Remote Monitoring of Cardiac Implantable Electronic Devices: What is the Evidence?

PURPOSE OF REVIEW: This review offers an overview of the evidence in diagnostic and therapeutic applications of remote monitoring implantable devices. RECENT FINDINGS: Remote monitoring of cardiac implantable devices has become more and more popular in recent years as healthcare is moving towards a more patient centralized system. For heart failure patients with an ICD or pacemaker, there is controversial evidence regarding improvements in the clinical outcome, e.g., reduction of hospitalization rates or overall mortality. New developments as hemodynamic remote monitoring via measurement of the pulmonary artery pressure are promising technical achievements showing encouraging results. In cardiac remote monitoring of syncope and arrhythmias, implantable loop recorder plays an important role in diagnostic algorithms. Although there is controversial evidence according to remote monitoring of implantable devices, its use is rapidly expanding, giving healthcare providers the opportunity to react promptly to worsening of their patients. Adequate evaluation of the data created by remote monitoring systems remains an unsolved challenge of contemporary healthcare services.

Therapy of ventricular arrhythmias in patients suffering from isolated left ventricular non-compaction cardiomyopathy.

AIMS: Non-compaction cardiomyopathy (NCCM) is associated with high rates of mortality and morbidity. Knowledge regarding risk stratification, arrhythmogenesis, therapy, and prognosis is limited. The aim of this study was to analyse the outcome of patients suffering from NCCM and ventricular arrhythmias (VAs) focusing on a treatment with implantable cardioverter-defibrillator (ICD) therapy and catheter ablation. METHODS AND RESULTS: We conducted a multicentre observational study on 18 patients with NCCM, who underwent ICD implantation for secondary (n = 12) and primary (n = 6) prevention. In patients with multiple symptomatic episodes of VAs catheter ablation was performed. During a follow-up of 62 ± 42 months, 12 patients (67%) presented with appropriate ICD therapies [ventricular tachycardia (VT): n = 8; ventricular fibrillation (VF): n = 4; VT/VF: n = 3]. Ten patients underwent catheter ablation for VT/VF. Solely endocardial ablation was conducted in eight patients, and in two patients endo- and epicardial ablation was performed within the same procedure. Acute procedural success was achieved in 9/10 patients. Ventricular tachycardia recurrence was observed in two patients and the median arrhythmia free interval was 9.5 months (interquartile range 5.3-21 months). One patient underwent reablation, four patients died due to the underlying NCCM, and one patient received a left ventricular assist device. CONCLUSION: Ventricular arrhythmias are common in patients suffering from NCCM and ICD therapy may be effective for primary and secondary prevention. In our cohort, consisting of patients with multiple VA episodes and recurrent ICD therapy, catheter ablation offered a safe and effective therapeutically option.

Evaluation of thoracic impedance trends for implant-based remote monitoring in heart failure patients - Results from the (J-)HomeCARE-II Study.

AIMS: Remote monitoring by implantable devices substantially improves management of heart failure (HF) patients by providing diagnostic day-to-day data. The use of thoracic impedance (TI) as a surrogate measure of fluid accumulation is still strongly debated. The multicenter HomeCARE-II study evaluated clinically apparent HF events in the context of remote device diagnostics, focusing on the controversial role of TI. METHODS AND RESULTS: We followed 497 patients (66.6 ±â€¯10.1 years, 77% male, QRS 139.8 ±â€¯36.0 ms, ejection fraction 26.8 ±â€¯7.0%) implanted with a CRT-D (67%) or an ICD (33%) for 21.4 ±â€¯8.1 months. An independent event committee confirmed 171 HF events of which 82 were used to develop a TI-based algorithm for the prediction of imminent cardiac decompensation. Highly inter-individual variations in patterns of TI trends were observed. The algorithm resulted in a sensitivity of 41.5% (50.0%) with 0.95 (1.34) false alerts per patient year, and a positive predictive value of 7.9% overall and 27.9% in the HF event group of patients. Averaged ratio statistics showed a significant pre-hospital decrease and a highly significant in-hospital increase in TI after intensified diuresis. Recurrent decompensations turned out to be preceded by a significantly stronger decrease of TI compared to first events with a higher chance for detection (63.6% sensitivity, p < 0.05). CONCLUSIONS: Overall performance in predicting imminent decompensation by monitoring TI alone is limited due to its high inter-patient variability. TI stand-alone applications should be redirected towards a target population with more advanced symptoms where post-hospital observation aimed to maintain the patient's discharge status might be the most valuable approach. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT00711360 (HomeCARE-II) and NCT01221649 (J-HomeCARE-II).

A standardized education protocol significantly reduces traumatic injuries and syncope recurrence: an observational study in 316 patients with vasovagal syncope.

AIMS: The aim of this study was to assess the role of a non-pharmacological approach on the frequency of traumatic injuries and syncope recurrence in patients with vasovagal syncope and normal hearts. We report the experience in our syncope centre with a standardized education and teaching protocol for patients with vasovagal syncope. The treatment of vasovagal syncope is often complex and discouraging. Besides medical options, behaviour modification is a main component of therapy but has no statistical evidence to support its use. METHODS AND RESULTS: Between January 1999 and September 2006, we prospectively enrolled all patients with vasovagal syncope. The patients were counselled about the benign nature of their disease. Specific recommendations were made according to a standardized education protocol established at our syncope centre. A pre-/post-study was conducted to investigate the effectiveness of our approach on syncope recurrence and frequency of injury as the study endpoints. Complete follow-up data were available from 85% of the study population (316 of 371) after a mean time of 710 ± 286 days (mean age 50 years; standard deviation ± 18 years, 160 female). Eighty-seven patients (27.5%) had a syncope recurrence with 22 suffering an injury during syncope. During the follow-up period, the syncope burden per month was significantly reduced from 0.35 ± 0.03 at initial presentation to 0.08 ± 0.02 (P< 0.001). The frequency of traumatic syncope was significantly lower at the time of recurrence compared with the initial presentation (25 vs. 42%; McNemar's test P= 0.02). CONCLUSION: A standardized education protocol significantly reduces traumatic injuries and syncope recurrence in patients with vasovagal syncope.

Catheter ablation of stable ventricular tachycardia before defibrillator implantation in patients with coronary heart disease (VTACH): a multicentre randomised controlled trial.

BACKGROUND: In patients with ventricular tachycardia (VT) and a history of myocardial infarction, intervention with an implantable cardioverter defibrillator (ICD) can prevent sudden cardiac death and thereby reduce total mortality. However, ICD shocks are painful and do not provide complete protection against sudden cardiac death. We assessed the potential benefit of catheter ablation before implantation of a cardioverter defibrillator. METHODS: The Ventricular Tachycardia Ablation in Coronary Heart Disease (VTACH) study was a prospective, open, randomised controlled trial, undertaken in 16 centres in four European countries. Patients aged 18-80 years were eligible for enrolment if they had stable VT, previous myocardial infarction, and reduced left-ventricular ejection fraction (LVEF; 30%). Patients were followed up for at least 1 year. The primary endpoint was the time to first recurrence of VT or ventricular fibrillation (VF). Analysis was by intention to treat (ITT). This study is registered with ClinicalTrials.gov, number NCT00919373. FINDINGS: 107 patients were included in the ITT population (ablation group, n=52; control group, n=55). Two patients (one in each group) withdrew consent immediately after randomisation without any follow-up data and one patient (ablation group) was excluded because of a protocol violaton. Mean follow-up was 22.5 months (SD 9.0). Time to recurrence of VT or VF was longer in the ablation group (median 18.6 months [lower quartile 2.4, upper quartile not determinable]) than in the control group (5.9 months [IQR 0.8-26.7]). At 2 years, estimates for survival free from VT or VF were 47% in the ablation group and 29% in the control group (hazard ratio 0.61; 95% CI 0.37-0.99; p=0.045). Complications related to the ablation procedure occurred in two patients; no deaths occurred within 30 days after ablation. 15 device-related complications requiring surgical intervention occurred in 13 patients (ablation group, four; control group, nine). Nine patients died during the study (ablation group, five; control group, four). INTERPRETATION: Prophylactic VT ablation before defibrillator implantation seemed to prolong time to recurrence of VT in patients with stable VT, previous myocardial infarction, and reduced LVEF. Prophylactic catheter ablation should therefore be considered before implantation of a cardioverter defibrillator in such patients. FUNDING: St Jude Medical.

Use of an implantable loop recorder to increase the diagnostic yield in unexplained syncope: results from the PICTURE registry.

AIMS: To collect information on the use of the Reveal implantable loop recorder (ILR) in the patient care pathway and to investigate its effectiveness in the diagnosis of unexplained recurrent syncope in everyday clinical practice. METHODS AND RESULTS: Prospective, multicentre, observational study conducted in 2006-2009 in 10 European countries and Israel. Eligible patients had recurrent unexplained syncope or pre-syncope. Subjects received a Reveal Plus, DX or XT. Follow up was until the first recurrence of a syncopal event leading to a diagnosis or for ≥1 year. In the course of the study, patients were evaluated by an average of three different specialists for management of their syncope and underwent a median of 13 tests (range 9-20). Significant physical trauma had been experienced in association with a syncopal episode by 36% of patients. Average follow-up time after ILR implant was 10±6 months. Follow-up visit data were available for 570 subjects. The percentages of patients with recurrence of syncope were 19, 26, and 36% after 3, 6, and 12 months, respectively. Of 218 events within the study, ILR-guided diagnosis was obtained in 170 cases (78%), of which 128 (75%) were cardiac. CONCLUSION: A large number of diagnostic tests were undertaken in patients with unexplained syncope without providing conclusive data. In contrast, the ILR revealed or contributed to establishing the mechanism of syncope in the vast majority of patients. The findings support the recommendation in current guidelines that an ILR should be implanted early rather than late in the evaluation of unexplained syncope.

Slow wall motion rather than electrical conduction delay underlies mechanical dyssynchrony in postinfarction patients with narrow QRS complex.

INTRODUCTION: The mechanism of mechanical dyssynchrony in postinfarction patients with a narrow QRS complex is not defined but essential for cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Left ventricular electrical activation and subsequent wall motion were recorded for 16 patients with ischemic cardiomyopathy during intrinsic rhythm using a modified NOGA electromechanical mapping system. Ten patients presented mechanical dyssynchrony on tissue Doppler imaging, while 6 patients served as control subjects. The local activation time (LAT) was set by the maximum downslope of the unipolar electrogram. Local wall motion time (LMT) was defined as the time needed for the catheter tip to traverse half of its maximum inward deflection during systole. LAT and LMT were measured relative to the onset of the QRS complex. Electrical activation showed a septal-to-lateral pattern in all patients with a mean endocardial activation time of 65 +/- 13 ms. Control subjects exhibited 97.5% of all LMTs <290 +/- 17 ms. Delayed motion areas (cut-off LMT > 300 ms) showed no slowing of conduction. Wall motion time corrected for differences in electrical activation (LMT-LAT) was significantly longer in delayed (289 +/- 34 ms) than in regular (204 +/- 24 ms) motion areas (P = 0.002). Delayed motion segments were hypokinetic on echocardiography and presented a lower maximum inward motion (9.9 +/- 1.1 mm) compared to regular segments (10.9 +/- 1.2 mm) on electromechanical maps (P = 0.004). Viability, however, was preserved with unipolar and bipolar voltage amplitude >7 mV and >1.5 mV for 79% of all delayed motion areas. CONCLUSION: Dyssynchronous segments of an ischemic myocardium show unimpaired local activation but slow wall motion, thereby limiting the benefit of ventricular preexcitation via CRT.

Anatomical variations of the right coronary artery may be a source of difficult block and conduction recurrence in catheter ablation of common-type atrial flutter.

AIMS: Although Eustachian valves and recesses have been related to resistance to block, the effect of convective cooling by the right coronary artery (RCA) has not been evaluated in the clinical setting. METHODS AND RESULTS: The distance and course of the RCA in relation to the cavotricuspid isthmus (CTI) in addition to variants of CTI anatomy and the presence of Eustachian valves were analysed from computed tomography scans of 54 patients. Ablation power was titrated using a step-up protocol. Invasive follow-up was available for 34 patients. The RCA came closest to the CTI inferiorly separated by a mean of 5.3 ± 2.5 mm compared with 7.3 ± 3.3 mm septally and 5.7 ± 2.3 mm anteriorly (P < 0.01). The maximum power required for CTI block correlated inversely with the distance of the RCA to the CTI, whereas the cumulative energy was highest in the presence of recesses. Neither failure of acute block nor a higher rate of conduction recurrence could be attributed to variants of CTI anatomy or the presence of a Eustachian valve. Using multivariate analysis, a position of the RCA underneath the central part of the CTI was the only significant predictor for late conduction recurrence. These patients showed a 2.7 mm larger distance of the RCA to the tricuspid valve plane (P = 0.05). CONCLUSION: The RCA affects CTI ablation as higher power settings are required at closer distances to the ablation site. Late conduction recurrences were observed in patients with a variation of the RCA, leaving the atrioventricular groove towards the atrial aspect.

Impact of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on the long-term outcome after pulmonary vein isolation for paroxysmal atrial fibrillation.

OBJECTIVES: The effect of angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (ARBs) on the long-term outcome after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) is unknown. METHODS: This matched-pair study included 102 patients with PAF treated with ACE-I or ARBs (group 1) and 102 control subjects (group 2) after standardized PVI. Tele-ECG recorders were used to detect the end point of the first PAF recurrence after a 3-month blanking period. RESULTS: Median follow-up was 2.1 years (range 0.3-6.3). In group 1, 51 (50%) patients suffered recurrences, with a mean time to recurrence of 3.2 years (95% CI 2.6-3.8). In group 2, 67 (65.7%) patients presented PAF after a mean period of 2.2 years (95% CI 1.7-2.8; p = 0.009). A second ablation was performed in 31 (50%) patients from the treatment group and in 48 (66.7%) patients from the control group (p = 0.02). Multivariate Cox analysis showed treatment with ACE-I and ARBs to be the only significant predictor of a reduced recurrence rate (HR 0.49, 95% CI 0.32-0.75). CONCLUSION: ACE-I and ARBs were effective for the preservation of sinus rhythm after PAF ablation, and they reduced the reablation rate.

Interventricular mechanical dyssynchrony: quantification with velocity-encoded MR imaging.

PURPOSE: To evaluate the performance of velocity-encoded (VENC) magnetic resonance (MR) imaging, as compared with pulsed-wave echocardiography (PW-ECHO), in the quantification of interventricular mechanical dyssynchrony (IVMD) as a predictor of response to cardiac resynchronization therapy (CRT). MATERIALS AND METHODS: The study was approved by the local ethics committee, and all patients provided written informed consent. The study involved the examination of 45 patients (nine women, 36 men; median age, 60 years; interquartile age range, 47-69 years) with New York Heart Association class 2.0-3.0 heart failure and a reduced left ventricular ejection fraction (median, 25%; interquartile range, 21%-32%), with (n = 25) or without (n = 20) left bundle branch block. Aortic and pulmonary flow curves were constructed by using VENC MR imaging and PW-ECHO. IVMD was defined as the difference between the onset of aortic flow and the onset of pulmonary flow. Intraclass correlation coefficient, Spearman correlation coefficient, Bland-Altman, and Cohen kappa analyses were used to assess agreement between observers and methods. RESULTS: Inter- and intraobserver agreement regarding VENC MR imaging IVMD measurements was very good (intraclass r = 0.96, P < .001; mean bias, -3 msec +/- 11 [standard deviation] and 0 msec +/- 10, respectively). A strong correlation (Spearman r = 0.92, P < .001) and strong agreement (mean difference, -6 msec +/- 16) were found between VENC MR imaging and PW-ECHO in the quantification of IVMD. Agreement between VENC MR imaging and PW-ECHO in the identification of potential responders to CRT was excellent (Cohen kappa = 0.94). CONCLUSION: VENC MR measurements of IVMD are equivalent to PW-ECHO measurements and can be used to identify potential responders to CRT.

Predicting recurrence of vasovagal syncope: a simple risk score for the clinical routine.

BACKGROUND: Predictors for recurrence of syncope are lacking in patients with vasovagal syncope. The aim of this study was to identify risk factors for recurrence of syncope and develop a simple prognostic risk score of clinical value. METHODS: Two hundred seventy-six patients with a history of vasovagal syncope were prospectively followed for 2 years. Diagnosis of vasovagal syncope was based on clinical history and negative standard work-up. Inclusion in the study was independent from the result of the head-up tilt test, which was performed in all cases. Risk factors for syncope recurrence were evaluated by the Cox proportional hazards regression model and implemented in a risk score, which was validated with the log-rank test and an internal cross-validation. RESULTS: The Cox-regression analysis identified the number of previous syncopal events, history of bronchial asthma, and female gender as predictors for syncope recurrence (all P < 0.05). In contrast, head-up tilt test response had no predictive value (P = 0.881). Developing a risk score, study patients were identified as having high (recurrence rate during 2 years of follow-up: 37.2%), intermediate (24.8%), and low (6.5%) risk for syncope recurrence (receiver operating characteristic [ROC] of score 0.83, P < 0.01; Log-rank test for event-free survival, P < 0.005). CONCLUSIONS: In patients with vasovagal syncope, risk of recurrence can be stratified and is predictable based on a simple risk score.

Catheter ablation of multiple ventricular tachycardias after myocardial infarction guided by combined contact and noncontact mapping.

BACKGROUND: Insights gained from noncontact mapping of ventricular tachycardia (VT) have not been systematically applied to contact maps. This study sought to unify both techniques for an individualized approach to the patient with multiple ischemic VTs irrespective of cycle length. METHODS AND RESULTS: For 12 consecutive patients with chronic myocardial infarction and recurrent VT, bipolar contact maps were acquired during sinus or paced rhythm. Additional noncontact maps were obtained during 48 induced VTs (cycle length 192 to 579 ms). Endocardial exit sites were superimposed on contact maps and verified by pace-mapping. Radiofrequency lesions were extended for critical borders defined by multiple neighboring exits and followed the isovoltage contour line of contact maps. Nine critical borders were identified in 8 patients and constituted the substrate for 31 VTs. The voltage at exit sites was 0.8 mV (range 0.1 to 2.3). Noncontact maps revealed 23+/-18% of isthmus conduction. Thirty-seven (77%) of all and 83% of clinically documented VTs were rendered noninducible irrespective of cycle length by application of 27 radiofrequency lesions (range 18 to 56). Spontaneous transitions between distinct VTs along critical borders were demonstrated in 4 patients. Pace-mapping reproduced the QRS morphology of 81% of VTs and was associated with successful ablation (P<0.01). Noninducibility of any sustained VT was reached for 8 (67%) patients. During 15 months (range 5 to 28) of follow-up, 8 patients remained without recurrence, and VT episodes were reduced in the other 4 patients (P<0.01). VT cycle length was not predictive for acute or long-term success. CONCLUSIONS: The combined approach of contact and noncontact mapping effectively defines critical borders as the substrate of multiple VTs without limitation for unstable VTs.

Catheter ablation of paroxysmal atrial fibrillation improves cardiac function: a prospective study on the impact of atrial fibrillation ablation on left ventricular function assessed by magnetic resonance imaging.

AIMS: Beneficial effects of atrial fibrillation (AF) ablation have been demonstrated in patients with congestive heart failure (CHF) and significantly impaired left ventricular ejection fraction (LVEF). However, the impact of pulmonary vein isolation (PVI) on cardiac function in patients with paroxysmal AF and impaired LVEF remains under discussion. This study aimed to evaluate the impact of PVI for paroxysmal AF on cardiac function in patients with impaired LVEF using cardiac magnetic resonance imaging (CMRI). METHODS AND RESULTS: A total number of 70 patients with paroxysmal AF and episodes < or = 24 h were scanned on a 1.5-T-CMRI before and 6 months after PVI during sinus rhythm. End-diastolic volume, end-systolic volume, and LVEF were determined by epicardial and endocardial measurements. Patients were categorized into two groups regarding cardiac function as assessed by CMRI: group 1 patients (n = 18) with an LVEF < 50% and patients with an LVEF > 50% (group 2, n = 52). Group 1 patients demonstrated a significant lower success rate than patients of group 2 after a follow-up of 152 +/- 40 days (50 vs. 73%, P < 0.05). Cardiac magnetic resonance imaging in group 1 patients demonstrated a significant improvement in cardiac function after AF ablation (41 +/- 6 vs. 51 +/- 12%, P = 0.004), whereas group 2 patients did not show significant differences (60 +/- 6 vs. 59 +/- 9%, P = 0.22) after a 6 months follow-up. CONCLUSION: Pulmonary vein isolation improves cardiac function in patients with paroxysmal AF and impaired LVEF. These data suggest that an impaired LV function can be partially attributed to AF with short-lasting paroxysms.

Stable and unstable ventricular tachycardias in patients with previous myocardial infarction: a clinically oriented strategy for catheter ablation.

OBJECTIVE: Catheter ablation of ventricular tachycardia (VT) after myocardial infarction (MI) can be complex and time-consuming. We only targeted the previously documented VTs and those with similar or longer cycle lengths. METHODS: 30 patients with VTs after MI were included in the study. Voltage mapping was performed using an electro-anatomic mapping system (CARTOT). Stable VTs were mapped during tachycardia and unstable VTs during sinus rhythm. RESULTS: Clinical VTs were stable in 16 (53%) and unstable in 14 (47%) patients, and ablation was successful in 11 (69%) and 9 patients (64%), respectively (p = 0.42). During follow-up (14 +/- 6 months), 4 patients (25%) treated for stable and 6 (43%) for unstable VTs had recurrences (p = 0.82); ablation was successful in none and 2 (33%) of them, respectively. Non-target VTs were inducible in 11 (55%) of 20 patients after successful ablation and non-inducible in 9 (45%). During follow-up, inducibility of non-target VTs did not predict recurrences (9 vs. 11%, p = 0.88). CONCLUSIONS: Catheter ablation of VTs after MI can be successfully performed. Acute success rates seem to be similar for stable and unstable VTs. VTs faster than those documented clinically exert a minor effect on VT recurrences during follow-up.

Biphasic versus monophasic shock for external cardioversion of atrial flutter: a prospective, randomized trial.

BACKGROUND: External cardioversion is effective to terminate persistent atrial flutter. Biphasic shocks have been shown to be superior to monophasic shocks for ventricular defibrillation and atrial fibrillation cardioversion. The purpose of this trial was to compare the efficacy of rectilinear biphasic versus standard damped sine wave monophasic shocks in symptomatic patients with typical atrial flutter. METHODS: 135 consecutive patients were screened, 95 (70 males, mean age 62 +/- 13 years) were included. Patients were randomly assigned to a monophasic or biphasic cardioversion protocol. Forty-seven patients randomized to the monophasic protocol received sequential shocks of 100, 150, 200, 300 and 360 J. Forty-eight patients with the biphasic protocol received 50, 75, 100, 150 or 200 J. RESULTS: First-shock efficacy with 50-Joule, biphasic shocks (23/48 patients, 48%) was significantly greater than with the 100-Joule, monophasic waveform (13/47 patients, 28%, p = 0.04). The cumulative second-shock efficacy with the 50- and 75-Joule, biphasic waveform (39/48 patients, 81%) was significantly greater than with the 100- and 150-Joule, monophasic waveform (25/47 patients, 53%, p < 0.05). The cumulative efficacy for the higher energy levels showed naturally no significant difference between the two groups. The amount of the mean delivered energy was significantly lower in the biphasic group (76 +/- 39 J) compared to the monophasic one (177 +/- 78 J, p < 0.05). CONCLUSIONS: For transthoracic cardioversion of typical atrial flutter, biphasic shocks have greater efficacy and the mean delivered current is lower than for monophasic shocks. Therefore, biphasic cardioversion with lower starting energies should be recommended.

A new algorithm for concealed accessory pathway localization using T-wave-subtracted retrograde P-wave polarity during orthodromic atrioventricular reentrant tachycardia.

INTRODUCTION: AP localization can be predicted by analyzing the polarity of the delta wave, QRS polarity, and R/S ratio in patients with Wolff-Parkinson-White syndrome. However, the estimation of AP location is limited in patients with concealed pathways during atrioventricular reentrant tachycardias (AVRT). Thus, we analyzed retrograde P-wave polarity during orthodromic AVRT and developed an algorithm to predict the localization of concealed accessory pathways (AP). METHODS AND RESULTS: A total number of 131 patients with a single AP and inducible orthodromic AVRT were included. The initial 61 patients were analyzed retrospectively for algorithm development, whereas 70 patients were evaluated prospectively. The retrograde P-wave polarity was analyzed by subtracting the superimposing T-wave during orthodromic AVRT using custom-designed software. Four leads of the surface electrocardiogram (ECG) were identified to accurately distinguish AP locations assigned to four different regions around each AV annulus: I, aVR, aVL, and V(1). Lead V(1) was used to differentiate right (negative or isoelectric) from left (solely positive) APs. Retrograde P-wave in lead I was negative in left posterior APs exclusively and became more positive with an AP location shifting towards right anterior. P-wave polarity in lead aVR demonstrated a shift from a positive polarity from left APs to isoelectric in right APs. The opposite direction (shift from positive to isoelectric) was observed for lead aVL. The subsequently developed algorithm for concealed AP localization using these surface ECG leads demonstrated a high sensitivity, specificity, and positive predictive value particularly for common AP localizations (left posterior and inferior, and right septal) when applied in a prospective fashion. CONCLUSION: Concealed AP localization can be accurately predicted by the analysis of retrograde P-wave polarity during orthodromic AVRT using the algorithm derived from the presented study.

[Mapping and ablation of cardiac arrhythmias : Never forget where you are coming from]. / Mapping und Ablation von Herzrhythmusstörungen : "Never forget where you are coming from".

With the rapid development of new mapping and imaging technologies as well as catheter ablation technologies, it is increasingly important to understand the basic concepts of conventional mapping and ablation of cardiac arrhythmias. Prerequisite for successful ablation is the exact identification of the tachycardia mechanism and subsequent localization of the origin or tachycardic substrate. Only intracardiac electrograms provide decisive information regarding activation time and signal morphology. In some arrhythmias, it is necessary to supplement conventional mapping with so-called pace and/or entrainment mapping. This article aims to discuss and demonstrate the fundamentals of intracardiac mapping as it relates to the mapping and ablation of supraventricular and ventricular arrhythmias based on representative clinical cases. Modern three-dimensional mapping methods make it possible to individually optimize established ablation strategies with significantly better spatial resolution. The authors aimed to demonstrate that intracardiac uni- and bipolar electrograms provide essential information about timing and morphology guiding successful catheter ablation. Furthermore, our article provides useful information about conventional cardiac mapping techniques including activation mapping, pace mapping, and individual substrate mapping.

Catheter Ablation for Atrial Fibrillation in Adults With Congenital Heart Disease: Lessons Learned From More Than 10 Years Following a Sequential Ablation Approach.

OBJECTIVES: This study aimed to evaluate the impact, safety, and success of atrial fibrillation (AF) ablation in adults with congenital heart disease (ACHD) transferring ablation strategies established in normal hearts. BACKGROUND: AF is an emerging arrhythmia in ACHD. METHODS: Fifty-seven consecutive ACHD (median age 51.1 ± 14.8 years) with drug-refractory AF were analyzed who underwent catheter ablation between 2004 and 2017. CHD was classified according to its complexity into mild (61.4%), moderate (17.5%), and severe (21.1%) lesions. AF ablation was performed in 104 procedures following a sequential ablation approach. RESULTS: Of the 57 patients, 30 underwent corrective surgery, 6 underwent palliative surgery, 5 had catheter interventions, and 16 were natural survivors. Follow-up was available for all patients (median 41 ± 36 months). The median duration of cyanosis was 9.2 ± 19.7 years, and the time of volume or pressure overload prior to corrective surgery or intervention was 26.1 ± 21.2 years and 18.1 ± 15.8 years, respectively. The Kaplan-Meier estimate for arrhythmia-free survival following the index ablation procedure was 63% for 1 year and 22% for 5 years. Performing subsequent ablation procedures (2.0 ± 0.5), the Kaplan-Meier estimate significantly improved, with 99% for 1 year and 83% for 5 years (p < 0.01). Five patients died during follow-up due to their underlying CHD condition or underwent transplantation. CONCLUSIONS: AF ablation strategies established in normal hearts can be transferred to ACHD. The treatment is safe and effective with acceptable long-term results. Varying anatomical pre-conditions and the heterogeneous population itself are challenging and contribute toward a higher reablation rate. Therefore, AF ablation in ACHD should be reserved for dedicated and highly specialized teams.

Catheter motion during atrial ablation due to the beating heart and respiration: impact on accuracy and spatial referencing in three-dimensional mapping.

BACKGROUND: The accuracy of three-dimensional mapping systems is affected by cardiac contraction and respiration. OBJECTIVE: The study sought to determine relative motion of cardiac and thoracic structures to assess positional errors and guide the choice of an optimized spatial reference. METHODS: Motion of catheters placed at the coronary sinus (CS), pulmonary vein (PV) ostia, left atrial (LA) isthmus and roof, cavotricuspid isthmus (CTI), and right atrial appendage (RAA) were recorded for 30 patients using Ensite-NavX. The right subclavian vein, left brachiocephalic vein, azygos vein, pulmonary arteries, and a static reference were included. The displacement from a mean position was calculated for each pair of sites. Respiration effects were assessed by the shift of the motion curve during in- and expiration phases. RESULTS: The PVs showed a mean interpair displacement of 4.1 +/- 0.2 mm and a shift of 5.0 +/- 0.5 mm. Proximal CS references for all LA structures (4.0 +/- 1.1 mm) were superior to the static reference (4.9 +/- 0.7 mm; P = .01). In addition, the shift due to respiration was less pronounced at 3.5 +/- 0.8 mm versus 4.9 +/- 0.5 mm (P = .004), respectively. Motion of extracardiac vessels was influenced by a mean shift of 6.8 +/- 1 mm. The remote subclavian and brachiocephalic veins were more affected (7.6 +/- 0.7 mm) than the pulmonary arteries (5.9 +/- 0.4 mm; P = .002). For the CTI, a minimized mean displacement of less than 4.6 +/- 2.0 mm relative to the proximal CS, RAA, and azygos vein was found. CONCLUSION: Respiration is the major source of relative motion, which increases with distance from the heart. For LA procedures, a proximal CS reference position is superior to a static reference position.

Correlation of postural blood pressure test and head-up tilt table test in patients with vasovagal syncope.

BACKGROUND: Vasovagal syncope is triggered by complex cerebral and cardiovascular reflex mechanisms leading to general vasodilatation and bradycardia resulting in cerebral hypoperfusion. METHODS: We prospectively studied the correlation of postural blood pressure test (PBT) and head-up tilt table test (TT) in patients with recurrent vasovagal syncope. Sixty-eight patients (37 male, 52.4 +/- 18.6 years) were included in the trial. They were asked to participate in a PBT and a TT. Independent samples t-test, ANOVA and Fisher's exact test were used for statistical analysis. p values <0.05 were considered statistically significant. RESULTS: Thirty patients (44%) showed a positive TT and thirty-four patients (50%) had a positive PBT. PBT did not show any correlation with TT, although pathophysiological mechanisms in vasovagal syncope and orthostatic hypotension are supposed to be similar. Furthermore neither TT nor PBT nor their combination had any predictive value for the patient's risk of syncope recurrence. CONCLUSIONS: TT and PBT are not correlated with each other. Both investigations cannot predict the patient's risk of syncope recurrence.