to this setting. METHODS: Consecutive patients receiving ATM-capable CIED and LBBAP in our hospital were enrolled in this prospective, observational trial; they were evaluated 3 months after implant, comparing pacing thresholds manually assessed and obtained via ATM. Subsequent remote follow-up was carried on when available. RESULTS: Forty-five patients were enrolled. ATM for LBBAP lead provided consistent results in all the patients and was therefore activated; mean value of manually obtained LBBAP capture threshold was 0.66 ± 0.19 V versus ATM of 0.64 ± 0.19 V. TOST analysis showed equivalence of the two measures (p = .66). At subsequent follow-up (mean follow up 7.7 ± 3.2 months), ATM was effective in assessing pacing thresholds and no clinical adverse event was observed. CONCLUSIONS: ATM algorithms proved equivalent to manual testing in determining capture threshold and were reliably employed in patients receiving LBBAP CIED.

Ablate and pace: Comparison of outcomes between conduction system pacing and biventricular pacing.

BACKGROUND: Conduction system pacing (CSP), including His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP), have been proposed as alternatives to biventricular pacing (BVP) in patients scheduled for ablate and pace (A&P) strategy. The aim of this study was to compare the clinical outcomes, including the rate and nature of device-related complications, between BVP and CSP in a cohort of patients undergoing A&P. METHODS: Prospective, multicenter, observational study, enrolling consecutive patients undergoing A&P. The risk of device-related complications and of heart failure (HF) hospitalization was prospectively assessed. RESULTS: A total of 373 patients (75.3 ± 8.7 years, 53.9% male, 68.9% with NYHA class ≥III) were enrolled: 263 with BVP, 68 with HBP, and 42 with LBBAP. Baseline characteristics of the three groups were similar. Compared to BVP and HBP, LBBAP was associated with the shortest mean procedural and fluoroscopy times and with the lowest acute capture thresholds (all p < .05). At 12-month follow-up LBBAP maintained the lowest capture thresholds and showed the longest estimated residual battery longevity (all p < .05). At 12-months follow-up the three study groups showed a similar risk of device-related complications (5.7%, 4.4%, and 2.4% for BVP, HBP, and LBBAP, respectively; p = .650), and of HF hospitalization (2.7%, 1.5%, and 2.4% for BVP, HBP, and LBBAP, respectively; p = .850). CONCLUSIONS: In the setting of A&P, CSP is a feasible pacing modality, with a midterm safety profile comparable to BVP. LBBAP offers the advantage of reducing procedural times and obtaining lower and stable capture thresholds, with a positive impact on the device longevity.

Impact of atrioventricular junction ablation and CRT-D on long-term mortality in patients with left ventricular dysfunction, permanent, refractory atrial fibrillation, and narrow QRS: Results of a propensity-matched analysis.

INTRODUCTION: In patients with symptomatic permanent atrial fibrillation (PEAF) and narrow QRS, atrio-ventricular junction ablation (AVJA) plus cardiac resynchronization therapy (CRT) is superior to medical therapy in reducing heart failure (HF) hospitalization and all-cause mortality. To compare the mortality of a population of patients with HF, reduced EF (rEF), and PEAF treated with AVJA plus CRT with that of a contemporary cohort of patients in sinus rhythm (SR) with similar baseline characteristics. METHODS AND RESULTS: In this prospective, multicentre, observational study, all-cause mortality in a group of consecutive patients undergoing AVJA and implantable cardioverter-defibrillator (ICD) combined with CRT implantation for HFrEF, narrow QRS, and PEAF with uncontrolled ventricular rate was compared with that of a contemporary cohort of patients in SR undergoing ICD implantation (not combined with CRT) for HFrEF and narrow QRS. Individual 1:1 propensity matching of baseline characteristics was performed. A total of 824 patients were enrolled. Propensity matching yielded 107 matched pairs. After a median follow-up of 52 months, all-cause mortality was similar in patients treated with AVJA plus CRT and in the control group (p = .434). In AVJA plus CRT patients, mortality was significantly lower than in control group patients with a history of paroxysmal/persistent AF (n = 45, p = .020), and similar to that of patients without a history of AF (n = 62, p = .459). CONCLUSIONS: After adjustment for patient characteristics, the long-term prognosis of patients with HFrEF, narrow QRS, and PEAF who underwent AVJA plus CRT was similar to that of a population of patients in SR with similar characteristics.

Rate and impact on patient outcome and healthcare utilization of complications requiring surgical revision: Subcutaneous versus transvenous implantable defibrillator therapy.

INTRODUCTION: Comparison data on management of device-related complications and their impact on patient outcome and healthcare utilization between subcutaneous implantable cardioverter-defibrillator (S-ICD) and transvenous ICD (TV-ICD) are lacking. We designed this prospective, multicentre, observational registry to compare the rate, nature, and impact of long-term device-related complications requiring surgical revision on patient outcome and healthcare utilization between patients undergoing S-ICD or TV-ICD implantation. METHODS AND RESULTS: A total of 1099 consecutive patients who underwent S-ICD or TV-ICD implantation were enrolled. Propensity matching for baseline characteristics yielded 169 matched pairs. Rate, nature, management, and impact on patient outcome of device-related complications were analyzed and compared between two groups. During a mean follow-up of 30 months, device-related complications requiring surgical revision were observed in 20 patients: 3 in S-ICD group (1.8%) and 17 in TV-ICD group (10.1%; p = .002). Compared with TV-ICD patients, S-ICD patients showed a significantly lower risk of lead-related complications (0% vs. 5.9%; p = .002) and a similar risk of pocket-related complications (0.6 vs. 2.4; p = .215) and device infection (0.6% vs. 1.2%; p = 1.000). Complications observed in S-ICD patients resulted in a significantly lower number of complications-related rehospitalizations (median 0 vs. 1; p = .013) and additional hospital treatment days (1.0 ± 1.0 vs. 6.5 ± 4.4 days; p = .048) compared with TV-ICD patients. CONCLUSIONS: Compared with TV-ICD, S-ICD is associated with a lower risk of complications, mainly due to a lower risk of lead-related complications. The management of S-ICD complications requires fewer and shorter rehospitalizations.

Effect of SAcubitril/Valsartan on left vEntricular ejection fraction and on the potential indication for Implantable Cardioverter Defibrillator in primary prevention: the SAVE-ICD study.

PURPOSE: Sacubitril/valsartan has been associated with a positive reverse left ventricular remodelling in patients with heart failure with reduced ejection fraction (HFrEF). These patients may also benefit from an ICD implant. We aimed to assess EF improvement after 6 months of treatment with sacubitril/valsartan, evaluating when ICD as primary prevention was no longer indicated. METHODS: Multicentre, observational, prospective study enrolling all consecutive patients with HFrEF and EF ≤ 35% with an ICD as primary prevention and starting treatment with sacubitril/valsartan (NCT03935087). Resynchronization therapy and patients experiencing appropriate ICD therapies before sacubitril/valsartan were excluded. RESULTS: Two-hundred-and-thirty patients were enrolled (73.9% males, mean age 64.3 ± 12.1 years) After 6 months of treatment, a reduction in left ventricular end-diastolic and end-systolic volumes was noted and LVEF increased from 28.3 ± 5.6% to 32.2 ± 6.5% (p < 0.001). At 6 months, a non-ischemic aetiology of cardiomyopathy and a final dose of sacubitril/valsartan > 24/26 mg twice daily were associated with a higher probability of an absolute increase of > 5% in LVEF. A total of 5.3% of primary prevention patients still had an arrhythmic event in the first 6 months after treatment with sacubitril/valsartan started. CONCLUSIONS: Sacubitril/valsartan improves systolic function in HFrEF, mainly due to reverse left ventricular remodelling. Improvement in EF after 6 months of treatment could help prevent ICD implantation in nearly one out of four patients, with important clinical and economic implications. However, the risk of sudden cardiac death in this recovered HFrEF population has not been thoroughly studied, and the present data should be interpreted only as hypothesis-generating.

Management of patients explanted for implantable cardioverter defibrillator infections: Bridge therapy with external temporary ICD.

AIMS AND METHODS: In case of cardiacimplantable electronicdevice (CIED)-related infections, it is mandatory to completely remove the device and administer prolonged antibiotic therapy. The management of patients explanted for an implantable defibrillator (ICD) infection is complex especially in patients needing anti-bradycardia pacing or tachyarrhythmia protection. We tested the efficacy and safety of a conventional ICD externally connected to a transvenous dual-coil lead as bridging therapy before the reimplant, comparing outcomes with a historical cohort of patients (N = 113) treated with temporary transvenous pacing. We enrolled 18 patients explanted for ICD infection and needing prolonged antibiotic therapy in three high-volume Italian centers. They received an external ICD stand-by for a mean of 16.5 (4-30) days before the reimplant. RESULTS: No patient experienced malfunction of the system, with a significant reduction of this complication versus temporary transfemoral pacing (37%, p = .004). Post-procedural occurrence of other complications (infection, relevant local bleeding, ventricular tachycardia during insertion of the lead, cardiac perforation, and venous thromboembolism) was low and not different in the two groups. One patient experienced an electrical storm, effectively recognized by the external ICD and treated with anti-tachycardia pacings (ATPs) and shocks. CONCLUSIONS: An approach with an external ICD seems to be a safe and viable option as bridging therapy in patients requiring ICD explant for CIED infection.

Risk of syncopal recurrences in patients treated with permanent pacing for bradyarrhythmic syncope: role of correlation between symptoms and electrocardiogram findings.

AIMS: To evaluate the risk of syncopal recurrences after pacemaker implantation in a population of patients with syncope of suspected bradyarrhythmic aetiology. METHODS AND RESULTS: Prospective, multicentre, observational registry enrolling 1364 consecutive patients undergoing pacemaker implantation for syncope of bradyarrhythmic aetiology (proven or presumed). Before pacemaker implantation, all patients underwent a cardiac work-up in order to establish the bradyarrhythmic aetiology of syncope. According to the results of the diagnostic work-up, patients were divided into three groups: Group A, patients in whom a syncope-electrocardiogram (ECG) correlation was established (n = 329, 24.1%); Group B, those in whom clinically significant bradyarrhythmias were detected without a documented syncope-ECG correlation (n = 877, 64.3%); and Group C, those in whom bradyarrhythmias were not detected and the bradyarrhythmic origin of syncope remained presumptive (n = 158, 11.6%). During a median follow-up of 50 months, 213 patients (15.6%) reported at least one syncopal recurrence. Patients in Groups B and C showed a significantly higher risk of syncopal recurrences than those in Group A [hazard ratios (HRs): 1.60 and 2.66, respectively, P < 0.05]. Failure to establish a syncope-ECG correlation during diagnostic work-up before pacemaker implantation was an independent predictor of syncopal recurrence on multivariate analysis (HR: 1.90; P = 0.002). CONCLUSION: In selecting patients with syncope of suspected bradyarrhythmic aetiology for pacemaker implantation, establishing a correlation between syncope and bradyarrhythmias maximizes the efficacy of pacing and reduces the risk of syncopal recurrences.

Cardiac resynchronization therapy and electrical storm: results of the OBSERVational registry on long-term outcome of ICD patients (OBSERVO-ICD).

Aims: Electrical storm (ES) is a condition defined as three or more episodes of ventricular fibrillation (VF) or ventricular tachycardia (VT) within 24 h, and usually coexist with advanced heart failure in patients with structural heart disease. The aim of the present study is to test whether cardiac resynchronization therapy (CRT) can be associated with a lower incidence of ES. Methods and results: The OBSERVO-ICD (NCT02735811) is a multicentre, retrospective registry, enrolling all consecutive patients undergoing ICD or CRT-D implantation from 2010 to 2012 in five Italian high-volume arrhythmia centres. Propensity score matching was used to compare two equally sized cohorts of ICD and CRT-D patients with similar characteristics. The primary endpoint was the time free from ES. Secondary endpoints were time free from unclustered VT/VF episodes and time free from ES in CRT-D patients according to clinical or echographic response. CRT-D was associated with a 45% relative risk reduction in ES when compared with ICD (5.6% vs. 12.3%; log rank P = 0.014). CRT-responders presented lower rates of ES when compared with non-responders and negative responders according to both clinical and echographic criteria (log-rank P = 0.017 and 0.023, respectively). No ES was detected in any of the 133 full responders to CRT-D. Clinical and echographic positive responses, but not CRT-implant per se, were associated with lower estimate rates of unclustered VTs/VFs. Conclusion: Patients with CRT had a lower incidence of ES when compared with propensity-matched ICD patients. The long-term benefit of CRT seems to be due to the improved haemodynamics, as CRT-responders performed markedly better over a long-term follow-up.

Effects of closed-loop stimulation vs. DDD pacing on haemodynamic variations and occurrence of syncope induced by head-up tilt test in older patients with refractory cardioinhibitory vasovagal syncope: the Tilt test-Induced REsponse in Closed-loop Stimulation multicentre, prospective, single blind, randomized study.

Aims: Closed-loop stimulation (CLS) seemed promising in preventing the recurrence of vasovagal syncope (VVS) in patients with a cardioinhibitory response to head-up tilt test (HUTT) compared with conventional pacing. We hypothesized that the better results of this algorithm are due to its quick reaction in high-rate pacing delivered in the early phase of vasovagal reflex, which increase the cardiac output and the blood pressure preventing loss of consciousness. Methods and results: This prospective, randomized, single-blind, multicentre study was designed as an intra-patient comparison and enrolled 30 patients (age 62.2 ± 13.5 years, males 60.0%) with cardioinhibitory VVS, carrying a dual-chamber pacemaker incorporating CLS algorithm. Two HUTTs were performed one week apart: one during DDD-CLS 60-130/min pacing and the other during DDD 60/min pacing; patients were randomly and blindly assigned to two groups: in one the first HUTT was performed in DDD-CLS (n = 15), in the other in DDD (n = 15). Occurrence of syncope and haemodynamic variations induced by HUTT was recorded during the tests. Compared with DDD, DDD-CLS significantly reduced the occurrence of syncope induced by HUTT (30.0% vs. 76.7%; P < 0.001). In the patients who had syncope in both DDD and DDD-CLS mode, DDD-CLS significantly delayed the onset of syncope during HUTT (from 20.8 ± 3.9 to 24.8 ± 0.9 min; P = 0.032). The maximum fall in systolic blood pressure recorded during HUTT was significantly lower in DDD-CLS compared with DDD (43.2 ± 30.3 vs. 65.1 ± 25.8 mmHg; P = 0.004). Conclusion: In patients with cardioinhibitory VVS, CLS reduces the occurrence of syncope induced by HUTT, compared with DDD pacing. When CLS is not able to abort the vasovagal reflex, it seems to delay the onset of syncope.

External implantable defibrillator as a bridge to reimplant after explant for infection: Experience from two centers.

BACKGROUND: The management of patients explanted for implantable converter defibrillator (ICD) infections may be complex when anti-bradycardia pacing and tachyarrhythmia protection are needed. We aimed to test the efficacy and safety of a conventional ICD externally connected to a transvenous dual-coil lead as bridging therapy before the reimplantation. METHODS AND RESULTS: We enrolled seven patients explanted for ICD infections and needed prolonged antibiotic therapy in two high-volume hospitals in Italy and treated them with a passive-can external ICD for a mean of 13 (4-30) days before reimplant. One patient experienced an electrical storm, efficaciously recognized by the external ICD and treated with antitachycardia pacing and shocks. On-demand pacing was granted for all the patients. No device-related complications were reported. CONCLUSIONS: An external ICD seems safe and efficacious as a bridge to reimplant in patients explanted for ICD infections.

Feasibility of cathodic-anodal left ventricular stimulation for alternative multisite pacing.

BACKGROUND: Simultaneous cathodic-anodal capture by a bipole of a cardiac resynchronization therapy (CRT) left-ventricular (LV) catheter may depolarize a larger LV area than conventional multipoint pacing. We evaluated the feasibility of cathodic-anodal LV stimulation. METHODS: In 30 patients undergoing CRT with a quadripolar LV lead, we evaluated the cathodic and anodal capture threshold for each LV pole and compared QRS on electrocardiogram (ECG) during single-point cathodic biventricular stimulation (S-BS), multipoint BS (M-BS), and cathodic-anodal BS (CA-BS). RESULTS: Anodal capture was obtained by three poles in 23/30 patients, by two poles in five, and was not feasible in two. The mean single-point anodal threshold was 3.93 V versus single-point cathodic threshold of 1.95 V. On comparing ECGs, M-BS and CA-BS produced similar QRS wavefront activation in 90% of patients. CONCLUSIONS: CA-BS is feasible and may be used in LV pacing to achieve a different wavefront of electrical activation. Further prospective studies are needed in order to verify the clinical impact of this kind of stimulation.

Occurrence of simultaneous cathodal-anodal capture with left ventricular quadripolar leads for cardiac resynchronization therapy: an electrocardiogram evaluation.

AIMS: The occurrence of left ventricular (LV) anodal activation during pacing with modern multipolar cardiac resynchronization therapy (CRT) systems has never been reported. The aim of our study was to demonstrate, by means of electrocardiogram (ECG) analysis, the occurrence of simultaneous cathodal-anodal LV capture with quadripolar LV leads. METHODS AND RESULTS: We studied 10 first-time recipients of a CRT device equipped with a quadripolar LV lead. During follow-up, standard supine 12-lead ECGs were obtained in available cathode-to-anode LV pacing configurations with a pulse amplitude equal to twice the pacing threshold. The occurrence of simultaneous cathodal-anodal LV capture was defined as the presence of variations in electrocardiographic ventricular activation (EVA) when the distal tip (cathode)-to-device can (anode) pacing configuration was compared with the distal tip (cathode)-to-proximal ring (anode) configuration. In eight patients, we found differences in EVA when different LV sites were paced through the unipolar LV tip and unipolar LV ring configurations. In these patients, a difference in EVA was detected in 61.5% (59 of 96) of the ECG leads (marked difference in 31.3%, slight difference in 30.2%). Changes in EVA between unipolar tip-to-can and bipolar tip-to-ring pacing that were suggestive of cathodal-anodal LV capture were found in six patients. In these patients, a total of 30 (41.7%) ECG leads showed a difference in EVA (marked difference in 20.8%, slight difference in 20.8%). CONCLUSION: In our experience, additional anodal capture by the proximal LV ring during LV pacing is provable in most recipients of a resynchronization device equipped with a multipolar LV lead.

Effect of fixed-rate vs. rate-RESPONSIve pacing on exercise capacity in patients with permanent, refractory atrial fibrillation and left ventricular dysfunction treated with atrioventricular junction aBLation and bivEntricular pacing (RESPONSIBLE): a prospective, multicentre, randomized, single-blind study.

AIMS: Atrioventricular junction (AVJ) ablation followed by biventricular pacing is an established strategy for improving symptoms and morbidity in patients with permanent atrial fibrillation (AF), reduced left ventricular ejection fraction (LVEF), and uncontrolled ventricular rate. There is no clear evidence that such patients benefit from rate-responsive (RR) pacing. METHODS AND RESULTS: This prospective, randomized, single-blind, multicentre study was designed as an intra-patient comparison and enrolled 60 patients (age 69.5 ± 11.8 years, males 63.3%, NYHA 3.0 ± 0.6) with refractory AF and reduced LVEF (mean 32.4 ± 8.3%) treated with AVJ ablation and biventricular pacing. Two 6-minute walking tests (6MWT) were performed 1 week apart: one during VVI 70/min biventricular pacing and the other during VVIR 70-130/min biventricular pacing; patients were randomly and blindly assigned to Group A (n = 29, first 6MWT in VVIR mode) or B (n = 31, first 6MWT in VVI mode). Rate-responsive activation determined an increase of 18.8 ± 24.4 m in the distance walked during the 6MWT (P < 0.001). The increase was similar in both groups (P = 0.571). A >5% increase in the distance walked was observed in 76.7% of patients. The increase in the distance walked was linearly correlated with the increase in heart rate recorded during the 6MWT in the VVIR mode (r = 0.54; P < 0.001). CONCLUSION: In permanent AF patients with uncontrolled rate and reduced LVEF who had undergone AVJ ablation and biventricular pacing, RR pacing yields a significant gain in exercise capacity, which seems to be related to the RR-induced frequency during effort.