Circadian variability patterns predict and guide premature ventricular contraction ablation procedural inducibility and outcomes

Three-Day Monitoring of Adhesive Single-Lead Electrocardiogram Patch for Premature Ventricular Complex: Prospective Study for Diagnosis Validation and Evaluation of Burden Fluctuation

BACKGROUND

Wearable electrocardiogram (ECG) monitoring devices are used worldwide. However, data on the diagnostic yield of an adhesive single-lead ECG patch (SEP) to detect premature ventricular complex (PVC) and the optimal duration of wearing an SEP for PVC burden assessment are limited.

OBJECTIVE

We aimed to validate the diagnostic yield of an SEP (mobiCARE MC-100, Seers Technology) for PVC detection and evaluate the PVC burden variation recorded by the SEP over a 3-day monitoring period.

METHODS

This is a prospective study of patients with documented PVC on a 12-lead ECG. Patients underwent simultaneous ECG monitoring with the 24-hour Holter monitor and SEP on the first day. On the subsequent second and third days, ECG monitoring was continued using only SEP, and a 3-day extended monitoring was completed. The diagnostic yield of SEP for PVC detection was evaluated by comparison with the results obtained on the first day of Holter monitoring. The PVC burden monitored by SEP for 3 days was used to assess the daily and 6-hour PVC burden variations. The number of patients additionally identified to reach PVC thresholds of 10%, 15%, and 20% during the 3-day extended monitoring by SEP and the clinical factors associated with the higher PVC burden variations were explored.

RESULTS

The recruited data of 134 monitored patients (mean age, 54.6 years; males, 45/134, 33.6%) were analyzed. The median daily PVC burden of these patients was 2.4% (IQR 0.2%-10.9%), as measured by the Holter monitor, and 3.3% (IQR 0.3%-11.7%), as measured in the 3-day monitoring by SEP. The daily PVC burden detected on the first day of SEP was in agreement with that of the Holter monitor: the mean difference was -0.07%, with 95% limits of agreement of -1.44% to 1.30%. A higher PVC burden on the first day was correlated with a higher daily (R2=0.34) and 6-hour burden variation (R2=0.48). Three-day monitoring by SEP identified 29% (12/42), 18% (10/56), and 7% (4/60) more patients reaching 10%, 15%, and 20% of daily PVC burden, respectively. Younger age was additionally associated with the identification of clinically significant PVC burden during the extended monitoring period (P=.02).

CONCLUSIONS

We found that the mobiCARE MC-100 SEP accurately detects PVC with comparable diagnostic yield to the 24-hour Holter monitor. Performing 3-day PVC monitoring with SEP, especially among younger patients, may offer a pragmatic alternative for identifying more individuals exceeding the clinically significant PVC burden threshold.

Non-invasive electrocardiographic mapping on the ward to guide ablation of premature ventricular contractions

Premature ventricular contracts (PVCs) are commonly encountered in clinical practice, but their ablation can prove difficult. In 15 patients with idiopathic PVCs, non-invasive mapping system View Into Ventricular Onset ™ (VIVO) in combination with 12‑lead Holter monitoring on the ward accurately guided catheter ablation via the creation of 'electrical roadmaps' of ventricular activation. This allowed for better discussions of risks and benefits with the patient prior to the procedure, and is likely to have particular advantages for patients with a low PVC burden, multiple morphologies, or difficult to reach origins.

CLINICAL PERSPECTIVE

PERSONALISED APPROACH: A novel non-invasive mapping tool in combination with technology, such as 12 lead Holter monitoring, allows for individualised, accurate prediction of PVC origin outside the electrophysiology (EP) lab.

NON-INVASIVE MAPPING

An "electrical road map" can be implemented into 3D electroanatomical mapping systems, shortening procedure times and resulting in excellent clinical outcomes.

POTENTIAL BENEFITS

VIVO could be used to improve catheter ablation outcomes for patients with infrequent PVCs, multiple morphologies and/or difficult to reach origins.

Clinical predictors and implications of cardiac inflammation detected on positron emission tomography (PET) in patients referred for premature ventricular complex (PVC) ablation

BACKGROUND

Positron emission tomography computed tomography (PET-CT) is not routinely used for premature ventricular complexes (PVCs). Whether specific clinical factors are associated with abnormal PET-CT results is not clear.

METHODS

The treatment courses and baseline characteristics of consecutive patients in a single center between 2012 and 2021, age > 18 years old, and who received ¹⁸F-fluorodeoxyglucose (FDG) PET-CT imaging for evaluation of PVCs were retrospectively analyzed.

RESULTS

A total of 102 patients was included. Of these, 27 patients (26.4%) had abnormal PET-CT and 61 (59.8%) had normal imaging. Abnormal PET-CT findings were associated with non-sustained ventricular tachycardia (NSVT) (95.2% vs. 52.6%, p = 0.001), higher number of PVC morphologies (2.29 ± 0.7 vs. 1.31 ± 0.6, p < 0.001), greater PVC coupling interval dispersion (72.47 ± 66.4 ms vs. 13.42 ± 17.9 ms, p < 0.001), and greater likelihood of fast heart rate dependent PVCs (78.5% vs. 38.2%, p = 0.017). Fourteen (51.8%) patients had an abnormal PET-CT and abnormal late gadolinium enhancement (LGE). Patients with abnormal PET-CT were more frequently treated with immunosuppression (81.4% vs. 3.2%, p < .0001) than with catheter ablation (11.1% vs. 45.9%, p = 0.002) compared to the normal PET-CT group. Over a median follow-up of 862 days (IQR 134, 1407), PVC burden decreased in both groups [from 23 ± 16% to 9 ± 10% (p < 0.001) in abnormal PET-CT group and from 21 ± 15% to 7 ± 10% (p < 0.001) in normal PET-CT group].

CONCLUSIONS

Abnormal PET-CT findings were more commonly associated with NSVT, multiform PVCs, greater PVC coupling interval dispersion, and fast heart rate dependent PVCs. LGE was not sensitive for detecting inflammation. Immunosuppression was effective in managing PVCs with abnormal PET-CT.

Hourly variability in outflow tract ectopy as a predictor of its site of origin

INTRODUCTION

Before ablation, predicting the site of origin (SOO) of outflow tract ventricular arrhythmia (OTVA), can inform patient consent and facilitate appropriate procedural planning. We set out to determine if OTVA variability can accurately predict SOO.

METHODS

Consecutive patients with a clear SOO identified at OTVA ablation had their prior 24-h ambulatory ECGs retrospectively analysed (derivation cohort). Percentage ventricular ectopic (VE) burden, hourly VE values, episodes of trigeminy/bigeminy, and the variability in these parameters were evaluated for their ability to distinguish right from left-sided SOO. Effective parameters were then prospectively tested on a validation cohort of consecutive patients undergoing their first OTVA ablation.

RESULTS

High VE variability (coefficient of variation ≥0.7) and the presence of any hour with <50 VE, were found to accurately predict RVOT SOO in a derivation cohort of 40 patients. In a validation cohort of 29 patients, the correct SOO was prospectively identified in 23/29 patients (79.3%) using CoV, and 26/29 patients (89.7%) using VE < 50. Including current ECG algorithms, VE < 50 had the highest Youden Index (78), the highest positive predictive value (95.0%) and the highest negative predictive value (77.8%).

CONCLUSION

VE variability and the presence of a single hour where VE < 50 can be used to accurately predict SOO in patients with OTVA. Accuracy of these parameters compares favorably to existing ECG algorithms.

Management of adolescent anorexia with symptomatic bradycardia and frequent premature ventricular contractions: a case report

Syncope associated with bradycardia and ventricular arrhythmia is an indication of cardiac intervention. However, in adolescent patients with anorexia nervosa, the management of syncope and arrhythmia can be different. We present a case of a 17-year-old boy who was admitted to the hospital because of syncope during exercise. Electrocardiographic monitoring showed that his mean heart rate was 41 beats/minute, with many long pauses and frequent premature ventricular contractions. These results suggested that the syncope was probably caused by arrythmia. He had been on a diet and had lost 20 kg in the past 6 months, with a body mass index of only 15.3 kg/m². He was diagnosed with anorexia nervosa. Pacemaker implantation or ablation was not performed. Refeeding therapy was performed with mirtazapine. A follow-up showed a stepwise increase in his heart rate and a stepwise decrease in premature ventricular contractions, with an increase in his body weight. The findings from this case show that vagal hyperactivity associated with anorexia nervosa might lead to multiple premature ventricular contractions and bradycardia.

Ectopic cycle length estimation from the quantified distribution patterns of ventricular bigeminy and trigeminy

Background

Ectopic cycle length (ECL) and the distribution patterns of ventricular bigeminy and trigeminy, expressed as their postextrasystolic intervals (PEIs) and interectopic intervals (IEIs), have been poorly pursued.

Objective

Based on modulation theory, we hypothesized that the PEIs of bigeminy and trigeminy determine their IEIs and ECL.

Methods

Ambulatory electrocardiograms of 1290 patients with ventricular premature complexes (≥3000/day) were studied. To quantify their distribution pattern on the PEI vs IEI curve (PIC), we introduced the following 2 ratios: PEI of trigeminy to PEI of bigeminy ratio (T/B-PEI) and IEI of trigeminy to IEI of bigeminy ratio (T/B-IEI). Distribution patterns were divided into 3 types by T/B-PEI: standard type (<0.90), intermediate type (between 0.90 and 1.20), and reverse type (>1.20). ECL was defined as the average of the bigeminy and trigeminy intervals in the standard type, and bigeminy intervals in the other 2 types.

Results

T/B-IEI disclosed significant linear relationship with T/B-PEI (P < .0001). ECLs were longest in the standard type (1905 ± 347 ms; n = 426), followed by the intermediate type (1520 ± 239 ms; n = 607) and reverse type (1317 ± 227 ms; n = 227) (P < .0001). Trigeminy PEI/ECL in the standard type (0.450 ± 0.074) was significantly shorter than that of the other 2 types (P < .0001).

Conclusion

We confirmed that T/B-PEI determines T/B-IEI and ECL by discriminating the 3 distribution patterns. Among them, trigeminy PEI/ECL decided the 2 types of modulation by the first sinus QRS, starting at the early delay phase or the later acceleration phase.

Impact of a predefined pacemapping protocol use for ablation of infrequent premature ventricular complexes: A prospective, multicenter study

BACKGROUND

Pacemapping (PM) is a useful maneuver for aiding premature ventricular complex (PVC) ablation. Its standalone clinical value is still to be defined.

OBJECTIVES

The purpose of this study was to analyze the efficacy of a predefined PM protocol for low-burden PVC ablation, regardless of their site of origin (SOO) and the presence of structural heart disease.

METHODS

This was a prospective, nonrandomized, multicenter study. The PM protocol was performed when <1 PVC/min was found. The "target area" was delimited by the 3 best matching points >94% correlation, and 3 radiofreqency (RF) applications were delivered.

RESULTS

Of 185 patients, 105 (57%) underwent activation mapping, 60 (32%) were PM-guided, and 20 (11%) were canceled due to absence of PVCs. Baseline QRS, PVC burden, and outflow tract origin were independent predictors of PM-guided ablation. A higher proportion of right ventricular outflow tract SOO in the PM group (52% vs 40%; P = .03) was observed. Mean target area was 0.6 ± 0.9 cm². Mean 10-ms isochronal area in local activation time (LAT)-guided procedures was higher (1.7 ± 2.3 cm²; P <.001). Mean number of PM matching points acquired was 39 ± 21 (range 6-98). Mean mapping and RF times were similar in both groups. However, significantly shorter procedural (53 ± 24 vs 61 ± 26 minutes; P = .04) as well as RF times (111 ± 51 vs 149 ± 149 seconds; P = .05) were needed in the PM group using the proposed protocol. Global clinical success reached 87% for the PM group and 90% (P = .58) the for LAT mapping group.

CONCLUSION

When LAT mapping is precluded, application of a PM-guided ablation protocol directed to >94% matching correlation target area is a more efficient alternative with comparable clinical results.

Pre-procedural arrhythmia burden and the outcome of catheter ablation of idiopathic premature ventricular complexes

BACKGROUND

Radiofrequency catheter ablation of idiopathic premature ventricular complexes (PVCs) is an effective method for eliminating symptoms and preventing/reversing arrhythmia-induced cardiomyopathy. One reason for procedural failure is low PVC frequency during the procedure. We aimed to investigate the relation between pre-procedural PVC burden and outcome of idiopathic PVC catheter ablation.

METHODS

Patients who underwent idiopathic PVC ablation between 2013 and 2019 at two tertiary referral centers were retrospectively included. All procedures were performed using irrigated-tip ablation catheters and a 3D electro-anatomical mapping system. Sustained ablation success was defined as a ≥80% reduction of pre-procedural PVC burden determined by 24h-Holter at follow-up.

RESULTS

Overall, 254 patients (median age 54 years [IQR 42-64]; 47% male) were enrolled. The median pre-ablation PVC-burden was 22% (IQR 11-31%), which was reduced to a post-ablation PVC burden of 0.3% (IQR 0-4%) after a median of 90 days. Sustained ablation success was achieved in 182 patients (72%). Pre-procedural PVC burden did not differ between patients with sustained ablation success and recurrence during follow-up (median 21% vs. 22%, p = .76). When assessed in pre-ablation PVC-burden groups of ≤5%, 6-15%, 16-30%, and ≥31%, sustained ablation success was achieved in 67%, 75%, 71%, and 72%, respectively, with no significant difference (p = .89). Sustained ablation outcome for PVC-burden ≤5% versus >5% showed no difference either (67% vs. 72%, p = .52).

CONCLUSIONS

Pre-procedural Holter-determined PVC burden does not predict the outcome of idiopathic PVC ablation. Thus, catheter ablation may be a reasonable first choice also for patients with symptomatic yet rare PVCs.

Predictors of adequate intraprocedural premature ventricular complex (PVC) frequency during idiopathic PVC ablation

BACKGROUND

The aim of the present study was to determine the predictors of adequate intraprocedural premature ventricular complex (PVC) frequency for successful mapping and ablation of idiopathic PVCs.

METHODS

A total of 101 consecutive patients (45 men; age: 47.9 ± 14.2 years) who had undergone idiopathic PVC ablation between 01 November 2018 and 24 June 2020 constituted our study population. Clinical and demographic data, procedural details and 24 h rhythm recordings that had been recorded before the procedure were retrospectively evaluated. Total PVC burden and diurnal variability assessed by the ratio of night time (22:00-06:00) over day time (06:00-22:00) PVC burden was calculated. The relationship between hourly PVC number and heart rate was also evaluated for each patient. Clinical characteristics and Holter parameters were compared between groups with and without adequate intraprocedural frequency of PVCs that permitted activation mapping.

RESULTS

In all, 27 patients (26.7%) had infrequent intraprocedural PVCs which necessitated isoproterenol infusion or cancellation of ablation procedure due to inability of activation mapping. PVC burden was significantly higher in the group with frequent intraprocedural PVCs (26.1 ± 9.4% vs 21.2 ± 10.3%; p: 0.026). There were no significant differences between groups regarding the relationship between hourly PVC number and heart rate or the ratio of night/day PVC burden. Binary logistic regression analysis revealed the 24 h Holter PVC burden as the sole parameter that is significant predictor of frequent intraprocedural PVCs permitting activation mapping.

CONCLUSION

The 24 h PVC burden was the only predictor of adequate intraprocedural PVC frequency permitting activation mapping during idiopathic PVC ablation.

Utility of Circadian Variability Patterns in Differentiating Origins of Premature Ventricular Complexes

Background

Premature ventricular complexes (PVCs) exhibit circadian fluctuation. We determine if PVCs of different origin exhibit specific circadian patterns.

Methods

We analyzed Holter recordings from patients with monomorphic PVCs who underwent catheter ablation. PVC circadian patterns were classified as fast-heart rate- (HR-) dependent (F-PVC), slow-HR-dependent (S-PVC), or HR-independent (I-PVC). PVC origins were determined intraprocedurally.

Results

In a retrospective cohort of 407 patients, F-PVC and S-PVC typically exhibited diurnal and nocturnal predominance, respectively. Despite decreased circadian fluctuation, I-PVC generally had heavier nocturnal than diurnal burden. PVCs of left anterior fascicle origin were predominantly S-PVC, while those of posterior hemibranch origin were mostly F-PVC. PVCs originating from the aortic sinus of Valsalva (ASV) were predominantly I-PVC, while most PVCs arising from the left ventricular outflow tract (LVOT) were F-PVC. Using a diurnal/nocturnal PVC burden ratio of 0.92 as the cutoff value to distinguish LVOT from ASV origin achieved 97% sensitivity and, as further verification, an accuracy of 89% (16/18) in a prospective cohort of patients with PVCs originating from either ASV or LVOT. In contrast, PVCs originating from right ventricles, such as right ventricular outflow tract, did not show distinct circadian patterns.

Conclusions

The circadian patterns exhibit origin specificity for PVCs arising from left ventricles. An analysis of Holter monitoring provides useful information on PVC localization in ablation procedure planning.

Predictive value of premature atrial complex characteristics in pulmonary vein isolation for patients with paroxysmal atrial fibrillation

BACKGROUND

Premature atrial complexes from pulmonary veins are the main triggers for atrial fibrillation in the early stages. Thus, pulmonary vein isolation is the cornerstone of catheter ablation for paroxysmal atrial fibrillation. However, the success rate remains perfectible.

AIM

To assess whether premature atrial complex characteristics before catheter ablation can predict pulmonary vein isolation success in paroxysmal atrial fibrillation.

METHODS

We investigated consecutive patients who underwent catheter ablation for paroxysmal atrial fibrillation from January 2013 to April 2017 in two French centres. Patients were included if they were treated with pulmonary vein isolation alone, and had 24-hour Holter electrocardiogram data before catheter ablation available and a follow-up of≥6 months. Catheter ablation success was defined as freedom from any sustained atrial arrhythmia recurrence after a 3-month blanking period following catheter ablation.

RESULTS

One hundred and three patients were included; all had an acute successful pulmonary vein isolation procedure, and 34 (33%) had atrial arrhythmia recurrences during a mean follow-up of 30±15 months (group 1). Patients in group 1 presented a longer history of atrial fibrillation (71.9±65.8 vs. 42.9±48.4 months; P=0.008) compared with those who were "free from arrhythmia" (group 2). Importantly, the daily number of premature atrial complexes before catheter ablation was significantly lower in group 1 (498±1413 vs. 1493±3366 in group 2; P=0.028). A daily premature atrial complex cut-off number of<670 predicted recurrences after pulmonary vein isolation (41.1% vs. 13.3%; sensitivity 88.2%; specificity 37.7%; area under the curve 0.635; P=0.017), and was the only independent predictive criterion in the multivariable analysis (4-fold increased risk).

CONCLUSION

Preprocedural premature atrial complex analysis on 24-hour Holter electrocardiogram in paroxysmal atrial fibrillation may improve patient selection for pulmonary vein isolation.

Long ECGs reveal rich and robust dynamical regimes in patients with frequent ectopy

We have analyzed the electrocardiographic data collected during continuous 7-day ambulatory recordings in patients with frequent premature ventricular complexes (PVCs). We analyze the dependence of the frequency and patterns of PVCs on the heart rate and the time of the day. Patients display rhythms of a complex yet consistent structure. In a given patient, the pattern remains robust over different days and particular repetitive patterns appear at specific heart rates, suggesting the appearance of bifurcations in the dynamics. Over the course of 24 h, we find that in some patients, patterns appear to depend only on the heart rate, whereas in others, both the time of the day and the heart rate play a role in controlling the dynamics. Identifying parameter values at which bifurcations occur facilitates the development of dynamical models for arrhythmia. The use of powerful recording and analysis techniques will enable improved analysis of data and better understanding of mechanisms of arrhythmia in individual patients.

Elimination of Benign Ventricular Premature Beats or Ventricular Tachycardia with Catheter Ablation versus Two Different Optimal Antiarrhythmic Drug Treatment Regimens (Sotalol or Verapamil/Flecainide)

BACKGROUND

Symptomatic idiopathic ventricular arrhythmias (VA), including premature beats (VPB) and nonsustained ventricular tachycardia (VT) are commonly encountered arrhythmias. Although these VA are usually benign, their treatment can be a challenge to primary and secondary health care providers. Mainstay treatment is comprised of antiarrhythmic drugs (AAD) and, in case of drug intolerance or failure, patients are referred for catheter ablation to tertiary health care centers. These patients require extensive medical attention and drug regimens usually have disappointing results. A direct comparison between the efficacy of the most potent AAD and primary catheter ablation in these patients is lacking. The ECTOPIA trial will evaluate the efficacy of 2 pharmacological strategies and 1 interventional approach to: suppress the VA burden, improve the quality of life (QoL), and safety.

HYPOTHESIS

We hypothesize that flecainide/verapamil combination and catheter ablation are both superior to sotalol in suppressing VA in patients with symptomatic idiopathic VA.

STUDY DESIGN

The Elimination of Ventricular Premature Beats with Catheter Ablation versus Optimal Antiarrhythmic Drug Treatment (ECTOPIA) trial is a randomized, multicenter, prospective clinical trial to compare the efficacy of catheter ablation versus optimal AAD treatment with sotalol or flecainide/verapamil. One hundred eighty patients with frequent symptomatic VA in the absence of structural heart disease or underlying cardiac ischemia who are eligible for catheter ablation with an identifiable monomorphic VA origin with a burden ≥5% on 24-h ambulatory rhythm monitoring will be included. Patients will be randomized in a 1:1:1 fashion. The primary endpoint is defined as >80% reduction of the VA burden on 24-h ambulatory Holter monitoring. After reaching the primary endpoint, patients randomized to one of the 2 AAD arms will undergo a cross-over to the other AAD treatment arm to explore differences in drug efficacy and QoL in individual patients. Due to the use of different AAD (with and without β-blocking characteristics) we will be able to explore the influence of alterations in sympathetic tone on VA burden reduction in different subgroups. Finally, this study will assess the safety of treatment with 2 different AAD and ablation of VA.

Oral caffeine intake amplifies the effect of isoproterenol in patients with frequent premature ventricular contractions

AIMS

Infrequent appearance and failed induction of premature ventricular contractions (PVCs) at catheter ablation make their localization difficult and are associated with a poor procedural outcome. This study aimed to assess the effect of preprocedural oral caffeine intake on induction of PVCs during catheter ablation.

METHODS AND RESULTS

Seventy patients (age: 54 ± 14 years, 37 men) undergoing catheter ablation for monofocal PVCs were randomized to receive oral caffeine (5 mg/kg) or placebo. Before ablation, PVC counts for 5 min were performed at baseline and during isoproterenol infusion and the isoproterenol washout period. PVC count fluctuation was defined as the difference between the highest and lowest 5-min count among the three-time periods. The 5-min PVC counts during baseline and isoproterenol infusion were equivalent between the groups. However, those during the isoproterenol washout period and PVC count fluctuation were significantly higher in the caffeine group than the control group (73.1 ± 73.2 vs. 38.9 ± 28.9 beats/5 min, P = 0.012 and 69.3 ± 61.3 vs. 37.7 ± 30.9 beats/5 min, P = 0.008, respectively). The procedure and ablation times were significantly shorter in the caffeine group than the control group (105.0 ± 23.4 vs. 136.9 ± 43.2 min, P < 0.01 and 219.1 ± 104.7 vs. 283.5 ± 136.0 sec, P < 0.01, respectively).

CONCLUSION

Oral caffeine intake amplified the effect of isoproterenol infusion on PVC induction during catheter ablation. The combined use of oral caffeine intake and isoproterenol infusion can be an option to increase intraprocedural PVCs.

Premature ventricular contractions in patients with an implantable cardioverter defibrillator cardiac resynchronization therapy device: Results from the UMBRELLA registry

Background

Premature ventricular contractions (PVC) are known to reduce the percentage of biventricular (BiV) pacing in patients with cardiac resynchronization (CRT), decreasing the clinical response. The aim of this study was to evaluate the prevalence of a high PVC burden, as well as therapeutic action (pharmacotherapy, catheter ablation or device programming), in a large CRT implantable-defibrillator (CRT-D) population.

Methods

Patients with a CRT-D device from the UMBRELLA multicenter prospective remote monitoring registry were included. The PVC count was collected from each remote monitoring transmission. Patients were divided into two high (≥1 transmission ≥200/≥400 PVC/h, respectively) and one low (all transmissions <200 PVC/h) PVC count groups. The PVC burden following a high PVC count transmission was calculated.

Results

Of 1268 patients, 135 (11%) and 43 (3.4%) presented high PVC count (≥200/≥400 PVC/h, respectively). The majority of patients in the high PVC groups were not treated (61 [79%] and 32 [74%], respectively. Considering the untreated patients in the high PVC groups, median PVC/h was 199 (interquartile range [IQR]: 196) and 271 (IQR: 330), respectively. The PVC burden (proportion of time with PVC/h ≥ 200/≥400) was 40% (IQR 70) and 29% (IQR 59), respectively.

Conclusion

A significant proportion of CRT-D patients presented a high PVC count, however, few received treatment. In the untreated patients with a high PVC count, the PVC burden during follow-up varied substantially. Several consecutive recordings of a high PVC count should be warranted before considering therapeutic action such as catheter ablation.

•

This study shows that in a large CRT-D population (UMBRELLA registry) a significant proportion presented a high PVC burden.

•

A minority received treatment aimed at reducing PVC, possibly since the high PVC count was missed during the remote transmission follow-up.

•

In untreated patients with high PVC burden temporal trends varied substantially.

•

Several consecutive recordings of a high PVC burden should be warranted before considering therapeutic action such as catheter ablation.

Mapping and Ablation of Ventricular Outflow Tract Arrhythmias

Arrhythmias arising from the ventricular outflow tracts are commonly encountered. Although largely benign, they can also present with heart failure and sudden cardiac death. Mapping and ablation of these arrhythmias is commonly performed in the electrophysiology laboratory with a high success rate, but occasionally can prove challenging to abolish. This article discusses the mapping and ablation of outflow tract arrhythmias and the challenges that can be overcome by a systematic approach.

Monomorphic Ventricular Arrhythmias in Athletes

Ventricular arrhythmias are challenging to manage in athletes with concern for an elevated risk of sudden cardiac death (SCD) during sports competition. Monomorphic ventricular arrhythmias (MMVA), while often benign in athletes with a structurally normal heart, are also associated with a unique subset of idiopathic and malignant substrates that must be clearly defined. A comprehensive evaluation for structural and/or electrical heart disease is required in order to exclude cardiac conditions that increase risk of SCD with exercise, such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Unique issues for physicians who manage this population include navigating athletes through the decision of whether they can safely continue their chosen sport. In the absence of structural heart disease, therapies such as radiofrequency catheter ablation are very effective for certain arrhythmias and may allow for return to competitive sports participation. In this comprehensive review, we summarise the recommendations for evaluating and managing athletes with MMVA.

Premature Ventricular Complex-induced Cardiomyopathy

Premature ventricular complex-induced cardiomyopathy is a potentially reversible condition in which left ventricular dysfunction is induced by the occurrence of frequent premature ventricular complexes (PVCs). Various cellular and extracellular mechanisms and risk factors for developing cardiomyopathy in this context have been suggested but the exact pathophysiological mechanism remains unclear. The suppression of PVCs is usually indicated in symptomatic patients with frequent PVCs and also those with left ventricular dysfunction. Antiarrhythmic drugs are a useful non-invasive treatment to eliminate PVCs, but the side effect profile, including the risk of pro-arrhythmia, along with suboptimal clinical effectiveness, should be weighed against the usually more effective but not risk-free treatment with catheter ablation. The latter has progressively become first line therapy in many patients with PVC-induced cardiomyopathy and should be particularly considered in specific scenarios.