Catheter Ablation of Idiopathic Epicardial Outflow Tract Premature Ventricular Contractions: A Case Report and Review of the Literature

The epicardial outflow tract can be a site of origin of idiopathic ventricular arrhythmias. These arrhythmias are most commonly perivalvular and can be targeted from within the coronary venous system or from other adjacent structures, such as the right ventricular and left ventricular outflow tracts or the coronary cusp region. The authors report a case of an epicardial idiopathic outflow tract premature ventricular contraction originating from the midseptal epicardial left ventricle. In this case, direct epicardial access was crucial to identify early local activation and achieve successful catheter ablation.

Insight from the microelectrodes in case of two different types of premature ventricular contractions originating from left ventricular summit

Premature ventricular contraction (PVC) is usually eliminated in the earliest activation site based on the conventional electrode of ablation catheter. However, the large size electrode may contain far-field potential. The QDOT MICRO ablation catheter has three micro electrodes with 0.33 mm electrode length, in addition to the conventional electrode with 3.5 mm electrode length. The micro electrodes can reflect only near-field potential. A 78-year-old with symptomatic frequent PVCs underwent catheter ablation. PVC-1 showed good pace-mapping in distal great cardiac vein (GCV). The local bipolar electrograms in the conventional electrode of ablation catheter preceded the PVC-QRS onset by 32 ms in distal GCV and 13 ms in left coronary cusp (LCC), but those in the micro electrodes preceded only by 13 ms both in distal GCV and LCC. PVC-1 was eliminated by radiofrequency (RF) application, not in distal GCV, but in LCC. PVC-2 showed good pace-mapping in LCC. The local bipolar electrograms in both the conventional electrode and the micro electrodes of ablation catheter preceded the PVC-QRS onset by 32 ms in LCC. PVC-2 was eliminated by RF application in LCC. Comparing the local electrograms of micro electrodes and the conventional electrodes may be important for identifying depth of the origin of PVCs.

Premature ventricular complexes: Assessing burden density in a large national cohort to better define optimal ECG monitoring duration

BACKGROUND

Premature ventricular contraction (PVC) burden is a risk factor for heart failure and cardiovascular death in patients with structural heart disease. Long-term electrocardiographic monitoring can have a significant impact on PVC burden evaluation by further defining PVC distribution patterns.

OBJECTIVE

This study aimed to ascertain the optimal duration of electrocardiographic monitoring to characterize PVC burden and to understand clinical characteristics associated with frequent PVCs and nonsustained ventricular tachycardia in a large US cohort.

METHODS

Commercial data (iRhythm's Zio patch) from June 2011 to April 2022 were analyzed. Inclusion criteria were age >18 years, PVC burden ≥5%, and wear period ≥13 days. PVC burden cutoffs were determined on the basis of AHA/ACC/HRS guidelines for very frequent PVCs (10,000-20,000 during 24 hours). Patients were assigned to categories by PVC densities: low, <10%; moderate, 10% to <20%; and high, ≥20%. Mean measured error was assessed at baseline and daily until the wear period's end for overall PVC burden and different PVC densities.

RESULTS

Analysis of 106,705 patch monitors revealed a study population with mean age of 70.6 ± 14.6 years (33.6% female). PVC burden was higher in male patients and those >65 years of age. PVC burden mean error decreased from 2.9% at 24 hours to 1.3% at 7 days and 0.7% at 10 days. Number of ventricular tachycardia episodes per patient increased with increasing PVC burden (P < .0001).

CONCLUSION

Extending ambulatory monitoring beyond 24 hours to 7 days or more improves accuracy of assessing PVC burden. Ventricular tachycardia frequency and duration vary by initial PVC density, highlighting the need for prolonged cardiac monitoring.

A "two-step classification" machine learning method for non-invasive localization of premature ventricular contraction origins based on 12-lead ECG

BACKGROUND

Premature ventricular contraction (PVC) is a type of cardiac arrhythmia that originates from ectopic pacemaker in the ventricles. The localization of the origin of PVC is essential for successful catheter ablation. However, most studies on non-invasive PVC localization focus on elaborate localization in specific regions of the ventricle. This study aims to propose a machine learning algorithm based on 12-lead electrocardiogram (ECG) data that can improve the accuracy of PVC localization in the whole ventricle.

METHODS

We collected 12-lead ECG data from 249 patients with spontaneous or pacing-induced PVCs. The ventricle was divided into 11 segments. In this paper, we propose a machine learning method consisting of two consecutive classification steps. In the first classification step, each PVC beat was labeled to one of the 11 ventricular segments using six features, including a newly proposed morphological feature called "Peak_index." Four machine learning methods were tested for comparative multi-classification performance and the best classifier result was kept to the next step. In the second classification step, a binary classifier was trained using a smaller combination of features to further differentiate segments that are easily confused.

RESULTS

The Peak_index as a proposed new classification feature combined with other features is suitable for whole ventricle classification by machine learning methods. The test accuracy of the first classification reached 75.87%. It is shown that a second classification for confusable categories can improve the classification results. After the second classification, the test accuracy reached 76.84%, and when a sample classified into adjacent segments was considered correct, the test "rank accuracy" was improved to 93.49%. The binary classification corrected 10% of the confused samples.

CONCLUSION

This paper proposes a "two-step classification" method to localize the origin of PVC beats into the 11 regions of the ventricle using non-invasive 12-lead ECG. It is expected to be a promising technique to be used in clinical settings to help guide ablation procedures.

Assessment of subtle cardiac dysfunction induced by premature ventricular contraction using two-dimensional strain echocardiography and the effects of successful ablation

INTRODUCTION AND OBJECTIVES

We aimed to assess the effects of successful ablation on impaired left ventricular global longitudinal strain (LV-GLS) in patients with frequent premature ventricular contractions (PVCs). We also evaluated the potential risk factors of impaired LV-GLS.

METHODS

Thirty-six consecutive patients without any structural heart disease, who were treated with radiofrequency (RF) ablation due to frequent PVCs, were included in the study. All patients were evaluated with standard transthoracic and two-dimensional speckle tracking echocardiography.

RESULTS

Mean LV-GLS before ablation was 17.3±3.7 and 20.5±2.6 after ablation; the difference was statistically significant (p<0.01). Patients were categorized into two groups: those with LV-GLS value >-16% and those ≤16%. Low PVC E flow/post-PVC E flow and PVC SV/post-PVC SV ratios were associated with impaired LV-GLS.

CONCLUSION

In symptomatic patients with frequent PVCs and normal left ventricular ejection fraction, we observed significant improvement in LV-GLS value following successful RF ablation. Patients with impaired LV-GLS more often display non-ejecting PVCs and post-extrasystolic potentiation (PEP) compared to patients with normal LV-GLS.

Association between excess catecholamine synthesis and polymorphic premature ventricular contraction

BACKGROUND

The reasons for the etiology of premature ventricular contractions (PVCs) are not specifically known. Many patients are resistant to medical treatment, and a factor that would predict response to medical treatment cannot be identified. This study aims to investigate if a high catecholamine level results in polymorphic PVC.

METHODS

This study was obtained by prospective data registry analysis. A total of 100 patients, 50 from the PVC group, and 50 from the control group have been evaluated. The participants who were included in the patient group had a polymorphic PVC of 5% or more in their 24-h Holter evaluations. Metanephrine showing the level of adrenaline and normetanephrine, showing the level of noradrenaline levels have been measured from these urine samples.

RESULT

There was no difference between the two groups in terms of biochemical and essential characteristics. Normetanephrine level has been significantly higher in the PVC group compared to the control group (323.9 ± 208.9 μg to 129.25 ± 67.88 μg; p < 0.001). Similarly, metanephrine level has also been higher in the PVC group (124.75 ± 82.43 μg to 52.615 ± 36,54 μg; p < 0.001). A positive and moderate correlation has been identified between the number and ratio of PVC and the metanephrine and normetanephrine levels.

CONCLUSION

In this study, we found that the catecholamine levels were higher in the polymorphic PVC group than in the healthy volunteers. Also, an increase in the number and rate of PVC has been observed as the catecholamine levels increased.

CLINICAL TRIAL REGISTRATION

Urine Levels of Metanephrine and Normetanephrine in Patients With Frequent PVC; ClinicalTrials.gov number NCT03447002.

Combining contact force and local impedance to treat idiopathic premature ventricular contractions from the outflow tracts: impact of ablation strategy on outcomes

BACKGROUND

Contact force (CF)-sensing catheters have not proved superior to standard catheters in the ablation of premature ventricular contractions (PVCs) from the right and left ventricular outflow tract (RVOT, LVOT). In this context, the utility of measuring local impedance (LI) is not known. We aimed to ascertain whether the use of a catheter combining LI and CF information was associated with superior outcomes in comparison with other catheter technologies.

METHODS

We compared three groups of 40 propensity-matched patients with PVCs from the OTs, ablated by means of different catheter technologies: a CF-plus LI-featured catheter, an LI-featured catheter, and a standard irrigated catheter.

RESULTS

The CF + LI group displayed a significantly lower risk of PVC recurrence than the standard ablation group (HR, 0.22; 95%CI, 0.07-0.71; p = 0.01). In the CF + LI group, LI drop and RF time were the only predictors of successful lesions (OR = 1.19, CI: 1.13-1.26, p < 0.001; OR = 1.06 CI: 1.01-1.07, p = 0.044, respectively). In the coronary cusps, unlike the RVOT/LVOT region, CF was not associated with LI drop (p = 0.48), and RF duration showed a linear relationship with LI drop (p < 0.001).

CONCLUSIONS

The use of ablation catheters that combine CF and LI information is associated with increased success in the RF ablation of PVCs from the OTs. LI drop is the most important predictor of effective lesions, but its behavior depends on the ablation site: in the coronary cusps, unlike the RVOT/LVOT region, longer RF application times are needed in order to achieve LI drops associated with successful outcomes. REGISTRY AND REGISTRATION NO.

OF THE STUDY/TRIAL

NCT03793998.

Successful treatment of frequent premature ventricular contractions and non-sustained ventricular tachycardia with verapamil and flecainide in RYR1-related myopathy: a case report

Background

Ryanodine receptor 1 (RYR1)-related myopathies are a group of congenital muscle diseases caused by RYR1 mutations. These mutations may cause centronuclear myopathy, a congenital neuromuscular disorder characterized by clinical muscle weakness and pathological presence of centrally placed nuclei on muscle biopsy. Mutations in RYR2 cause ventricular arrhythmias that can be treated with flecainide; however, reports of ventricular arrhythmias in RYR1-related myopathies are rare. Herein we report a case of centronuclear myopathy with RYR1 mutations who exhibited frequent premature ventricular contractions (PVCs) and non-sustained ventricular tachycardia (NSVT), which was successfully treated with verapamil and flecainide.

Case summary

At 7 months, the patient presented neurological manifestations of hypotonia and delayed motor development. A skeletal muscle biopsy performed at age 4 years led to the diagnosis of centronuclear myopathy. At age 15 years, frequent PVCs and NSVT were identified on the electrocardiogram and 24 h Holter monitoring. Treatment with verapamil was initiated; however, it was not beneficial. Therefore, flecainide was added to the treatment, decreasing the frequency of PVCs and NSVT. Non-sustained ventricular tachycardia disappeared at the age of 21, and PVCs almost disappeared at the age of 22. Genetic testing revealed c.13216delG (p.E4406Rfs*35), c.14874G>C (p.K4958N), and c.9892G>A (p.A3298T) in RYR1, and the compound heterozygosity of variants was confirmed by analysis of the parents.

Discussion

This is the first report of ventricular arrhythmia associated with RYR1-related myopathy that was successfully treated with verapamil and flecainide. The combination of verapamil and flecainide may be a useful treatment option for ventricular arrhythmias in patients with RYR1-related myopathies.

Initial negative concordance on unipolar and bipolar electrograms: a novel parameter for localizing the origin of premature ventricular contractions arising from pulmonary sinus cusps

BACKGROUND

The features of the unipolar electrogram (UEGM) and bipolar electrogram (BEGM) have been utilized to identify the site of origin of idiopathic premature ventricular contractions (PVCs) arising from pulmonary sinus cusps (PSCs), but for these PVCs, whether a negative concordance in the initial waves of both EGMs recorded above pulmonary valves can be used as a parameter to localize the origin has not been previously studied. We aimed to assess whether an initial negative concordance (INC) between the UEGM and BEGM might determine the origin of PVCs mapped and ablated within PSCs.

METHODS

Data were collected from 22 patients undergoing successful radiofrequency catheter ablation for symptomatic idiopathic PVCs within PSCs. The morphological features of both the UEGM and the BEGM recorded at all ablation sites were analyzed.

RESULTS

A total of 109 sites within PSCs were ablated in 22 patients with an age (mean ± SD) of 47.2 ± 17.2 years. Ablation resulted in procedural success in all patients. The INC was observed at 18 of 22 (81.8%) successful ablation sites, contrasted with 3 of 87 (3.4%) unsuccessful sites (P < 0.001). The INC was consistent with the outcomes of conventional mapping parameters and proved to be an additional useful predictor of ablation success, with a sensitivity, specificity, positive predictive value and negative predictive value of 81.8%, 96.6%, 85.7% and 95.5%, respectively.

CONCLUSIONS

An INC between the UEGM and the BEGM can predict the origin of PVCs arising from PSCs. An initial negative concordance between unipolar and bipolar electrograms indicates that the distal electrode of the ablation catheter is at the origin of premature ventricular contractions within pulmonary sinus cusps.

Short-Coupled Ventricular Fibrillation

Short-coupled ventricular fibrillation (SCVF) is a distinct phenotype among individuals with unexplained cardiac arrest accounting for 7% to 14% of cases of idiopathic ventricular fibrillation (IVF). VF is typically initiated by a trigger premature ventricular contraction with a short-coupling interval of less than 350 milliseconds. In the absence of specific electrocardiographic features or provocative tests, the diagnosis remains challenging and requires documentation of VF onset. Most cases are diagnosed during follow-up at the time of VF recurrence. SCVF is characterized by a high risk of VF recurrence. Insertion of an implantable cardioverter-defibrillator and quinidine are the keystones of SCVF management.

Multielectrode mapping for premature ventricular contraction ablation - A prospective, multicenter study

PURPOSE

We aim to evaluate whether the use of a multielectrode mapping catheter could lead to higher efficacy of premature ventricular contraction (PVC) ablation.

METHODS

Prospective, multicenter nonrandomized study of consecutive patients referred for PVC ablation from January 2018 to June 2021. Patients were separated into two groups: activation map performed with the PentaRay catheter (Study group) or with the ablation catheter (Control group). PMF software was used in both groups. Procedural endpoints and 1-year freedom from ventricular arrhythmia were assessed.

RESULTS

During the enrollment period 136 patients (60% males, mean age of 55 ± 17 years, 60% left-sided origin) fulfilled the inclusion criteria - 68 patients in each group. Patients in the Study Group had a sevenfold higher number of acquired activation points (768 ± 728 vs. 110 ± 79, p < 0.01), a shorter mapping time (28 ± 19 min vs. 49 ± 32 min, p < 0.01) and a quicker procedure time (110 ± 33 min vs. 134 ± 50 min, p < 0.01), compared to patients in the Control Group. While there were no significant differences in the acute success (95.6% in the Study Group vs. 90.1% in Control group, p = 0.49), or adverse events (4% in the Study group vs. 7% in the Control group, p = 0.72), patients in the Study group had a higher freedom from ventricular arrhythmia at 1-year (89.7% vs. 70.6%, p = 0.01). The use of the PentaRay catheter was an independent predictor of success (HR = 6.20 [95% CI, 1.08-35.47], p = 0.003).

CONCLUSIONS

The use of the PentaRay catheter may improve the outcome of PVC ablation while reducing procedure time.

Anesthetic management of a patient with preoperative R-on-T phenomenon undergoing laparoscopic-assisted sigmoid colon resection: A case report

BACKGROUND

The R-on-T phenomenon is a malignant arrhythmia associated with potentially catastrophic consequences. It may initiate ventricular tachycardia or ventricular fibrillation, which can result in syncope or sudden cardiac death. This manifestation poses a great challenge for anesthesiologists. However, it is rarely encountered in the perioperative setting.

CASE SUMMARY

We herein present a case in which the R-on-T phenomenon was incidentally revealed by 24-h Holter monitoring in a patient diagnosed with sigmoid colon cancer. Careful evaluation and treatment with mexiletine were carried out preoperatively under consultation with a cardiovascular specialist, and surgery was uneventfully performed under general anesthesia after thorough preparation.

CONCLUSION

Physicians should be vigilant about this infrequent but potentially fatal arrhythmia. Our experience suggests that the anesthetic process can be greatly optimized with careful preparation.

RVOT premature ventricular contractions induce significant anatomical displacement during 3D mapping: A cause of mid-term ablation failure?

BACKGROUND

Catheter ablation is a first-line treatment for symptomatic right ventricular outflow tract (RVOT) premature ventricular complexes (PVCs). There is evidence of displacement of the ablation target site during PVCs relative to the location in sinus rhythm (SR).

AIM

To analyse the extent of displacement induced by RVOT PVCs and its effect on the ablation sites and the mid-term efficacy of ablation.

METHODS

In this multicentre French study, we retrospectively included 18 consecutive adults referred for ablation of RVOT PVCs using a three-dimensional (3D) mapping system. PVC activation maps were performed conventionally (initial map), then each PVC activation point was manually reannotated considering the 3D location on a previous SR beat (corrected map). The ablation-site locations on the initial or the corrected area, including the 10 best activation points, were analysed. Mid-term efficacy was evaluated.

RESULTS

The direction of map shift during PVCs relative to the map in SR occurred along a vertical axis in 16 of 18 patients. The mean activation-point displacement for each of the 18 mapped chambers was 5.6±2.2mm. Mid-term recurrence of RVOT PVCs occurred in 5 (28%) patients. In all patients with recurrences, no significant ablation lesion was located on the corrected (true) site of origin.

CONCLUSIONS

RVOT PVCs induce a vertical anatomical shift that can mislead physicians about the true location of the arrhythmia's site of origin. Our study highlights the association between mid-term PVC recurrence and the absence of spatial overlap between ablation points and the corrected site of origin.

The Effect of Bisoprolol on Premature Ventricular Complex in Vietnamese Patients with Hypertension and Left Ventricular Hypertrophy

BACKGROUND

Premature ventricular contraction (PVC) is a common arrhythmia that causes a large number of clinical symptoms, adversely impacts the quality of life, and can even initiate serious arrhythmias, such as ventricular tachycardia or ventricular fibrillation. The incidence of premature ventricular contraction is higher in hypertensive patients, particularly if concomitant left ventricular hypertrophy (LVH) is present.

OBJECTIVES

This study was conducted on the characteristics of PVC in hypertensive patients with left ventricular hypertrophy and aimed to evaluate the effect of bisoprolol on PVC in Vietnamese patients with hypertension and LVH.

SUBJECTS AND METHODS

We conducted a study to determine how bisoprolol potency affected PVC management in the group with both high blood pressure and LVH. We selected a convenient sample of all patients who came to the Medical Examination Department at the Can Tho University of Medicine and Pharmacy Hospital and met sampling criteria with hypertension, LVH on echocardiography, and PVC on 12-leads electrocardiogram. Over 2 years, we collected 76 patients who satisfied the above conditions. Out of which, 50 patients were indicated for management with bisoprolol, and 26 patients were excluded from the study, including 7 patients with asthma and 19 patients who had simple PVC on a 24-hour Holter ECG. Data were analyzed with SPSS version 22.

RESULTS

Fifty patients participated in the study, of whom 70% were female. It is clear that palpitation was the most prevalent symptom (66%), and 38% of patients had complicated PVC (Lown III-V). When treating PVC with bisoprolol, 50% of patients achieved the treatment goal with a decrease in the number of PVCs of more than 70%, accompanied by symptom relief and eradication of dangerous PVCs. After 4 weeks of treatment, bisoprolol decreased the number of PVCs, heart rate, and blood pressure while also easing PVC-related symptoms (p < 0.05).

CONCLUSION

Low-dose bisoprolol effectively reduces the number of PVCs in hypertensive patients with LVH.

Cardiopulmonary capacity is reduced in children with ventricular arrhythmia

BACKGROUND

Premature ventricular contractions (PVCs) are frequently seen in children and are considered benign. A substantial group of adolescents with PVCs complain about a broad range of clinical symptoms, including low exertion tolerance.

OBJECTIVE

The purpose of this study was to evaluate prospectively whether ventricular arrhythmia affects physical performance in adolescents with normal left ventricular function, using a cardiopulmonary exercise test (CPET) and evaluating the electrocardiographic (ECG) characteristics of patients with PVCs with regard to exercise capacity.

METHODS

The study group consisted of 49 children with PVCs and normal left ventricular function. The control group consisted of 36 healthy volunteers. Standard ECG, 24-hour Holter ECG, and CPET were performed. PVCs were analyzed for QRS duration, bundle branch block pattern, QRS axis, and coupling interval (CInt). For CPET, heart rate (HR), oxygen uptake (VO_2max), predicted VO_2max, and VO_2max expressed as a percentage of the predicted value (%VO₂) were measured.

RESULTS

In 37 patients (76%), arrhythmia subsided during exercise. Patients achieved lower VO_2max (32.9 ± 6.3 mL/min/kg) than controls (40.4 ± 6.7 mL/min/kg; P <.01). %VO₂ was 71.0 ± 13.7 in patients and 79.3 ± 12.2 in controls (P <.01). Exercise HR at which PVCs subsided correlated with VO_2max (r = 0.3; P = .07). Patients with persisting arrhythmia performed worse than those in whom arrhythmia subsided during exercise (VO_2max, P <.01; %VO_2,P <.01). No correlation between QRS and CInt parameters and VO_2max was observed.

CONCLUSION

Patients with PVCs have lower aerobic capacity than their healthy peers. Further worsening of exercise capacity is present when PVCs are preserved during effort.

Comparison of selective coronary angiography through the ablation catheter versus conventional coronary angiography to guide ablation of premature ventricular contractions originating from aortic cusp

BACKGROUND

Intraprocedural coronary angiography (CA) is recommended in patients undergoing ablation in aortic cusps to assess the relation of catheter tip and coronary ostia. In this report, we aimed to compare selective coronary angiography (SCA) through the contact force (CF)-sensing radiofrequency catheter with conventional coronary angiography (CCA) to guide ablation of premature ventricular contractions (PVC).

METHODS

This was a retrospective observational cohort study of prospectively collected data of 87 consecutive patients undergoing PVC ablation at a single institution between February 2016 and June 2021. Forty-six patients (53%) underwent SCA and forty-one patients (47%) underwent CCA. Data were consecutively collected case-by-case and entered into a computerized database. Procedural characteristics, complications, and clinical outcomes were compared between the SCA and CCA groups.

RESULTS

Successful ablation was achieved in seventy-seven (89%) patients. Total procedure and fluoroscopy time and radiation dose were significantly lower in SCA group (93 ± 22 min vs 102 ± 20 min, p = 0.042; 12 ± 3 min vs 14 ± 4 min, p = 0.030; 3292 ± 1221 μGy m² vs 3880 ± 1229 μGy m², p = 0.028, respectively). Median ambulation time was significantly longer in CCA group (6.8 ± 1 h vs 17.8 ± 1.8 h, p = 0.006).

CONCLUSIONS

Selective coronary angiography through the CF-sensing ablation catheter to assess the relation between the ablation site and the coronary ostia is feasible and safe. This technique precludes the requirement of an additional arterial access and decreases the total procedure and fluoroscopy time and radiation dose.

Premature Ventricular Contractions and Cardiomyopathy while on Ofatumumab for Treatment of Chronic Lymphocytic Leukaemia

Ofatumumab is a monoclonal antibody used in the treatment of recurrent and progressive chronic lymphocytic leukaemia (CLL) and was recently approved for the treatment of multiple sclerosis. We describe the case of a 68-year-old man who presented with complaints of irregular pulse readings while undergoing ofatumumab treatment for recurrent CLL. Electrocardiograms (ECGs) demonstrated premature ventricular contractions (PVCs) which eventually caused cardiomyopathy and failed to resolve despite ablative therapy. Ofatumumab-induced PVCs are confirmed in this case by the existence of documented PVCs on ECGs and the disappearance of these PVCs after the completion of ofatumumab treatment. To the best of our knowledge, there have been no previously reported cases of PVCs associated with ofatumumab in the literature.

LEARNING POINTS

Ofatumumab is a potential cause of arrhythmias and should be taken with care, particularly in individuals with underlying cardiac disease.Work-up of arrhythmias should include a comprehensive medication review as they can be caused by medications such as ofatumumab.

Intravascular lithotripsy for coronary calcium: A case report and review of the literature

BACKGROUND

Coronary calcium poses a challenge for the interventional cardiologist often leading to stent under-expansion and subsequent ischemic events. Aggressive balloon post-dilatation though helpful is usually inadequate. Multiple plaque ablation techniques are in vogue, but they are technically demanding and are not without complications. Shockwave intravascular lithotripsy (S-IVL) has emerged as a user-friendly and effective mechanism for calcium management with a high safety margin. A series of trials (DISRUPT CAD I-IV) have demonstrated both short-term and long-term safety and efficacy of the technique. As experience with the technique grows more and more, therapy areas like stent restenosis are being covered by the S-IVL.

CASE SUMMARY

We report a series of 2 cases successfully managed with S-IVL therapy at our center. The first case is of a 57-year-old smoker who presented with acute coronary syndrome. His left anterior descending coronary artery revealed calcified 90% stenosis on angiogram and a combination of superficial-deep calcium on intracoronary imaging. The calcium was treated with 20 pulses of S-IVL to create discontinuity and a sirolimus eluting drug-eluting stent was successfully implanted. The second case is that of an elderly lady who presented with stable angina and demonstrated diffuse calcified lesions in the left anterior descending artery on angiogram. She also demonstrated a mixture of superficial and deep seated calcium zones on imaging. S-IVL therapy was applied to generate fractures in calcium, and two overlapping drug-eluting stents were implanted successfully without any complications.

CONCLUSION

S-IVL is an emerging, efficient, user-friendly and safe therapy for managing intracoronary calcium in routine interventional practice.

Exacerbation of ventricular arrhythmias by continuous positive airway pressure treatment in idiopathic dilated cardiomyopathy

Continuous positive airway pressure (CPAP) therapy can be beneficial in patients with obstructive sleep apnea (OSA) and cardiovascular diseases, reducing arrhythmia frequency and improving cardiac function. We describe a case of moderate OSA with idiopathic dilated cardiomyopathy, in which the frequency of premature ventricular contraction (PVC) and non-sustained ventricular tachycardia (NSVT) increased immediately after initiating CPAP therapy. Although PVC and NSVT are benign cardiac arrhythmias, they are associated with an increased risk of sustained lethal ventricular tachyarrhythmias. Therefore, when initiating CPAP therapy, the possibility of increased arrhythmia should be considered.

Risk Factors and Heart Rate Variability Associated with Left Ventricular Enlargement in Patients with Frequent Premature Ventricular Contractions

INTRODUCTION

Premature ventricular contractions (PVCs) were now well recognized to carry the risk of inducing left ventricular (LV) enlargement and were closely related to the cardiac autonomic nervous activity quantified by heart rate variability (HRV) analysis. However, the relationship between LV enlargement and HRV in patients with frequent PVCs is still unclear. This study aimed to investigate the risk factors and HRV for LV enlargement in patients with frequent PVCs.

METHODS

Patients with frequent PVCs (n = 571), whose PVC burden counts >10,000/24 h or PVC burden >10%, were recruited. Patients were divided into LV enlargement group (n = 161), defined as female left ventricular end-diastolic diameter (LVEDD) >49.8 mm or male LVEDD >54.2 mm, and LV normal group (n = 410). Two groups were compared on their clinical, electrocardiographic, and HRV parameters. Logistic regression analysis was used to predict the risk factors of LV enlargement in patients with frequent PVCs. The parameters of echocardiography, Holter monitoring, and HRV were collected after ablation.

RESULTS

There were significant differences between the patients with left enlargement and with normal LV structure, in terms of sex, left ventricular ejection fraction (LVEF), level of N-terminal pro-brain natriuretic peptide (NT-proBNP), 24-h PVC burden, with nonsustained ventricular tachycardia, multifocal PVCs, QRS duration of PVC, and values of very low-frequency power of HRV parameter (all p < 0.05). Multivariate analysis showed that female gender (odds ratio [OR] = 2.753, p < 0.001), increased NT-proBNP (OR = 1.011, p = 0.022), increased LVEF (OR = 0.292, p < 0.001), increased 24-h PVC burden (OR = 1.594, p < 0.001), increased standard deviation of all NN intervals (SDNN) (OR = 1.100, p = 0.003), increased the proportion of consecutive NN intervals that differ by more than 50 ms (pNN50) (OR = 0.844, p = 0.026) were predictors for LV enlargement in patients with frequent PVCs. 84.4% (54/64) of patients with LV enlargement at baseline had normalized their LV structure after ablation. The values of SDNN, standard deviation of the averages of NN intervals in all 5-min segments, the square root of the mean of the sum of the squares of differences between adjacent NN intervals, pNN50, low-frequency power (LF), LF/high-frequency power ratio of patients were significantly decreased after ablation (all p < 0.05).

CONCLUSION

Female gender, increased level of NT-proBNP, lower LVEF, higher PVC burden, increased sympathetic parameters SDNN, and reduced parasympathetic parameters pNN50 were the independent risk factors of LV enlargement in patients with frequent PVCs. LV enlargement induced by PVCs can be reversible after PVC elimination by ablation. The activities of sympathetic and parasympathetic were reduced after ablation.

Adaptive support ventilation as an effective treatment option for central sleep apnea in an older adult with heart failure with preserved ejection fraction: a case report

Background

Adaptive support ventilation (ASV) is a proposed treatment option for central sleep apnea (CSA). Although the effectiveness of ASV remains unclear, some studies have reported promising results regarding the use of ASV in patients with heart failure with preserved ejection fraction (HfpEF). To illustrate the importance of suspecting and diagnosing sleep-disordered breathing (SDB) in older adults unable to recognize symptoms, we discuss a case in which ASV was effective in a patient with CSA and HfpEF, based on changes in the Holter electrocardiogram (ECG).

Case presentation.

An 82-year-old man presented to our hospital with vomiting on April 19, 2021. Approximately 10 years before admission, he was diagnosed with type 1 diabetes mellitus and recently required full support from his wife for daily activities due to cognitive dysfunction. Two days before admission, his wife was unable to administer insulin due to excessively high glucose levels, which were displayed as “high” on the patient’s glucose meter; therefore, we diagnosed the patient with diabetic ketoacidosis. After recovery, we initiated intensive insulin therapy for glycemic control. However, the patient exhibited excessive daytime sleepiness, and numerous premature ventricular contractions were observed on his ECG monitor despite the absence of hypoglycemia. As we suspected sleep-disordered breathing (SDB), we performed portable polysomnography (PSG), which revealed CSA. PSG revealed a central type of apnea and hypopnea due to an apnea–hypopnea index of 37.6, which was > 5. Moreover, the patient had daytime sleepiness; thus, we diagnosed him with CSA. We performed ASV and observed its effect using portable PSG and Holter ECG. His episodes of apnea and hypopnea were resolved, and an apparent improvement was confirmed through Holter ECG.

Conclusion

Medical staff should carefully monitor adult adults for signs of or risk factors for SDB to prevent serious complications. Future studies on ASV should focus on older patients with arrhythmia, as the prevalence of CSA may be underreported in this population and determine the effectiveness of ASV in patients with HfpEF, especially in older adults.

Conduction properties of the preferential pathway in a patient with idiopathic outflow ventricular arrhythmia

Ventricular arrhythmias (VA) originating from the outflow tract often conduct via a preferential pathway into a distant breakout site in the ventricular myocardium. Preferential pathway potentials, characterized as presystolic potentials preceding the QRS onset during VA and late potentials during sinus rhythm, are known targets of successful cardiac ablation. However, the mechanism of conduction and properties of the preferential pathway has not yet been fully elucidated. In the present case, we evaluated the conduction properties of the preferential pathway using 3D electrical mapping in a patient with VA originating from the left ventricular outflow tract. Similar to the embryonic cardiomyocyte, slow conduction velocity, decremental property, and automaticity were found in the preferential pathway. Thus, the preferential pathway may be considered a remnant of the developing conduction system as so-called “dead end tract,” rather than the typical structures such as the LV myocardium or Purkinje tissue.

Automated detection of premature ventricular contraction based on the improved gated recurrent unit network

BACKGROUND AND OBJECTIVE

Premature ventricular contraction (PVC) is the common arrhythmia disease, affecting thousands of individuals worldwide. However, the traditional PVC detection is cumbersome by visually inspecting electrocardiogram (ECG) signals.

METHODS

In this work, we specially propose an improved gated recurrent unit (IGRU) by setting a scale parameter into existing bidirectional GRU (BGRU) model for PVC signals recognition, which is used to alleviate the problem of information redundancy in BGRU. To verify the effectiveness, IGRU model will be embedded into a convolutional network frame and existing GRU and BGRU models are employed as control groups for a fair comparison.

RESULTS

The results exhibit that the model attains better model performance than control groups and several state-of-the-art algorithms with the accuracy of 98.3% and 97.9% with the MIT-BIH arrhythmia database and China Physiological Signal Challenge 2018 database. Besides, motivated from the waveform characteristics of ECG signals in PVC, the proposed model can provide certain physiological interpretability for physicians and researchers.

CONCLUSIONS

To our knowledge, this is the first attempt to re-design the existing GRU network for ECG signals classification, thus exhibiting great application potentials especially in lightweight equipment such as mobile phone and camera.

Short-coupled ventricular fibrillation represents a distinct phenotype among latent causes of unexplained cardiac arrest: a report from the CASPER registry

AIMS

The term idiopathic ventricular fibrillation (IVF) describes survivors of unexplained cardiac arrest (UCA) without a specific diagnosis after clinical and genetic testing. Previous reports have described a subset of IVF individuals with ventricular arrhythmia initiated by short-coupled trigger premature ventricular contractions (PVCs) for which the term short-coupled ventricular fibrillation (SCVF) has been proposed. The aim of this article is to establish the phenotype and frequency of SCVF in a large cohort of UCA survivors.

METHODS AND RESULTS

We performed a multicentre study including consecutive UCA survivors from the CASPER registry. Short-coupled ventricular fibrillation was defined as otherwise unexplained ventricular fibrillation initiated by a trigger PVC with a coupling interval of <350 ms. Among 364 UCA survivors, 24/364 (6.6%) met diagnostic criteria for SCVF. The diagnosis of SCVF was obtained in 19/24 (79%) individuals by documented ventricular fibrillation during follow-up. Ventricular arrhythmia was initiated by a mean PVC coupling interval of 274 ± 32 ms. Electrical storm occurred in 21% of SCVF probands but not in any UCA proband (P < 0.001). The median time to recurrent ventricular arrhythmia in SCVF was 31 months. Recurrent ventricular fibrillation resulted in quinidine administration in 12/24 SCVF (50%) with excellent arrhythmia control.

CONCLUSION

Short-coupled ventricular fibrillation is a distinct primary arrhythmia syndrome accounting for at least 6.6% of UCA. As documentation of ventricular fibrillation onset is necessary for the diagnosis, most cases are diagnosed at the time of recurrent arrhythmia, thus the true prevalence of SCVF remains still unknown. Quinidine is effective in SCVF and should be considered as first-line treatment for patients with recurrent episodes.

Impact of contact force sensing technology on outcome of catheter ablation of idiopathic pre-mature ventricular contractions originating from the outflow tracts

AIMS

Catheter ablation of frequent idiopathic pre-mature ventricular contractions (PVC) is increasingly performed. While potential benefits of contact force (CF)-sensing technology for atrial fibrillation ablation have been assessed in several studies, the impact of CF-sensing on ventricular arrhythmia ablation remains unknown. This study aimed to compare outcomes of idiopathic outflow tract PVC ablation when using standard ablation catheters as opposed to CF-sensing catheters.

METHODS AND RESULTS

In a retrospective multi-centre study, unselected patients undergoing catheter ablation of idiopathic outflow tract PVCs between 2013 and 2016 were enrolled. 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 24 h Holter ECG during follow-up. Overall, 218 patients were enrolled (median age 52 years, 51% males). Baseline and procedural data were similar in the standard ablation (24%) and the CF-sensing group (76%). Overall, the median PVC burden decreased from 21% (IQR 10-30%) before ablation to 0.2% (IQR 0-3.0%) after a median follow-up of 2.3 months (IQR 1.4-3.9 months). The rates of both acute (91% vs. 91%, P = 0.94) and sustained success (79% vs. 74%, P = 0.44) were similar in the standard ablation and the CF-sensing groups. No differences were observed in subgroups according to arrhythmia origin from the RVOT (65%) or LVOT (35%). Complications were rare (1.8%) and evenly distributed between the two groups.

CONCLUSION

The use of CF-sensing technology is not associated with increased success rate nor decreased complication rate in idiopathic outflow tract PVC ablation.

Post-extrasystolic potentiation as a predictor of premature ventricular contraction-cardiomyopathy in an animal model

AIMS

High premature ventricular contractions (PVCs) burden does not always predict the development of PVC-cardiomyopathy (CM). We sought to evaluate post-extrasystolic potentiation (PESP) of left ventricular ejection fraction (LVEF) to predict the severity of PVC-CM in an animal model.

METHODS AND RESULTS

Right ventricular apical bigeminal PVCs were introduced for 12 weeks in 11 canines to induce PVC-CM. Echocardiograms were performed to obtain LVEF without ectopy (Echo-1) and during PVCs (200 and 350 ms coupling intervals, Echo-2, and Echo-3, respectively), and premature atrial contractions (PACs) (Echo-4) at baseline and after 12 weeks of bigeminal PVCs. PESP was calculated as delta-LVEF between the sinus beat post-ectopy LVEF (Echo-2, -3, and -4, respectively) and LVEF without PVC (Echo-1) at baseline and 12 weeks of high PVC burden. A hyperdynamic LV function (LVEF > 70%) was noted in all animals only with early-coupled PVCs (LVEF at 200 ms: 74.4 ± 6%) at baseline. While PVC PESP at 200 ms had a strong significant correlation with the final 12-week LVEF (R = 0.8, P = 0.003), PVC PESP at 350 ms and PAC PESP had a positive but non-significant correlation (R = 0.53, P = 0.09, and R = 0.29, P = 0.34, respectively). Premature ventricular contraction PESP at 350 ms was significantly higher after PVC-CM had developed (delta-LVEF baseline 2.7 ± 2.9% vs. 12 weeks 18.6 ± 12.3% P < 0.001).

CONCLUSION

Bigeminal early-coupled PVCs cause hyperdynamic left ventricular function in the structurally normal canine heart due to PESP. The degree of PESP at baseline is inversely proportional to the PVC-CM severity at 12 weeks and maybe a predictor of PVC-CM as it may assess the myocardial adaptation reserve to PVCs.

Early clinical experience of radiofrequency catheter ablation using an audiovisual telesupport system

BACKGROUND

An audiovisual telesupport system that enables real-time audiovisual communications between 2 long-distance hospitals is one method of telemedicine. The usefulness and safety of radiofrequency catheter ablation (RFCA) using an audiovisual telesupport system has not been well established.

OBJECTIVE

The purpose of this study was to evaluate the effectiveness and safety of RFCA using an audiovisual telesupport system.

METHODS

An audiovisual telesupport system using a strictly secured virtual network was established between Kamisu Saiseikai Hospital (operator with 10 years' experience and 800 procedures) and the University of Tsukuba (advisor with >20 years' experience and 8000 procedures). We evaluated 19 initial consecutive patients who underwent RFCA using this system for tachyarrhythmia: 10 with atrial fibrillation (AF), 5 with paroxysmal supraventricular tachycardia (PSVT), 3 with premature ventricular contraction (PVC), and 1 with atrial flutter. Electrophysiological and procedural characteristics were retrospectively assessed.

RESULTS

Acute success was achieved in all 19 patients without any major complications, with the advisor's audiovisual assistance. Mean procedure time and fluoroscopic time were 161 ± 44 minutes and 24 ± 14 minutes for AF, 110 ± 17 minutes and 28 ± 8 minutes for PVC, and 132 ± 19 minutes and 32 ± 2 minutes for PSVT, respectively. There was no recurrence of clinical arrhythmia in 17 of the 19 patients (89%) during 13 ± 9 month follow-up.

CONCLUSION

An audiovisual telesupport system for RFCA is a useful and safe method that enabled the electrophysiologist with limited human resources to make an optimal decision regarding procedural strategy and endpoint with the remote advisor's audiovisual assistance.

Clinical and translational insights on premature ventricular contractions and PVC-induced cardiomyopathy

The medical community's understanding of the consequences of premature ventricular contractions (PVCs) and PVC-induced cardiomyopathy has been derived mostly from observational and large population-based studies. Due to the difficulty of predicting the development of PVC-cardiomyopathy, the acute and chronic cardiac effects of PVCs and the mechanism of PVC-cardiomyopathy have been derived from pre-clinical studies with large animal models. Recently, these studies have described myocardial substrates that could potentially increase morbidity and mortality in patients with frequent PVCs and PVC-cardiomyopathy. In this paper, we provide an up-to-date comprehensive review of these pre-clinical and clinical studies.

Cardiac afferent signaling partially underlies premature ventricular contraction-induced cardiomyopathy

BACKGROUND

The mechanisms underlying premature ventricular contraction (PVC)-induced cardiomyopathy (PIC) remain unknown. Transient receptor potential vanilloid-1 (TRPV1) afferent fibers are implicated in the reflex processing of cardiac stress.

OBJECTIVE

The purpose of this study was to determine whether cardiac TRPV1 afferent signaling promote PIC.

METHODS

A PIC swine model (50% PVC burden) was created via an implanted pacemaker. We selectively depleted cardiac TRPV1 afferent fibers using percutaneous epicardial application of resiniferatoxin (RTX). Animals were randomized to PVC only (n = 11), PVC+RTX (n = 11), or control (n = 6). We examined early-stage (4 weeks after implantation; n = 5) and late-stage PIC (8 weeks after implantation; n = 6). At terminal experimentation, animals underwent echocardiography, serum sampling, and physiological and autonomic reflex testing.

RESULTS

Depletion of cardiac TRPV1 afferents by RTX treatment was confirmed by absent sensory fibers and absent functional responses to TRPV1 activators. Left ventricular ejection fraction was worse in late-stage than early-stage PIC (P <.01). At 4 weeks (early stage), left ventricular ejection fraction was higher in PVC+RTX vs PVC animals (51.7% ± 1.6% vs 45.0% ± 2.1%; P = .030), whereas no significant difference between PVC and PVC+RTX was observed at 8 weeks (late stage). Histologic studies demonstrated reduced fibrosis in PVC+RTX vs PVC alone at 4 weeks (2.27% ± 0.14% vs 3.01% ± 0.21%; P = .020), suggesting that RTX mitigated profibrotic pathways induced by persistent PVCs.

CONCLUSION

TRPV1 afferent depletion alleviates left ventricular dysfunction in early- but not late-stage PIC. This temporal effect suggests that multiple pathways promote PIC, of which TRPV1 afferents are a part.

Eccentric hypertrophy in an animal model of mid- and long-term premature ventricular contraction-induced cardiomyopathy

BACKGROUND

Tachycardia and heart rate irregularity are proposed triggers of premature ventricular contraction-induced cardiomyopathy (PVC-cardiomyopathy). Bigeminal premature atrial and ventricular contractions (PACs and PVCs) increase heart rate and result in rhythm irregularities but differ in their effects on ventricular synchrony. Comparing chronic bigeminal PACs with PVCs would provide insights into mechanisms of PVC-cardiomyopathy.

OBJECTIVE

To compare the impact of chronic PACs and PVCs on ventricular hemodynamics, structure, and function.

METHODS

Pacemakers were implanted in 27 canines to reproduce atrial (PACs, n = 7) or ventricular bigeminy (PVCs, n = 11) for 12 weeks, and compared to sham-operated animals (n = 9). Four additional animals were exposed to long-term bigeminal PVCs (48 weeks). Hemodynamic changes were assessed using a pressure-transducing catheter at baseline and 12 weeks. Cardiac remodeling was monitored by transthoracic echocardiography throughout the 12- and 48-week protocols in the respective groups.

RESULTS

PVC group demonstrated a significant decrease in left ventricular (LV) ejection fraction and contractility (max dP/dt), impaired LV lusitropy (min dP/dt), and increase in LV dimensions and LV mass at 12 weeks without further deterioration beyond 16 weeks. Despite increased LV mass, relative wall thickness decreased, consistent with eccentric hypertrophy. No significant cardiac remodeling was noted in either sham or PAC groups at 12 weeks.

CONCLUSION

In contrast to bigeminal PACs, PVCs result in a cardiomyopathy characterized by reduced LV ejection fraction, LV dilation, and eccentric hypertrophy that plateaus between 12 and 16 weeks. The lack of remodeling in chronic PACs suggests that tachycardia and heart rate irregularity do not play a significant role on the development of PVC-cardiomyopathy.

Electrocardiographic features of arrhythmogenic right ventricular cardiomyopathy in school-aged children

It can be difficult to distinguish children with early-stage arrhythmogenic right ventricular cardiomyopathy (ARVC) from those with benign premature ventricular contraction (PVC). We retrospectively evaluated six school-aged children with ARVC and compared with those of 20 with benign PVC. The median age at initial presentation was 11.4 and 10.2 years in ARVC and benign PVC, respectively. None of the ARVC patients fulfilled the diagnostic criteria of ARVC at initial presentation. At ARVC diagnosis, the treadmill exercise test and Holter monitoring showed provoked PVC during exercise and pleomorphic PVC in all ARVC cases, respectively. During the observation period, terminal activation duration (TAD) was prolonged in all ARVC patients. In addition, ΔTAD (5.5 [3-10] ms) were significantly longer than those with benign PVC (p < 0.001). A new notched S-wave in V1 appeared in four (67%) ARVC patients, who had myocardial abnormalities in the right ventricle, and in zero benign PVC. Our electrocardiographic findings, such as provoked PVC during exercise, pleomorphic PVC, prolonged TAD, and a new notched S-wave in V1 could contribute to the early detection of ARVC in school-aged children.

A case of outflow tract premature ventricular contractions with very distant exit sites suspected to have a single origin

Outflow tract premature ventricular contractions sometimes demonstrate multiple exit sites in the right and left outflow tracts with preferential pathways. Here we present a case of outflow tract premature ventricular contractions, which were eliminated by ablation from the right ventricular outflow tract accompanied by additional ablation from the very distant endocardial left ventricular outflow tract. The findings during the ablation indicated there was a single origin with multiple exit sites rather than multiple origins for each QRS morphology. This case illustrates that the preferential pathways can demonstrate very distant multiple exit sites.

Left ventricular summit arrhythmias with an abrupt V3 transition: Anatomy of the aortic interleaflet triangle vantage point

BACKGROUND

While early precordial electrocardiographic (ECG) characteristics are useful to differentiate left-sided from the right-sided outflow tract ventricular arrhythmia (OTVA), few patterns predict an origin from the septal margin of the left ventricular (LV) summit.

OBJECTIVE

The purpose of this study was to report mapping and ablation characteristics of a new ECG pattern with left bundle branch morphology and an abrupt R-wave transition in lead V₃ (ATV3).

METHODS

Over a 3-year period, 78 consecutive patients (mean age 57±15 years; 35% female) with OTVA were referred for mapping and ablation. Twenty patients (26%) exhibited an ATV3 pattern, of whom 65% failed prior ablation.

RESULTS

Ninety-two percent of patients with ATV3 that underwent simultaneous epicardial and endocardial mapping demonstrated an intramural or epicardial site of origin. Eighty percent of OTVA with ATV3 was eliminated by ablation from the vantage point of the interleaflet triangle below the right-left coronary junction. The ATV3 pattern showed higher sensitivity, specificity, predictive value, and accuracy than validated ECG criteria (notch or "w" pattern in lead V₁, qrS pattern in leads V₁ through V₃, and pattern break V₂) for predicting successful ablation in the region of the anterior LV ostium. At 12±11 months, freedom from ventricular arrhythmia recurrence was 89% and 82% in the ATV3 and control groups, respectively.

CONCLUSION

ATV3 is a simple and distinct ECG pattern indicative of a site of origin from the septal margin of the LV summit. The right-left aortic interleaflet triangle vantage point was effective to eliminate OTVA with ATV3 that overwhelmingly exhibited the earliest activation from the epicardium or mid-myocardium. Test characteristics for ATV3 were superior to ECG patterns validated for the anterior LV ostium.

Evidence of 2 conduction exits of the moderator band: Findings from activation and pace mapping study

BACKGROUND

The moderator band (MB) is an endocavitary structure with only 2 exits to the bulk of the ventricular myocardium. Whether this may lead to specific electrophysiological characteristics remains unknown.

OBJECTIVE

The purpose of this study was to investigate electrocardiographic (ECG), activation, and pace mapping characteristics of MB-originated ventricular arrhythmias (VAs).

METHODS

Mapping and ablation of MB-VAs were performed in 12 patients under the guidance of a 3-dimensional electroanatomic mapping system and intracardiac echocardiography and ECG, and mapping data were analyzed. Of these patients, 11 underwent pace mapping study of 6 sites around the MB and the QRS morphology was compared.

RESULTS

The earliest activation site was free wall (FW) insertion in 8 patients (66.7%) and MB body in 4 patients (33.3%), preceding the QRS onset by 17.8±4.7 ms, and Purkinje-like potential was observed in 6 (50.0%). VAs were eliminated at the earliest activation site in the procedure, but recurrence was documented in 2 cases (16.7%) during a follow-up of 13.4±7.8 months. Pacing QRS complex from the MB was characterized by short QRS duration (P<.001), short intrinsicoid deflection time (P<.001), later precordial transition (P=.025), and notch on the descending limb of the inferior leads (P<.001) as compared with pacing from the adjacent anterior-lateral FW, and that notch could also differentiate MB from the anterior papillary muscle (P=.027). However, pacing QRS is identical between the MB body and the FW insertion in 11 of 11 patients and between the septal insertion and the MB body in 7 of 11 patients.

CONCLUSION

Bidirectional conduction via the 2 exits during MB-VAs contributed to distinct ECG and electrophysiological characteristics, while pace mapping is of limited value in defining the ablation target.

Clinical significance of premature ventricular contraction among adult patients: protocol for a scoping review

BACKGROUND

Premature ventricular contractions (PVCs) are one of the most common arrhythmias detected from electrocardiographic (ECG) monitoring. PVCs were thought to cause lethal arrhythmias and thus were closely monitored and treated. However, in current practice, PVCs generally do not required treatment. There is also concern that PVCs contribute to excessive alarms and lead to alarm fatigue. Practice guidelines for in-hospital monitoring state that monitoring for PVCs may be indicated on some patients but do not recommend continuous ECG monitoring. Despite these recommendations, PVC monitoring practices remain part of routine care, especially in the intensive care unit, for worry of missing potentially significant arrhythmia events. A thorough scoping review of the literature regarding the clinical significance of PVC is imperative, precisely to map out the evidence on the diagnostic and prognostic values of PVCs and to identify research gaps on this issue.

METHODS

The primary question of this review is "what is the clinical significance of PVCs in adults?" Preparation of this scoping review will use the PRISMA-P statement. A scoping review framework by Arksey and O'Malley will be adopted. In identifying relevant studies, the Population-Concept-Context (PCC) framework by the Joanna Briggs Institute will be used. A search strategy will be developed, and four major electronic databases will be searched: CINAHL, Embase, PubMed, and Web of Science Core Collection. Manual searches will also be conducted. The study selection process will adopt the 2009 PRISMA flow diagram. EndNote X8 will be used to manage citations, as well as for duplicates screening in addition to Microsoft Excel 2016. Two independent reviewers will assess potential studies in detail against inclusion criteria. A standardized data extraction form will be developed. Finally, critical appraisal will be conducted using a tool adapted from the Quality Appraisal Checklist by the National Institute for Health Care Excellence (NICE).

DISCUSSION

We believe this scoping review will provide a general foundation of evidence on the potential significance of PVCs concerning its diagnostic and prognostic value among the adult patient population. The findings will allow us to map out research gaps on this topic that could shape future research and ultimately clinical practice.

SCOPING REVIEW REGISTRATION

This scoping review has been registered in the Open Science Framework (OSF), DOI: https://doi.org/10.17605/OSF.IO/GAVT2 .