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Background: The use of left bundle branch area pacing (LBBAP) for bradycardia pacing and cardiac resynchronization is increasing, but implants are not always successful. We prospectively studied consecutive patients to determine whether septal scar contributes to implant failure., Methods: Patients scheduled for bradycardia pacing or cardiac resynchronization therapy were prospectively enrolled. Recruited patients underwent preprocedural scar assessment by cardiac MRI with late gadolinium enhancement imaging. LBBAP was attempted using a lumenless lead (Medtronic 3830) via a transeptal approach., Results: Thirty-five patients were recruited: 29 male, mean age 68 years, 10 ischemic, and 16 non-ischemic cardiomyopathy. Pacing indication was bradycardia in 26% and cardiac resynchronization in 74%. The lead was successfully deployed to the left ventricular septum in 30/35 (86%) and unsuccessful in the remaining 5/35 (14%). Septal late gadolinium enhancement was significantly less extensive in patients where left septal lead deployment was successful, compared those where it was unsuccessful (median 8%, IQR 2%-18% vs. median 54%, IQR 53%-57%, p < .001)., Conclusions: The presence of septal scar appears to make it more challenging to deploy a lead to the left ventricular septum via the transeptal route. Additional implant tools or alternative approaches may be required in patients with extensive septal scar., (© 2023 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Introduction: A spontaneous type I electrocardiogram (ECG) pattern and/or unheralded syncope are conventionally used as risk markers for primary prevention of sudden cardiac arrest/death (SCA/SCD) in Brugada syndrome (BrS). In this study, we determine the prevalence of conventional and newer markers of risk in those with and without previous aborted SCA events., Methods: All patients with BrS were identified at our institute. History of symptoms was obtained from medical tests or from interviews. Other markers of risk were also obtained, such as presence of (1) spontaneous type I pattern, (2) fractionated QRS (fQRS), (3) early repolarization (ER) pattern, (4) late potentials on signal-averaged ECG (SAECG), and (5) response to programmed electrical stimulation., Results: In 133 patients with Bars, 10 (7%) patients (mean age = 39 ± 11 years; nine males) were identified with a previous ventricular fibrillation/ventricular tachycardia episode (n = 8) or requiring cardio-pulmonary resuscitation (n = 2). None of these patients had a prior history of syncope before their SCA event. Only two (20%) patients reported a history of palpitations or dizziness. None had apneic breathing and three (30%) patients had a family history of SCA. From their ECGs, a spontaneous pattern was only found in one (10%) of these patients. Further, 10% of patients had fQRS, 17% had late potentials on SAECG, 20% had deep S waves in lead I, and 10% had an ER pattern in the peripheral leads. No significant differences were observed in the non-SCA group., Conclusion: The majority of BrS patients with previous aborted SCA events did not have a spontaneous type I and/or prior history of syncope. Conventional and newer markers of risk appear to only have limited ability to predict SCA., (© 2018 Wiley Periodicals, Inc.)

Background: Controversy exists regarding how atrial activation mode and heart rate affect optimal atrioventricular (AV) delay in cardiac resynchronization therapy. We studied these questions using high-reproducibility hemodynamic and echocardiographic measurements., Methods: Twenty patients were hemodynamically optimized using noninvasive beat-to-beat blood pressure at rest (62 ± 11 beats/min), during exercise (80 ± 6 beats/min), and at three atrially paced rates: 5, 25, and 45 beats/min above rest, denoted as A paced,r+5 , A paced,r+25 , and A paced,r+45 , respectively. Left atrial myocardial motion and transmitral flow were timed echocardiographically., Results: During atrial sensing, raising heart rate shortened optimal AV delay by 25 ± 6 ms (P < 0.001). During atrial pacing, raising heart rate from A paced,r+5 to A paced,r+25 shortened it by 16 ± 6 ms; A paced,r+45 shortened it 17 ± 6 ms further (P < 0.001). In comparison to atrial-sensed activation, atrial pacing lengthened optimal AV delay by 76 ± 6 ms (P < 0.0001) at rest, and at ∼20 beats/min faster, by 85 ± 7 ms (P < 0.0001), 9 ± 4 ms more (P  =  0.017). Mechanically, atrial pacing delayed left atrial contraction by 63 ± 5 ms at rest and by 73 ± 5 ms (i.e., by 10 ± 5 ms more, P < 0.05) at ∼20 beats/min faster. Raising atrial rate by exercise advanced left atrial contraction by 7 ± 2 ms (P  =  0.001). Raising it by atrial pacing did not (P  =  0.2)., Conclusions: Hemodynamic optimal AV delay shortens with elevation of heart rate. It lengthens on switching from atrial-sensed to atrial-paced at the same rate, and echocardiography shows this sensed-paced difference in optima results from a sensed-paced difference in atrial electromechanical delay. The reason for the widening of the sensed-paced difference in AV optimum may be physiological stimuli (e.g., adrenergic drive) advancing left atrial contraction during exercise but not with fast atrial pacing., (© 2018 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals, Inc.)

Background: Hemodynamic optimization of cardiac resynchronization therapy (CRT) can be achieved reproducibly and--with bulky, nonimplantable equipment--noninvasively. We explored whether a simple photoplethysmogram signal might be used instead., Method: Twenty patients (age 65 ± 12) with CRT underwent automatic atrioventricular (AV) delay optimization, using a multiple-transitions protocol, at two atrially paced heart rates: just above sinus rate ("slow ApVp," 77 ± 11 beats per minute [bpm]) and 100 bpm ("fast ApVp"). We then retested to assess short-term reproducibility., Results: All 80 optimizations identified an optimum (correctly oriented parabola). At 100 bpm, the simple photoplethysmogram had wider scatter between repeat optimizations than did Finometer: standard deviation of difference (SDD) 22 ms versus 14 ms, respectively, P = 0.028. The simple photoplethysmogram improved in reproducibility when slope (instead of peak) of its signal was used for optimization, becoming as reproducible as Finometer (SDD 14 ms vs 14 ms, P = 0.50). At slow heart rate, reproducibility of simple photoplethysmogram-based optimization worsened from 14 to 22 ms (P = 0.028), and Finometer-based optimization from 14 to 26 ms (P = 0.005). Increasing the number of replicates averaged improved reproducibility. For example, SDD of simple photoplethysmogram optimization (using peak) fell from 62 ms with two replicates to 22 ms with eight replicates (P < 0.0001). At 100 bpm, the eight-replicate protocol takes ∼12 minutes., Conclusions: A 12-minute protocol of simple photoplethysmographic AV optimization can be processed fully automatically. Blinded test-retest reproducibility of the optimum AV is good and improves with more replicates. If benefits to some patients are not to be neutralized by harm to others, endpoint studies should first test check narrowness of "within-patient error bars.", (©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.)

Background: Patients receiving implantable cardioverter-defibrillators (ICDs) often have severely impaired left ventricular function and a poor prognosis. Having an ICD in situ effectively denies them the possibility of a quick, arrhythmic death. It is still unclear if and when the end of life and device deactivation should be discussed with patients and how much patients want to know prior to ICD implantation., Methods: Patients with an active ICD for chronic heart failure were interviewed regarding their attitude toward the ICD, their recollection of the consent procedure, and how they felt the end of life should be discussed with ICD patients (n = 54). Patients who had received ICD therapies (n = 25) were reviewed as a subgroup with extended questions regarding attitudes toward device deactivation., Results: Fifty-four patients were recruited. Most patients were not aware that the ICD could be deactivated. The vast majority of patients (84%) wanted to be involved in the deactivation decision; 40% felt this discussion should be prior to ICD implantation but others felt the discussion should only occur if the patient was terminally ill (16%) or in the last few days of life (5%)., Conclusion: Patients with ICDs are routinely counseled about the benefits of ICDs, but options for device deactivation are not well understood by patients. Most patients would like to be involved in deactivation decisions and we feel this should be discussed well in advance., (©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.)

Background: During optimization of the atrioventricular (AV) delay of cardiac resynchronization therapy (CRT), it is not known exactly which windows of time around the transition are most informative for identification of the optimum., Method and Results: IN 22 patients with CRT, we performed AV delay optimization using continuous noninvasive hemodynamics. We used signal-to-noise ratio to determine the most efficient averaging window location and width. We found that it is most efficient to position the averaging windows immediately before and immediately after the transition in AV delay. For example, skipping five beats after the transition decreases signal-to-noise ratio by 17.5% (P < 0.0001). Similarly, skipping five beats immediately before the transition reduces signal-to-noise ratio by 11.7% (P < 0.0001). The best choice of "fixed" averaging window width was found to be six beats, with signal-to-noise ratio falling by, for example, 41% for a one-beat window (P = 0.0002). However, even better was to set the window width for each patient to match one respiratory cycle. We observed that the pre- and posttransition signal-to-noise ratio traces begin to diverge three beats after the transition in AV delay. We believe this represents the time taken for the peripheral response to pacing-induced changes in stroke volume to occur., Conclusions: THE most efficient way to use alternating transitions for the hemodynamic optimization of CRT is to use an averaging window of one respiratory cycle, and not to skip any beats between the pretransition and posttransition averaging windows., (©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.)

Background: Atrial fibrillation (AF) is characterized by irregular atrial activation maintained by an arrhythmogenic substrate. We addressed the hypothesis that the substrate of human AF includes changes in atrial conduction properties., Methods: Patients in sinus rhythm (SR) and permanent AF undergoing cardiac surgery underwent right atrial epicardial mapping. AF was induced by burst pacing in patients in SR and was defined as sustained at >30 seconds. Epicardial maps were analyzed to determine conduction properties, AF activation patterns, and refractoriness. Patients in SR underwent postoperative Holter monitoring., Results: Thirty-seven subjects were recruited. (27 in SR and 10 in permanent AF). Sustained AF was induced in 17 patients in SR. Only patients with sustained AF developed any episodes of postoperative AF (P < 0.05), indicating the preexistence of an arrhythmogenic substrate, which was characterized by prolonged unipolar electrograms (37.0 +/- 9.4 ms vs 27.5 +/- 6.4 ms, P = 0.03), particularly in the region of the crista terminalis (41.2 ms +/- 12.1 vs 26.7 ms +/- 5.8, P = 0.004) compared with the nonsustaining group. However, these differences in electrogram characteristics were not associated with changes in wavefront propagation velocity (WPV) during SR or pacing. Activation mapping of acutely induced AF was compared with permanent AF and although there were shorter mean fibrillation intervals in permanent AF (171 +/- 16 ms vs 229 +/- 51 ms, P < 0.001), there was no difference in fibrillatory activation pattern (complexity scores: 2.21 +/- 0.52 vs 2.02 +/- 0.61) or WPV (46.9 +/- 15.4 cm/s vs 53.5 +/- 17.6 cm/s, P = 0.37). Fibrillatory activation pattern was associated with both WPV (P = 0.03) and wavelength (P = 0.03) in both pacing-induced and permanent AF., Conclusions: Patients in SR capable of sustaining pacing-induced AF have differences in electrogram duration, which are apparent before clinical episodes of AF. Although patients with permanent AF had shortening of refractoriness, there was no evidence of further changes in fibrillatory activation pattern or macroscopic wavefront propagation velocity in permanent AF. These results imply that changes occur before the onset of AF and indicate the presence of a substrate capable of maintaining AF with only alterations in refractoriness required for the development of permanent AF.

Background: It would be useful to identify patients at high risk of implantable cardioverter defibrillator (ICD) therapy via additional antiarrhythmic measures to minimize the morbidity of ICD therapies., Objective: We assessed baseline characteristics for predictors of device therapy in a general ICD population. We also compared the likelihood of therapy delivery by replacement ICDs implanted for battery depletion with the original implants., Methods: Clinical and ICD interrogation data from patients followed up at a UK center were analyzed looking for predictors of appropriate ICD therapy. Univariate and multivariate analysis was performed using Cox regression. We compared time to first appropriate therapy between first and second ICDs in patients who had undergone ICD replacement for battery depletion by log-rank testing., Results: One hundred and sixty-one patients were studied (129 men, age 65.7 +/- 12.9 years, follow-up 908 +/- 676 days). Appropriate therapy was delivered in 68 patients (42%). Univariate risk factors for appropriate ICD therapy were presentation with stable ventricular tachycardia (VT) (P = 0.0002), ischemic etiology (P = 0.03), tiered therapy programmed ICDs (P = 0.01), and beta-blocker use (P = 0.001). Stable VT and beta blocker use were independent predictors of ICD therapy on multivariate analysis. Thirty-three patients (20%) had at least one ICD replacement. Time to first appropriate therapy was no different between first and second ICD implants (P = 0.8)., Conclusion: Patients who present with cardiovascularly stable VT have a higher probability of receiving appropriate ICD therapy than those who do not. Following battery depletion of an original ICD, the replacement device is no less likely to administer therapy than the first.

Noncontact mapping identified the endocardial origins of four distinct atrial tachycardias in a young patient with drug refractory palpitations and effected successful ablation with no recurrence of symptoms in 5 months of follow-up.