Diagnostic yield of implantable loop recorders: Results from the Hellenic registry.

AIMS: Implantable loop recorders (ILRs) are increasingly being used for long-term cardiac monitoring in different clinical settings. The aim of this study was to investigate the real-world performance of ILRs-including the time to diagnosis- in unselected patients with different ILR indications. METHODS AND RESULTS: In this multicenter, observational study, 871 patients with an indication of pre-syncope/syncope (61.9%), unexplained palpitations (10.4%), and atrial fibrillation (AF) detection with a history of cryptogenic stroke (CS) (27.7%) underwent ILR implantation. The median follow-up was 28.8 ± 12.9 months. In the presyncope/syncope group, 167 (31%) received a diagnosis established by the device. Kaplan-Meier estimates indicated that 16.9% of patients had a diagnosis at 6 months, and the proportion increased to 22.5% at 1 year. Of 91 patients with palpitations, 20 (22%) received a diagnosis based on the device. The diagnosis established at 12.2% of patients at 6 months, and the proportion increased to 13.3% at 1 year. Among 241 patients with CS, 47 (19.5%) were diagnosed with AF. The diagnostic yield of the device was 10.4% at 6 months and 12.4% at 1 year. In all cases, oral anticoagulation was initiated. Overall, ILR diagnosis altered the therapeutic strategy in 26.1% in presyncope/syncope group, 2.2% in palpitations group, and 3.7% in CS group in addition to oral anticoagulation initiation. CONCLUSIONS: In this real-world patient population, ILR determines diagnosis and initiates a new therapeutic management in nearly one fourth of patients. ILR implantation is valuable in the evaluation of patients with unexplained presyncope/syncope, CS and palpitations.

Association of beat-to-beat P-wave analysis index to the extent of left atrial low-voltage areas in patients with paroxysmal atrial fibrillation.

BACKGROUND: Left atrial (LA) fibrosis has been shown to be associated with atrial fibrillation (AF) recurrence. Beat-to-beat (B2B) index is a non-invasive classifier, based on B2B P-wave morphological and wavelet analysis, shown to be associated with AF incidence and recurrence. In this study, we tested the hypothesis that the B2B index is associated with the extent of LA low-voltage areas (LVAs) on electroanatomical mapping. METHODS: Patients with paroxysmal AF scheduled for pulmonary vein isolation, without evident structural remodeling, were included. Pre-ablation electroanatomical voltage maps were used to calculate the surface of LVAs (<0.5 mV). B2B index was compared between patients with small versus large LVAs. RESULTS: 35 patients were included (87% male, median age 62). The median surface area of LVAs was 7.7 (4.4-15.8) cm2 corresponding to 5.6 (3.3-12.1) % of LA endocardial surface. B2B index was 0.57 (0.52-0.59) in patients with small LVAs (below the median) compared to 0.65 (0.56-0.77) in those with large LVAs (above the median) (p=0.009). In the receiver operator characteristic curve analysis for predicting large LVAs, the c-statistic was 0.75 (p=0.006) for B2B index and 0.81 for the multivariable model including B2B index (multivariable p=0.04) and P-wave duration. CONCLUSION: In patients with paroxysmal AF without overt atrial myopathy, B2B P-wave analysis appears to be a useful non-invasive correlate of low-voltage areas-and thus fibrosis-in the LA. This finding establishes a pathophysiological basis for B2B index and its potential usefulness in the selection process of patients who are likely to benefit most from further invasive treatment.

Cryoablation versus hybrid radiofrequency with high- and very-high-power short-duration catheter ablation for the treatment of paroxysmal atrial fibrillation.

BACKGROUND: High-power short-duration (HPSD) and very-high-power short-duration (vHPSD-90 W/4 s) radiofrequency (RF) technology has reduced the procedure time of pulmonary vein isolation (PVI) using RF without compromising the efficacy of the technique. The current study compares the novel technology of HPSD/vHPSD with cryoablation (CRYO) in terms of efficacy, safety, and procedure time in a cohort of symptomatic patients with paroxysmal atrial fibrillation (pAF). METHODS: This is a prospective, non-randomized trial. Patients with pAF received either CRYO or HPSD/vHPSD RF PVI. The primary endpoint of the study was arrhythmia recurrence in a 12 month follow-up period. Secondary endpoints included procedure time, fluoroscopy time, and safety. RESULTS: 104 patients were included (45 in HPSD/vHPSD and 59 in CRYO), with comparable characteristics between groups. The follow-up was 12.4 ± 0.5 months. There was no significant difference regarding arrhythmia recurrences during the early post-procedural period of the first 3 months (8.9% recurrences in HPSD/vHPSD versus 5.1% in CRYO-p 0.463) and in the mid-term follow-up of 12 months (17.8% recurrences in HPSD/vHPSD versus 10.2% in CRYO-p 0.385). Safety was excellent for both procedures. CRYO was a procedure of significantly shorter duration (64.64 ± 8.94 min versus 75.29 ± 18.30 min, p = 0.0001) at the expense of longer fluoroscopy time (HPSD/vHPSD 5.34 ± 1.83 versus 7.89 ± 3.70 min CRYO, p 0.001). CONCLUSIONS: HPSD/vHPSD and CRYO in pAF were comparable regarding the arrhythmia recurrence rates in a 12-month follow-up with excellent safety. The hybrid approach of HPSD/vHPSD has accelerated RF-PVI compared to conventional RF, but CRYO remains a procedure of significantly shorter duration at the expense of longer fluoroscopy time.

Cardiac contractility modulation in patients with heart failure - A review of the literature.

Experimental in vivo and in vitro studies showed that electric currents applied during the absolute refractory period can modulate cardiac contractility. In preclinical studies, cardiac contractility modulation (CCM) was found to improve calcium handling, reverse the foetal myocyte gene programming associated with heart failure (HF), and facilitate reverse remodeling. Randomized control trials and observational studies have provided evidence about the safety and efficacy of CCM in patients with HF. Clinically, CCM therapy is indicated to improve the 6-min hall walk, quality of life, and functional status of HF patients who remain symptomatic despite guideline-directed medical treatment without an indication for cardiac resynchronization therapy (CRT) and have a left ventricular ejection fraction (LVEF) ranging from 25 to 45%. Although there are promising results about the role of CCM in HF patients with preserved LVEF (HFpEF), further studies are needed to elucidate the role of CCM therapy in this population. Late gadolinium enhancement (LGE) assessment before CCM implantation has been proposed for guiding the lead placement. Furthermore, the optimal duration of CCM application needs further investigation. This review aims to present the existing evidence regarding the role of CCM therapy in HF patients and identify gaps and challenges that require further studies.

An inappropriately-appropriate ICD therapy: What is the mechanism and what interventions can be done?

Key Clinical Message: R-wave double counting is a rare cause of ventricular oversensing that can lead to inappropriate shocks. Optimizing device programming is essential for the avoidance of subsequent inappropriate therapies. Abstract: R-wave double counting is a rare cause of ventricular oversensing that can lead to inappropriate shocks. We present the case of a female patient, 52-years-old with a history of end-stage hypertrophic cardiomyopathy. The patient suffered an implantable cardioverter-defibrillator (ICD) shock. Cardiac device interrogation revealed ventricular tachycardia (VT) with a cycle length of 420 ms that was misclassified in the ventricular fibrillation (VF) zone owing to R-wave double counting. Optimizing device programming is essential for the avoidance of subsequent inappropriate therapies. Possible therapeutic options are briefly presented in the case.

Contemporary management of ventricular arrhythmias in heart failure.

Enhanced ventricular arrhythmogenesis is commonly experienced by patients in the end-stage of heart failure spectrum. A high burden of ventricular arrhythmias can affect the ventricular systolic function, lead to unexpected hospitalizations and further deteriorate the prognosis. Management of ventricular arrhythmias in this population is challenging. Implantable cardioverter-defibrillators are protective for the immediate termination of life-threatening arrhythmias but they have no impact in reducing the arrhythmic burden. Combination treatment with invasive (catheter ablation, mechanical hemodynamic support, sympathetic denervation) and noninvasive (antiarrhythmic drugs, medical therapy for heart failure, programming of implantable devices) therapies is commonly required. The aim of this review is to present the available therapeutic options, with main focus on recently published data for catheter ablation and provide a stepwise treatment approach.

Cardioneuroablation for neurally-mediated syncope: Initial experience.

Cardioneuroablation is an emerging alternative therapeutic modality for young patients with severe neurally-mediated syncope. We present two images of cardioneuroablation performed in young patients who suffered from recurrent neurally-mediated syncope with asystole and functional atrioventricular block. The patients remain syncope-free during follow-ups.

Electrocardiographic changes after balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension: Data from the Hellenic Registry.

BACKGROUND: Balloon pulmonary angioplasty (BPA) has provided an effective invasive treatment for inoperable patients with chronic thromboembolic pulmonary hypertension (CTEPH). The hemodynamic improvement achieved by BPA has significantly increased the long-term prognosis of these patients, mostly by reversing the negative remodeling of the right ventricle (RV). MATERIALS AND METHODS: In a cohort of 17 patients with symptomatic CTEPH hemodynamic data were collected before and after the completion of BPA sessions. After the confirmation of statistically significant hemodynamic improvement, we examined the changes in certain prespecified electrocardiographic (ECG) parameters (PR interval duration, QRS duration, QTc interval duration, R wave and S wave amplitude in lead I, R wave and S wave amplitude in precordial leads V1, V5 and V6) before the initiation and one month after the completion of BPA sessions. In addition, ECGs were qualitatively assessed before and after treatment for the presence of ECG abnormalities related to PH, proposed by the guidelines of the European Society of Cardiology (ESC). The term ESC criteria 1-6 was used for their description. RESULTS: Statistically significant correlation (p < 0.05) was found between the reduction in mean pulmonary artery pressure (mPAP) and the decrease of the depth of the S wave in leads I (p 0.0069), V5 (p 0.0003), V6 (p 0.0011) and in the R wave amplitude in leads V5 (p 0.0122) and V6 (p 0.0185). From the ESC criteria, RV strain pattern was the commonest in the initial cohort, with significant improvement after therapies. CONCLUSION: Hemodynamic improvement after BPA therapies is correlated with improved ECG amplitude parameters in leads I, V5 and V6. RV strain pattern is common among untreated patients with significant improvement after therapies.

Predictors of Ventricular Arrhythmias in Patients With Mitral Valve Prolapse: A Meta-analysis.

Mitral valve prolapse (MVP) has an estimated prevalence of 2-3% in the general population. Patients with MVP have an increased risk of ventricular arrhythmic events. The aim of this meta-analysis was to identify easily obtained markers that can be used for the arrhythmic risk stratification of MVP patients. This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement). The search strategy identified 23 studies that were finally included in the study. The quantitative synthesis showed that late gadolinium enhancement (LGE) [RR 6.40 (2.11-19.39), I2 77%, P = 0.001], longer QTc interval [mean difference: 14.2 (8.92-19.49) I2 0%, P < 0.001], T-wave inversion in inferior leads [RR 1.60 (1.39-1.86), I2 0%, P < 0.001], mitral annular disjunction (MAD) [RR 1.77 (1.29-2.44), I2 37%, P = 0.0005], lower left ventricular ejection fraction (LVEF) [mean difference: -0.77 (-1.48, -0.07) I2 0%, P = 0.03], bileaflet MVP [RR 1.32 (1.16-1.49), I2 0%, P < 0.001], increased anterior [mean difference: 0.45 (0.28, 0.61), I2 0%, P < 0.001] and posterior [mean difference: 0.39 (0.26, 0.52), I2 0%, P < 0.001] mitral leaflet thickness were significantly associated with ventricular arrhythmias in MVP patients. On the other hand, gender, QRS duration, anterior, and posterior mitral leaflet length were not associated with increased risk of arrhythmias. In conclusion, inferior T-wave inversions, QTc interval, LGE, LVEF, MAD, bileaflet MVP, anterior, and posterior mitral leaflet thickness are easily obtained markers that can be used for the risk stratification of patients with MVP. Prospective studies should be designed for the better stratification of this population.

Radiofrequency versus cryoballoon catheter ablation in patients with persistent atrial fibrillation: A randomized trial.

INTRODUCTION: Patients with persistent atrial fibrillation (AF) represent a challenging population for rhythm control therapies. Catheter ablation (CA) with pulmonary vein isolation (PVI) is an effective treatment option for the reduction of the arrhythmic burden. Data regarding the comparability between radiofrequency (RF) and cryoballoon ablation (CRYO) in persistent AF are limited. METHODS: This is a prospective, randomized, single-center study designed to compare the efficacy in terms of rhythm control between RF and CRYO in persistent AF. Eligible participants were randomized 2:1 in two arms: RF and CRYO. The primary endpoint of the study was arrhythmia relapse in the early postprocedural period (first 3 months) and in the middle term follow-up (3 months to 12 months). Secondary endpoints included procedure duration, fluoroscopy time, and complications. RESULTS: A total of 199 patients participated in the study (133 patients in the RF arm, 66 in the CRYO arm). No statistically significant difference occurred between the two groups regarding the primary endpoint (recurrences ≤3 months: 35.5% RF vs. 37.9% CRYO, p .755, recurrences >3 months: 26.3% RF vs. 27.3% CRYO, p .999). From the secondary endpoints, CRYO was a procedure of significantly shorter duration (75.15 ± 17.21 in CRYO vs. 136.6 ± 43.33 in RF group, p < .05). CONCLUSION: CRYO and RF ablation appear to be equally effective for rhythm control in patients with persistent AF. CRYO ablation is advantageous in terms of procedure duration.

Diagnostic and therapeutic dilemmas in a patient with myocarditis, Brugada syndrome and arrhythmic syncope.

We present a case of a previously healthy 23-year-old male who presented with chest pain, palpitations and spontaneous type 1 Brugada electrocardiographic (ECG) pattern. Positive family history for sudden cardiac death (SCD) was remarkable. Initially, clinical symptoms in combination with myocardial enzymes elevation, regional myocardial oedema with late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) and inflammatory lymphocytoid-cell infiltrates in the endomyocardial biopsy (EMB) suggested the diagnosis of a myocarditis-induced Brugada phenocopy (BrP). Under immunosuppressive therapy with methylprednisolone and azathioprine, a complete remission of both symptoms and biomarkers was accomplished. However, the Brugada pattern did not resolve. The eventually spontaneous Brugada pattern type 1 established the diagnosis of Brugada syndrome (BrS). Due to his previous history of syncope, the patient was offered an ICD that he declined. After his discharge he experienced a new episode of arrhythmic syncope. He was readmitted and received an ICD.

The value of functional substrate mapping in ventricular tachycardia ablation.

In the setting of structural heart disease, ventricular tachycardia (VT) is typically associated with a re-entrant mechanism. In patients with hemodynamically tolerated VTs, activation and entrainment mapping remain the gold standard for the identification of the critical parts of the circuit. However, this is rarely accomplished, as most VTs are not hemodynamically tolerated to permit mapping during tachycardia. Other limitations include noninducibility of arrhythmia or nonsustained VT. This has led to the development of substrate mapping techniques during sinus rhythm, eliminating the need for prolonged periods of mapping during tachycardia. Recurrence rates following VT ablation are high; therefore, new mapping techniques for substrate characterization are required. Advances in catheter technology and especially multielectrode mapping of abnormal electrograms has increased the ability to identify the mechanism of scar-related VT. Several substrate-guided approaches have been developed to overcome this, including scar homogenization and late potential mapping. Dynamic substrate changes are mainly identified within regions of myocardial scar and can be identified as local abnormal ventricular activities. Furthermore, mapping strategies incorporating ventricular extrastimulation, including from different directions and coupling intervals, have been shown to increase the accuracy of substrate mapping. The implementation of extrastimulus substrate mapping and automated annotation require less extensive ablation and would make VT ablation procedures less cumbersome and accessible to more patients.

Atrial cardiomyopathy: Diagnosis, clinical implications and unresolved issues in anticoagulation therapy.

Atrial cardiomyopathy (AC) is an evolving pathophysiological entity that has expanded our understanding regarding the atrium and its role in arrhythmogenesis and cardiac thromboembolism. The pathological myocardium in AC promotes arrhythmogenesis through mechanical dysfunction (hypocontractility, fibrosis), adverse alterations of the endothelium and secretion of prothrombotic factors (IL-6, IL-8, TNF-a). 'Red flags', indicative of AC, can be recognized either non-invasively by electrocardiography, echocardiography and cardiac magnetic resonance imaging or invasively by high-density electroanatomical mapping as low bipolar voltage areas of the affected myocardium. Signs of AC have been strongly associated with an increased risk of ischemic stroke, even embolic strokes of undetermined source, regardless of the coexistence of atrial fibrillation (AF). The underlying existence of AC has been negatively correlated with the success rate of catheter ablation of AF. The clinical value of AC is the provision of a novel pathway regarding the potential mechanisms of cerebrovascular events of cardiac thromboembolic origin. In addition, AC may serve as a risk stratification tool to predict the long-term responders of AF catheter ablation.

The role of cardiac magnetic resonance in identifying appropriate candidates for cardiac resynchronization therapy - a systematic review of the literature.

Despite the strict indications for cardiac resynchronization therapy (CRT) implantation, a significant proportion of patients will fail to adequately respond to the treatment. This systematic review aims to present the existing evidence about the role of cardiac magnetic resonance (CMR) in identifying patients who are likely to respond better to the CRT. A systematic search in the MedLine database and Cochrane Library from their inception to August 2021 was performed, without any limitations, by two independent investigators. We considered eligible observational studies or randomized clinical trials (RCTs) that enrolled patients > 18 years old with heart failure (HF) of ischaemic or non-ischaemic aetiology and provided data about the association of baseline CMR variables with clinical or echocardiographic response to CRT for at least 3 months. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement). Following our search strategy, 47 studies were finally included in our review. CMR appears to have an additive role in identifying the subgroup of patients who will respond better to CRT. Specifically, the presence and the extent of myocardial scar were associated with increased non-response rates, while those with no scar respond better. Furthermore, existing data show that scar location can be associated with CRT response rates. CMR-derived markers of mechanical desynchrony can also be used as predictors of CRT response. CMR data can be used to optimize the position of the left ventricular lead during the CRT implantation procedure. Specifically, positioning the left ventricular lead in a branch of the coronary sinus that feeds an area with transmural scar was associated with poorer response to CRT. CMR can be used as a non-invasive optimization tool to identify patients who are more likely to achieve better clinical and echocardiographic response following CRT implantation.

Atrial fibrillation and Wolff-Parkinson-White syndrome: A double blow for the cardiologist.

Electrocardiographic findings including irregularity of the rhythm, a very rapid ventricular response, and the presence of a delta wave should raise the suspicion of pre-excited atrial fibrillation with a rapid ventricular response. Urgent cardioversion is needed due to the risk of sudden cardiac death.

Predictors of fatal arrhythmic events in patients with non-compaction cardiomyopathy: a systematic review.

Left ventricular non-compaction cardiomyopathy (LVNC) is a congenital heart disease with autosomal dominant inheritance. This review aims to summarize the existing data about the predictors of fatal arrhythmias in patients with LVNC. Medline and Cochrane library databases were searched from inception to November 2021 for articles on LVNC. The reference lists of the relevant research studies as well as the relevant review studies and meta-analyses were also searched. Clinical symptoms and electrocardiogram findings such as left bundle branch block are significantly associated with ventricular arrhythmias. Other non-invasive tools such as Holter monitoring, echocardiography, and cardiac magnetic resonance (CMR) can provide additional value for risk stratification. CMR-derived left and right ventricular ejection fraction, left ventricular end-diastolic diameter, late gadolinium enhancement, and non-compacted to compacted myocardium ratio are predictive of ventricular arrhythmias. An electrophysiological study can provide additional prognostic data in patients with LVNC who are at moderate risk of ventricular arrhythmias. Risk stratification of LVNC patients with no prior history of a fatal arrhythmic event remains challenging. Symptoms assessment, electrocardiogram, Holter monitoring, and cardiac imaging should be performed on every patient, while an electrophysiological study should be performed for moderate-risk patients. Large cohort studies are needed for the construction of score models for arrhythmic risk stratification purposes.

Atrial fibrillation in hypertrophic cardiomyopathy - A contemporary mini-review.

Hypertrophic cardiomyopathy (HCM) represents the most common genetically inherited cardiovascular disorder and a leading cause of heart failure and sudden cardiac death. Atrial fibrillation (AF) is the most common arrhythmia encountered in HCM patients, primarily due to the process of left atrium dilatation and remodeling. Its presence typically leads to progressive functional decline, increased frequency of heart failure hospitalizations, and increased thromboembolic risk. In this mini-review, we summarize the contemporary data on AF pathophysiology, risk factors, and management in HCM patients suffering from AF.

P-Wave Beat-to-Beat Analysis to Predict Atrial Fibrillation Recurrence after Catheter Ablation.

The identification of patients prone to atrial fibrillation (AF) relapse after catheter ablation is essential for better patient selection and risk stratification. The current prospective cohort study aims to validate a novel P-wave index based on beat-to-beat (B2B) P-wave morphological and wavelet analysis designed to detect patients with low burden AF as a predictor of AF recurrence within a year after successful catheter ablation. From a total of 138 consecutive patients scheduled for AF ablation, 12-lead ECG and 10 min vectorcardiogram (VCG) recordings were obtained. Univariate analysis revealed that patients with higher B2B P-wave index had a two-fold risk for AF recurrence (HR: 2.35, 95% CI: 1.24-4.44, p: 0.010), along with prolonged P-wave, interatrial block, early AF recurrence, female gender, heart failure history, previous stroke, and CHA2DS2-VASc score. Multivariate analysis of assessable predictors before ablation revealed that B2B P-wave index, along with heart failure history and a history of previous stroke or transient ischemic attack, are independent predicting factors of atrial fibrillation recurrence. Further studies are needed to assess the predictive value of the B2B index with greater accuracy and evaluate a possible relationship with atrial substrate analysis.

Right ventricular outflow tract endocardial unipolar substrate mapping: implications in risk stratification of Brugada syndrome.

Brugada syndrome (BrS) is a complex arrhythmogenic disease displaying electrical and micro-structural abnormalities mainly located at the epicardium of the right ventricular outflow tract (RVOT). It is well-known that fibrosis, fatty infiltration, inflammation and reduced gap junction expression have been demonstrated at the epicardial anterior aspect of the RVOT providing the arrhythmogenic substrate for ventricular arrhythmic events in BrS. A number of models have been proposed for the risk stratification of patients with BrS. Endocardial unipolar electroanatomical mapping is an emerging tool that has been reintroduced to identify and quantify epicardial electrical abnormalities. Interestingly, current findings correlate the presence of large-sized endocardial unipolar electroanatomical abnormalities with either ventricular fibrillation inducibility during programmed ventricular stimulation or symptom status. This review aims to present existing data about the role of endocardial unipolar electroanatomical mapping for the identification of RVOT epicardial abnormalities as well as its potential clinical implications in risk stratification of BrS.