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Background: Due to limited data, implantable loop recorders (ILR) are not currently recommended by the guidelines to routinely monitor patients after atrial fibrillation (AF) ablation.Aims: To validate the diagnostic value of ILR after AF ablation, modern generation ILRs (LINQ) were implanted in patients scheduled for cryoballoon ablation of AF (CBA).Methods: We included 29 patients with frequent and symptomatic episodes of paroxysmal AF. ILR was implanted 3 months prior to CBA, and data were collected before and for 6 months after the procedure. The device was programmed to maximize sensitivity of AF/ atrial tachycardia (AT) detection. All EGM recordings were "manually" assessed and annotated as true AF, pseudo AF, unrecognized AF, and episodes with no EGM available. Duration and episode-based standard performance metrics were evaluated.Results: A total number of 5,842 episodes were recorded. A total of 4,403 episodes were true AF, 453 episodes were pseudo AF, and 986 episodes had no EGM available. The device did not recognize 144 episodes of AF. Duration-based sensitivity was 95.2%, duration-based specificity 99.9%, duration-based PPV 99.2%, duration-based NPV 99.9%, episode-based sensitivity 98.0%, and episode-based PPV 91.0%. Misdiagnosis happened in 1 in 10 episodes. Total data review time was 166 hr.Conclusions: Implantable loop recorders is a valuable tool in evaluation of AF episodes in patients undergoing CBA. However, for high precision all recorded episodes need to be evaluated "manually." The memory storage space is too low for frequent AF episodes, resulting in overwriting of stored EGMs and data loss. [ABSTRACT FROM AUTHOR]

Introduction: Permanent deep septal stimulation with capture of the left bundle branch (LBB) enables maintenance/restoration of the physiological activation of the left ventricle. However, it is almost always accompanied by the simultaneous engagement of the local septal myocardium, resulting in a fused (nonselective) QRS complex, therefore, confirmation of LBB capture remains difficult. Methods: We hypothesized that programmed extrastimulus technique can differentiate nonselective LBB capture from myocardial‐only capture as the effective refractory period (ERP) of the myocardium is different from the ERP of the LBB. Consecutive patients undergoing pacemaker implantation underwent programmed stimulation delivered from the lead implanted in a deep septal position. Responses to programmed stimulation were categorized on the basis of sudden change in the QRS morphology of the extrastimuli, observed when ERP of LBB or myocardium was encroached upon, as: "myocardial," "selective LBB," or nondiagnostic (unequivocal change of QRS morphology). Results: Programmed deep septal stimulation was performed 269 times in 143 patients; in every patient with the use of a basic drive train of 600 milliseconds and in 126 patients also during intrinsic rhythm. The average septal‐myocardial refractory period was shorter than the LBB refractory period: 263.0 ± 34.4 vs 318.0 ± 37.4 milliseconds. Responses diagnostic for LBB capture ("myocardial" or "selective LBB") were observed in 114 (79.7%) of patients. Conclusions: A novel maneuver for the confirmation of LBB capture during deep septal stimulation was developed and found to enable definitive diagnosis by visualization of both components of the paced QRS complex: selective paced LBB QRS and myocardial‐only paced QRS. [ABSTRACT FROM AUTHOR]

Background: His‐bundle (HB) pacing is the most physiological method of ventricular pacing. However, it is also considered a demanding procedure with a low success rate and has suboptimal pacing parameters. There is a scarcity of data concerning HB pacing as a standard approach in patients with symptomatic bradycardia. Our goal was to compare acute and chronic results of two approaches to pacing in patients with permanent atrial fibrillation, narrow QRS complexes, and symptomatic bradycardia: right ventricular myocardial pacing versus HB pacing. Methods: Consecutive patients who received HB pacemakers were compared with historical controls—i.e., consecutive patients with classic VVI pacemaker implantations, performed by the same operator before 2014 (commencement of routine HB implantations). Acute and long‐term capture threshold, sensing, battery current drain, as well as procedure and fluoroscopy duration, complications, and success rate were compared. Results: One hundred and twenty‐five patients were analyzed (including 65 patients with HB pacing): age 73.0 ± 10.5 years, left ventricular ejection fraction of 48.2 ± 13.5%. HB pacing was inferior to right ventricular myocardial pacing in terms of higher threshold, lower sensing amplitude, higher current drain, lower success rate, longer procedure, and fluoroscopy times. However, despite this, HB procedure and fluoroscopy times of 64.4 ± 30.0 and 11.0 ± 10.7 minutes, respectively, long‐term successful HB pacing in 87.9% of patients, a chronic threshold of 1.5 ± 1.1 V, chronic sensing of 3.6 ± 2.5 mV, and chronic current drain per pulse of 3.4 ± 4.4 μAh seem acceptable. Conclusions: HB pacing can be used as an alternative standard method of pacing in atrial fibrillation patients. [ABSTRACT FROM AUTHOR]

The article presents physiological form of depolarization during right ventricular (RV) pacing, a method of resynchronization therapy for bundle branch blocks, for pacing in advanced AV block and infranodal disease. Topic include present the case of a patient with permanent HB pacing with lead implanted proximal to the site of block, who subsequently lost HB pacing because of the progression of his‐purkinje disease.

Background: Left bundle branch block (LBBB) is considered an important prognostic parameter in cardiac resynchronization therapy (CRT). We aimed to evaluate, in a sizeable cohort of patients with CRT, long-term mortality, and morbidity according to four different electrocardiographic definitions of LBBB.Methods: This longitudinal cohort study included consecutive patients who underwent CRT device implantation in our institution in years 2006-2014. Two endpoints were assessed: (a) death from any cause or urgent heart transplantation, and (b) death from any cause or heart failure admission. All preimplantation ECGs were analyzed by three physicians blinded to outcome and categorized as LBBB or non-LBBB according to four definitions.Results: A total of 552 CRT patients entered survival analysis. According to the conventional definition, 350 (63.4%) patients had LBBB, and the Marriott, WHO/AHA, and Strauss definitions identified LBBB in 254 (46.0%), 218 (39.5%) and 226 (40.9%) patients, respectively. During the 9 years of observation, 232 patients died, the combined endpoint was met by 292 patients. The Strauss LBBB definition was significantly better to the other definitions in predicting survival (Kaplan-Meier analysis with comparison of C-statistics). Multivariate Cox regression model showed that LBBB was the major determinant of all-cause mortality with the Strauss definition having the lowest hazard ratio (0.51) of the four studied definitions.Conclusions: Criteria included in various definitions of LBBB result in a diagnosis of LBBB in divergent groups of patients. Differences in LBBB definitions have clinical consequences, as patients without 'complete/true' LBBB probably get no mortality benefit from CRT. [ABSTRACT FROM AUTHOR]

Background: Despite substantial progress in the field of differentiation between ventricular tachycardia (VT) and supraventricular tachycardia (SVT) with wide QRS complexes, differentiation between VT and preexcited SVT remains largely unresolved due to significant overlap in QRS morphology. Our aim was to assess the specificities of various single ECG criteria and sets of criteria (Brugada algorithm, aVR algorithm, Steurer algorithm, and the VT score) for diagnosis of VT in a sizable cohort of patients with preexcitation.Methods: We performed a retrospective study of consecutive accessory pathway ablation procedures to identify preexcited tachycardias. Among 670 accessory pathway ablation procedures, 329 cases with good quality ECG with either bona fide preexcited SVT (n = 30) or a surrogate preexcited SVT (fast paced atrial rhythm with full preexcitation, n = 299) were identified. ECGs were analyzed with the use of wide QRS complex algorithms/criteria to determine specificities of these methods.Results: The Steurer algorithm and VT score (≥3 points), with specificities of 97.6% and 96.1%, respectively, were significantly (p < .01) more specific for the diagnosis of VT than Brugada algorithm, aVR algorithm, and Pava criterion with specificities of 31%, 11.6%, and 57.1%, respectively. The first step of the Brugada algorithm and the first step of the aVR algorithm had also high specificities of 93.3% and 96.0%, respectively.Conclusion: There are sufficient electrocardiographical differences between VT and preexcited SVT to allow electrocardiographic differentiation. VT score, Steurer algorithm, and some single criteria do not overdiagnose VT in patients with preexcitation. [ABSTRACT FROM AUTHOR]

We report three patients with intermittent loss of the preexcitation pattern in the ECG that had undergone an electrophysiological study. Despite apparently poorly conducting accessory pathway (AP), in each case a fast anterograde conduction, either during spontaneous atrial fibrillation or during incremental atrial pacing (on isoproterenol) was documented; shortest preexcited RR intervals of 200-240 ms were observed. We review the literature and conclude that intermittent preexcitation observed on resting 12-lead ECG lacks sufficient specificity for the diagnosis of an AP with long refractory period and cannot be considered a substitute for electrophysiological study in patients with this electrocardiographical phenomenon. [ABSTRACT FROM AUTHOR]

Background: Acquired long QT syndrome (a-LQTS) is associated with life-threatening ventricular arrhythmias, mainly torsades de pointes (TdP). ECG parameters predicting evolving into ventricular fibrillation (VF) are ill defined.Aims: To determine ECG parameters preceding and during TdP associated with higher risk of developing VF.Methods: We analyzed 151 episodes of TdP, recorded in 28 patients with a-LQTS (mean QTc 638 ms ± 57).Results: All 28 patients had prolonged QT interval, (mean QTc 638 ms ± 57) ranging from 502 ms to 858 ms correcting by Bazett's formula. The mean TdP heart rate was 218 bpm ± 38 (mean cycle length of TdP 274 ± 47 ms). We classified TdPs episodes into "slower"-TdP (s-TdP) < 220 bpm (range from 145-220 bpm) observed in 81 (53.6%) episodes and "faster"-TdP (f-TdP) ≥ 220 bpm (ranged from 221-281 bpm) observed in 70 (46.4%) episodes. Among 151 episodes of TdP, 21 (13.9%) were unstable (converted into VF). Out of 81 episodes of "slower"-TdP only 2 (2.5%) episodes converted into VF. The mean coupling interval (CI) of the PVC initiating TdP was 510 ms ± 118, the pause-RR interval was 1147 ms ± 335, the prematurity index (PI) of PVC that initiated TdP was 0.45 ± 0.13. The mean cycle length variability of TdP (VRV-TdP) was 30.79 ms ± 19.7. U wave was observed in 86 episodes (56.9%), among that in 69 episodes, the U/T wave ratio was > 1. Macro T wave alternans was observed in 4 patients. The QT interval was not different in patients with VF(+) and VF(-) episodes, 633 ± 60 and 639 ± 57, respectively.Conclusions: Some electrocardiographic parameters can be helpful in determining the risk of TdP evolving into VF. The slower ventricular rate (< 220 bpm), the higher rate instability (VRV > 30 ms) and the short episodes < 20 beats could predict benign evolution. [ABSTRACT FROM AUTHOR]

Hypocalcemia is mainly the consequence of hypoalbuminemia, advanced renal impairment, cirrhosis, malnutrition, or sepsis. The most common ECG manifestation of hypocalcemia is QT prolongation as a result of ST segment lengthening. Very occasionally, hypocalcemia can manifest with ST segment elevation forcing the differential diagnosis with ST elevation MI. We described a case of severe hypocalcemia manifesting in electrocardiogram with a J point elevation, absent of ST segment and with associated short QT interval mimicking acute myocardial infarction. [ABSTRACT FROM AUTHOR]

The article describes the case of a 46-year-old woman who was screened for dilated cardiomyopathy, mild heart failure and atrial fibrillation. Topics discussed include the diagnosis through electrocardiogram with the clinical tachyarrhythmia revealing the patient having a supraventricular tachyarrythmia with a retrograde concealment, similarities between supraventricular tachyarrythmia and dual nodal response techycardia (DNRT), and effects of the retrograde concealment on DNRT.

Background An accurate and universal method for diagnosis of biventricular (BiV) capture using a standard 12-lead electrocardiogram (ECG) would be useful for assessment of cardiac resynchronization therapy (CRT) patients. Our objective was to develop and validate such an ECG method for BiV capture diagnosis that would be independent of pacing lead positions-a major confounder that significantly influences the morphologies of paced QRS complexes. Methods On the basis of an evaluation of 789 ECGs of 443 patients with heart failure and various right ventricular (RV) and left ventricular (LV) lead positions, the following algorithm was constructed and validated. BiV capture was diagnosed if the QRS in lead I was predominantly negative and either V1 QRS was predominantly positive or V6 QRS was of negative onset and predominantly negative (step 1), or if QRS complex duration was <160 ms (step 2). All other ECGs were classified as loss of LV capture. Results The algorithm showed good accuracy (93%), sensitivity (97%), and specificity (90%) for detection of loss of LV capture. The performance of the algorithm did not differ among apical, midseptal, and outflow tract RV lead positions and various LV lead positions. Conclusion LV capture leaves diagnostic hallmarks in the fused BiV QRS related to different vectors of depolarization and more rapid depolarization of the ventricles. An accurate two-step ECG algorithm for BiV capture diagnosis was developed and validated. This algorithm is universally applicable to all CRT patients, regardless of the positions of the pacing leads. [ABSTRACT FROM AUTHOR]

Background: There is a paucity of data concerning the use of QRS morphology patterns for identifying pacing sites during left ventricle (LV)-only epicardial pacing in patients with a biventricular device. The objective of this study was to identify QRS patterns during LV-only pacing, and to establish their relationship with LV lead position. In addition, to validate the diagnostic performance of such electrocardiogram (ECG) patterns for predicting posterolateral versus anterior and apical versus nonapical LV pacing site. Methods: The study retrospectively analyzed data from 376 cardiac resynchronization therapy device patients. Data analyzed included ECGs registered during LV-only VVI pacing, fluoroscopic projections, and lateral chest roentgenograms that documented postimplantation LV lead position. Phase one of the study involved categorization of the ECG patterns of the first 66 study cases. Phase two of the study examined the association between ECG pattern and different LV lead positions. Results: As the LV epicardial pacing site became more anteroapical, the LV-only paced QRS complexes in the precordial leads became more negative. Three ECG patterns were identified (posterolateral, intermediate, and anteroapical), and their distribution was found to be associated with LV lead position (P < 0.001). The posterolateral ECG pattern was mostly observed in cases where the LV lead was in the posterolateral area (diagnostic accuracy of 89.1% for predicting a nonapical LV lead position). The anteroapical ECG pattern was associated with LV leads in anteroapical segments (specificity of 98.5%, accuracy of 89.1% for predicting an anteroapical pacing site). Conclusions: Posterolateral and anteroapical ECG patterns are highly predictive of LV lead position. (PACE 2012; 35:1361-1368) [ABSTRACT FROM AUTHOR]

Background: Assessment of left ventricular (LV) capture is of paramount importance in patients with biventricular (BiV) pacing. Our goal was to identify electrocardiographic features that differentiate between BiV and right ventricular (RV)-only pacing in patients with nonapical RV leads. Methods: The study enrolled 300 consecutive patients with BiV devices and nonapical RV leads, and obtained from them 558 electrocardiograms with either BiV pacing (n = 300) or RV-only pacing (n = 258). RV pacing served as a surrogate for loss of LV capture. Electrocardiograms from the first 150 patients were used to identify BiV-specific features, and to construct an algorithm to differentiate between BiV and RV-only pacing. Electrocardiograms from the second 150 patients were used to validate the algorithm. Results: The following electrocardiographic features typical of BiV pacing were identified: QS in lead V6 (specificity = 98.7%, sensitivity = 54.7%), dominant R in lead V1 (specificity = 100%, sensitivity = 23.3%), q in lead V6 (specificity = 96%, sensitivity = 22.7%), and a QRS < 160 ms (specificity = 100%, sensitivity = 66.0%). The algorithm based on those features was found to have an overall diagnostic accuracy of 95.0%, a specificity of 96.0%, and a sensitivity of 93.5%. Conclusions: The study identified QRS features that were very specific for BiV pacing in patients with nonapical RV leads. Sequential arrangement of those features resulted in an algorithm that was very accurate for differentiating between BiV pacing and loss of LV capture. (PACE 2012; 35:1199-1208) [ABSTRACT FROM AUTHOR]

The article presents a case study of 15 year of boy with Palpitations/Chest discomfort which has been later diagnosed as orthodromic atrioventricular reentrant tachycardia using a concealed right lateral accessory pathway. Topics discussed include clinical arrhythmia, ventricular tachycardia and atrial tachycardia conducting to the ventricles.

The article describes the case of a 34 year old male implanted with a dual-chamber pacemaker due to a symptomatic complete heart block apparently caused by myocarditis the patient experienced at that time. He complained of rapid heart palpitations provoked by exertion or emotions 7 years after pacemaker implantation. The findings in the patient indicate that electrocardiographic features suggestive of a long refractory period/poorly conducting accessory pathways (AP) are not reliable.

The article presents a case study of a 72‐year‐old patient with heart failure and chronic atrial fibrillation. The article discusses His bundle (HB) pacing emerges as a potential new standard ventricular pacing option, tracings that were recorded on an electrophysiology system during pacemaker implantation, and pacing threshold assessment.

The article focuses on the His bundle pacing (HBP) that allows physiological depolarization of the ventricles. It mentions that differentiation between selective (S-HBP) and nonselective His bundle pacing (NS-HBP) on the basis of subtle changes in QRS morphology using differential voltage pacing and electrocardiography (ECG) leads from the pacemaker programmer might be challenging.