Ablation of typical atrial flutter using mini electrode measurements for maximum voltage-guided ablation: A randomized, controlled trial.

BACKGROUND: Novel ablation catheters with mini electrode (ME) sensing have become available but their utility is unclear. We investigated whether ablation of the cavotricuspid isthmus (CTI) for atrial flutter (AFL) would be improved using ME signals. METHODS: Sixty-one patients (76% male, 63 ± 10 years) with CTI-dependent AFL underwent ablation using a maximum voltage-guided approach, randomized to either standard 8 mm non-irrigated catheter with bipolar signals or IntellaTip MiFi catheter using ME signals alone. RESULTS: Acute bidirectional block was achieved in 97%. Mean follow-up was 16.7 ± 10 months. The median number of ablation lesions was 13 in both groups (range 3-62 vs. 1-43, p = .85). No significant differences were observed in AFL recurrences (17% vs. 11%, p = .7), median procedure durations (97 min [interquartile range (IQR), 71-121] vs. 87 min [IQR, 72-107], p = .55) or fluoroscopy times (31 min [IQR, 21-52] vs. 38 min [IQR, 25-70], p = .56). Amplitudes of ME signals were on average 160% greater than blinded bipolar signals. In 23.7% of lesions where bipolar signals were difficult to interpret, 13.6% showed a clear ME signal. CONCLUSIONS: There was no difference in the effectiveness of CTI ablation guided by ME signals, compared with using bipolar signals from a standard 8 mm ablation catheter. While ME signal amplitudes were larger and sometimes present when the bipolar signal was unclear, this did not improve procedural characteristics or outcomes. The results suggest future research should focus on lesion integrity rather than signal sensing.

Syncope, Epilepsy and Ictal Asystole: A Case Series and Narrative Review.

IMPORTANCE: Syncope is a common presentation to emergency departments, and cardiac and neurological aetiologies are the predominant causes. Ictal asystole is a rare cardio-neural phenomenon seen in epilepsy syndromes whereby a seizure causes asystole (≥3 s) leading to syncope. OBSERVATIONS: We present three cases of ictal asystole, together with a narrative review of the literature to assess the prevalence of the condition and review the pathophysiology, diagnosis and management. Our review of the literature has shown that ictal asystole is an unlikely contributor to sudden unexplained death in epilepsy (SUDEP). Pacemaker insertion may limit morbidity from trauma related to syncopal episodes but does not impact mortality. CONCLUSIONS AND RELEVANCE: Patients with ictal asystole should be diagnosed with concurrent electroencephalogram-electrocardiograph (EEG-ECG) monitoring, have their anti-epileptic drugs optimised and be considered for epilepsy surgery if feasible. The use of longer term ECG monitoring may be used as a diagnostic aid if ictal asystole is suspected. If there are ongoing syncopal episodes with associated ictal asystole ≥6 seconds, particularly despite medical therapy, a permanent pacemaker may be considered to reduce morbidity. Current guidelines should be updated to reflect the increasing knowledge of this condition.

The Prevalence of Pacing-Induced Cardiomyopathy (PICM) in Patients With Long Term Right Ventricular Pacing - Is it a Matter Of Definition?

BACKGROUND: Chronic right ventricular pacing may contribute to deterioration in left ventricular ejection fraction (LVEF). The aim of the study was to identify the prevalence of pacing-induced cardiomyopathy (PICM) in patients with chronic right ventricular pacing. METHODS: Patients attending a pacemaker clinic were retrospectively identified as having had transthoracic echocardiographic LVEF measurement during the 12 months prior to device implantation. Those with cardioverter-defibrillators or biventricular devices were excluded. The remaining patients were invited back for a repeat echocardiogram. Three (3) different definitions of PICM were employed: 1) follow-up LVEF of ≤40% if baseline LVEF was ≥50%, or an absolute reduction in LVEF ≥5% if baseline LVEF was <50%; 2) follow-up LVEF of ≤40% if baseline LVEF was ≥50%, or an absolute reduction in LVEF ≥10% if baseline LVEF was ≤50%; 3) absolute reduction in LVEF ≥10% irrespective of baseline LVEF. Alternate causes of cardiomyopathy were excluded following a chart review. RESULTS: The study cohort of 118 included 67 males (mean age 77.8±10.5years) and 51 females (mean age 76.8±11.2years). The mean time between baseline and follow-up echocardiograms was 3.5+1.4years (range 1.5-6.4 years). The prevalence of PICM ranged from 5.9 to 39.0% depending on PICM definition. Multivariate analysis found that PICM was significantly associated with ventricular pacing burden (p=0.013). CONCLUSIONS: The prevalence of pacing induced cardiomyopathy is dependent on current accepted clinical definitions. A clear definition of PICM is required for a better understanding of the clinical implications of right ventricular pacing.

Advances in atrioventricular and interventricular optimization of cardiac resynchronization therapy - what's the gold standard?

INTRODUCTION: Cardiac resynchronization therapy (CRT) is one of the most important advances in heart failure management in the last twenty years. Approximately one-third of patients appear not to respond to therapy. Although there are a number of possible mechanisms for non-response, an important factor is suboptimal atrioventricular (AV) and interventricular (VV) timing intervals. There remains controversy over whether routinely optimizing intervals is necessary and there is no agreed gold standard methodology. Optimization has classically been performed using echocardiography which has limits related to resource use, time-cost and variable reproducibility. Newer optimization methods using device-based sensors and algorithms show promise in reducing heart-failure hospitalization compared with echocardiography. Areas covered: This review outlines the rationale for optimization, the principles of AV and VV optimization, the standard echocardiographic approach and newer device-based algorithms and the evidence base for their use. Expert commentary: The incremental gains of optimization are likely to be real, but small, compared to the overall improvement gained from cardiac resynchronization itself. At this time routine optimization may not be mandatory but should be performed where there is no response to CRT. Device-based optimization algorithms appear to be practical and in some cases, deliver superior clinical outcomes compared to echocardiography.

Elective Cardioversion in the Era of Novel Oral Anticoagulants - Does a Nurse Administered Verbal Questionnaire for Compliance Negate the Need for Routine Transoesophageal Echocardiography?

BACKGROUND: Anticoagulation prior to elective external direct current cardioversion (EDCCV) is mandatory. The inability to monitor compliance with novel oral anticoagulants (NOACs) raises a potential safety issue. We aimed to evaluate whether a structured, nurse-led assessment of compliance prior to EDCCV ensures safety without the need for routine transoesophageal echocardiography (TOE). METHODS: Data was prospectively collected on consecutive patients undergoing EDCCV during 2014-2015. All procedures were supervised by an electrophysiology clinical nurse consultant (EPCNC). Drug compliance was verbally assessed using a standardised questionnaire by the EPCNC. Novel oral anticoagulants compliance was required for a continuous period of 3 weeks prior to EDCCV; otherwise a TOE-guided EDDCV was performed. All patients had follow-up 30 days post-procedure. RESULTS: Three hundred and eleven cardioversions were performed on 256 patients in whom 154 (49.5%) were prescribed a NOAC (rivaroxaban (n=105; 68.2%), dabigatran (n=38; 24.7%), apixaban (n=11; 7.1%)). Median age was 63 years (24-94 yrs), mean CHADS2-Vasc score was 2.0±1.5 and 138 (89.6%) were outpatients. One hundred and twenty-nine (83.8%) EDCCV were for atrial fibrillation and 25 (16.2%) for atrial flutter. Sinus rhythm was achieved in 90.3% of cases. Fourteen patients (9%) assessed as non-compliant underwent TOE. 129 (83.8%) EDCCV were performed without prior TOE. No stroke or systemic embolism was identified in any patient treated with either warfarin or a NOAC. CONCLUSIONS: A standardised, verbal questionnaire can be administered to detect NOAC non-compliance in patients undergoing EDCCV. With appropriate compliance assessment a nurse-led EDCCV without routine TOE did not significantly compromise safety in this study group.

Cardiac Sarcoidosis, Left Ventricular Impairment and Chronic Right Ventricular Pacing: Pacing or Pathology?

BACKGROUND: Cardiac sarcoidosis (CS) is an uncommon and under-recognised disease which most frequently presents with atrioventricular (AV) block and may also present with ventricular arrhythmias and left ventricular (LV) systolic dysfunction. Because of its protean clinical manifestations, confirming a diagnosis of CS is often challenging. METHODS: We report two cases where patients presented with atrioventricular (AV) block without evidence of underlying myocardial disease, underwent chronic dual-chamber pacing, and presented several years later with severe LV systolic dysfunction. RESULTS: Both patients were referred for assessment of pacing-induced cardiomyopathy with a view to upgrading their device to cardiac resynchronisation therapy (CRT). Subsequent investigation revealed features consistent with CS and appropriate immunosuppressive therapy resulted in improvement in LV function avoiding the requirement for CRT. CONCLUSION: We present a review of the diagnosis of cardiac sarcoidosis, the importance of imaging modalities and current treatment recommendations.

Surface ECG and Fluoroscopy are Not Predictive of Right Ventricular Septal Lead Position Compared to Cardiac CT.

BACKGROUND: Controversy exists regarding the optimal lead position for chronic right ventricular (RV) pacing. Placing a lead at the RV septum relies upon fluoroscopy assisted by a surface 12-lead electrocardiogram (ECG). We compared the postimplant lead position determined by ECG-gated multidetector contrast-enhanced computed tomography (MDCT) with the position derived from the surface 12-lead ECG. METHODS: Eighteen patients with permanent RV leads were prospectively enrolled. Leads were placed in the RV septum (RVS) in 10 and the RV apex (RVA) in eight using fluoroscopy with anteroposterior and left anterior oblique 30° views. All patients underwent MDCT imaging and paced ECG analysis. ECG criteria were: QRS duration; QRS axis; positive or negative net QRS amplitude in leads I, aVL, V1, and V6; presence of notching in the inferior leads; and transition point in precordial leads at or after V4. RESULTS: Of the 10 leads implanted in the RVS, computed tomography (CT) imaging revealed seven to be at the anterior RV wall, two at the anteroseptal junction, and one in the true septum. For the eight RVA leads, four were anterior, two septal, and two anteroseptal. All leads implanted in the RVS met at least one ECG criteria (median 3, range 1-6). However, no criteria were specific for septal position as judged by MDCT. Mean QRS duration was 160 ± 24 ms in the RVS group compared with 168 ± 14 ms for RVA pacing (P = 0.38). CONCLUSIONS: We conclude that the surface ECG is not sufficiently accurate to determine RV septal lead tip position compared to cardiac CT.

Using the Surface ECG to Identify Right Ventricular Pacing Lead Position: A Cautionary Tale.

Chronic right ventricular (RV) apical pacing may lead to the development of heart failure in some patients. Although pacing of the RV septum has been proposed as an alternative, positioning a lead in the true septum has proven challenging. In addition to fluoroscopy at implant, it has been suggested that 12-lead surface electrocardiogram (ECG) can be used to determine septal lead position; however, studies show this may be inaccurate. We present a case where a change in the ECG QRS axis late after pacemaker insertion with an active fixation lead highlights the difficulties of ECG localization of pacing leads.

Characteristics of Cavotricuspid Isthmus Ablation for Atrial Flutter Guided by Novel Parameters Using a Contact Force Catheter.

INTRODUCTION: This study sought to investigate specific contact force (CF) parameters to guide cavotricuspid isthmus (CTI) ablation and compare the outcome with a historical control cohort. METHODS AND RESULTS: Patients (30) undergoing CTI ablation were enrolled prospectively in the Study cohort and compared with a retrospective Control cohort of 30 patients. Ablation in the Study cohort was performed using CF parameters >10 g and <40 g and a Force Time Integral (FTI) of 800 ± 10 g. The Control cohort underwent traditionally guided CTI ablation. Traditional parameters (electrogram and impedance change) were assessed in both cohorts. All ablations regardless of achieving targets were included in data analysis. Bidirectional CTI block was achieved in all of the Study and 27 of the Control cohort. Atrial flutter recurred in 3 (10%) patients (follow-up 564 ± 212 days) in the study cohort and in 3 (10%) patients (follow-up 804 ± 540 days) in the Control cohort. There were no major complications in either cohort. Traditional parameters correlated poorly with CF parameters. In the Study cohort, flutter recurrence was associated with significantly lower FTI and ablation duration, but was not associated with total average CF. CONCLUSION: CTI ablation can be safely performed using CF parameters guiding ablation, with similar long-term results to a historical ablation control group. Potentially CF parameters may provide adjunctive information to enable a more efficient CTI ablation. Further research is required to confirm this.

Imaging and Right Ventricular Pacing Lead Position: A Comparison of CT, MRI, and Echocardiography.

BACKGROUND: Right ventricular nonapical (RVNA) pacing may reduce the risk of heart failure. Fluoroscopy is the standard approach to determine lead tip position, but is inaccurate. We compared cardiac computed tomography (CT), magnetic resonance imaging (MRI), two-dimensional and three-dimensional transthoracic echocardiography (TTE), and chest x-ray (CXR) to assess which provides the optimal assessment of right ventricular (RV) lead tip position. METHODS: Eighteen patients with MRI-conditional pacemakers (10 RVNA and eight apical [RVA] leads) underwent contrast CT, MRI, TTE, and a standard postimplant posteroanterior and lateral CXR. To compare images, the RV was arbitrarily partitioned into three long-axis segments (right ventricular outflow tract, middle, and apex), and two short-axis segments (septal and nonseptal). Agreement between modalities was assessed. RESULTS: RV lead tip position was identified in all patients on CT, TTE, and CXR, but was not identified in seven (39%) patients on MRI due to device-related artifact. Of 10 leads deemed to be nonapical/septal during implant, 70% were identified as nonapical on CXR, 60% on CT, 60% on MRI, and 80% on TTE. On CT imaging only 10% were truly septal, 20% on MRI, 30% on CXR, and 80% on TTE. Agreement was better between modalities when assessing position of the designated RVA leads. CONCLUSION: During implant leads intended for the septum are not confirmed as such on subsequent imaging, and marked heterogeneity is apparent between modalities. MRI is limited by artifact, and discrepancy exists between TTE and CT in identifying septal lead position. CT gave the clearest definition of lead tip position.

The Effect of Right Ventricular Apical and Nonapical Pacing on the Short- and Long-Term Changes in Left Ventricular Ejection Fraction: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials.

BACKGROUND: The right ventricular apex (RVA) is the traditional lead site for chronic pacing but in some patients may cause impaired left ventricular (LV) systolic function over time. Comparisons with right ventricular nonapical (RVNA) pacing sites have generated inconsistent results and recent meta-analyses have demonstrated unclear benefit due to heterogeneity across studies. METHODS AND RESULTS: A systematic search for randomized controlled trials that compared LV ejection fraction (LVEF) outcomes between RVNA and RVA pacing was performed up to October 2014. Twenty-four studies (n = 1,628 patients) met the inclusion criteria. To avoid between study heterogeneity two homogenous groups were created; group 1 where studies reported a difference (in favor of RVNA pacing) and group 2 where studies reported no difference between pacing sites. For group 1, weighted mean difference between RVNA and RVA pacing in terms of LVEF at follow-up was 5.40% (95% confidence interval [CI]: 3.94-6.87), related in part to group one's RVA arm demonstrating a significant reduction (mean loss -3.31%; 95% CI: -6.19 to -0.43) in LVEF between study baseline and end of follow-up. Neither of these finding were seen in group 2. Weighted regression modeling demonstrated that inclusion of poor baseline LVEF (<40%) in combination with greater than 12 months follow-up was three times more common in group 1 compared to group 2 (weighted relative risk 2.82; 95% CI: 1.03-7.72; P = 0.043). CONCLUSIONS: In patients requiring chronic right ventricular pacing where there is inclusion of impaired baseline LVEF (<40%), RVA pacing is associated with deterioration in LV function relative to RVNA pacing.

A comparison of right ventricular non-apical defibrillator lead position with traditional right ventricular apical position: a single centre experience.

BACKGROUND: Implantable cardioverter defibrillator (ICD) leads have traditionally been placed at the right ventricular apex (RVA). An important minority of patients with an ICD may develop a future requirement for bradycardia support. Pacing from the RVA may be detrimental, promoting heart failure and mortality. Increasingly non-apical right ventricular (RVNA) lead positions have been suggested as an alternative pacing site. METHODS: A retrospective review of 512 patients who received an ICD at our institution between 1999 and 2011 was conducted. A comparison of lead performance characteristics was performed between RVNA sites and those at RVA. Data were collated from chart review and the pacing database. RESULTS: The mean follow-up period in the RVNA cohort was 40.4±25.9 months and in the RVA cohort it was 38±31.8 months (p=0.43). The RVNA cohort consisted of 144 leads and 368 leads in the RVA cohort. The groups had similar baseline clinical characteristics. No significant difference was detected in the proportion of patients receiving an appropriate ICD defibrillation (RVNA 10.4% vs. RVA 16.8%; p=0.07), inappropriate defibrillation (RVNA 7.6% vs. RVA 7.6%; p=0.99) or an unsuccessful defibrillation (RVNA 0% vs. RVA 1.7%; p=0.12). There was also no significant difference in the proportion of patients receiving successful anti-tachycardia pacing (ATP) (RVNA 13.2% vs. RVA 17.4%; p=0.49) or failed ATP (RVNA 2.7% vs. RVA 4.1%; p=0.25). There was no significant difference in lead impedance (p=0.99), sensing (p=0.59) and pacing threshold (p=0.34). CONCLUSION: In this large retrospective study, RVNA ICD lead had similar stability and therapy efficacy compared to the traditional RVA position. This potentially has important implications for the suitability of RVNA as an alternative site for ICD leads.

Effect of right ventricular pacing lead site on left ventricular function in patients with high-grade atrioventricular block: results of the Protect-Pace study.

AIM: Chronic right ventricle (RV) apical (RVA) pacing is standard treatment for an atrioventricular (AV) block but may be deleterious to left ventricle (LV) systolic function. Previous clinical studies of non-apical pacing have produced conflicting results. The aim of this randomized, prospective, international, multicentre trial was to compare change in LV ejection fraction (LVEF) between right ventricular apical and high septal (RVHS) pacing over a 2-year study period. METHODS AND RESULTS: We randomized 240 patients (age 74 ± 11 years, 67% male) with a high-grade AV block requiring >90% ventricular pacing and preserved baseline LVEF >50%, to receive pacing at the RVA (n = 120) or RVHS (n = 120). At 2 years, LVEF decreased in both the RVA (57 ± 9 to 55 ± 9%, P = 0.047) and the RVHS groups (56 ± 10 to 54 ± 10%, P = 0.0003). However, there was no significant difference in intra-patient change in LVEF between confirmed RVA (n = 85) and RVHS (n = 83) lead position (P = 0.43). There were no significant differences in heart failure hospitalization, mortality, the burden of atrial fibrillation, or plasma brain natriutetic peptide levels between the two groups. A significantly greater time was required to place the lead in the RVHS position (70 ± 25 vs. 56 ± 24 min, P < 0.0001) with longer fluoroscopy times (11 ± 7 vs. 5 ± 4 min, P < 0.0001). CONCLUSION: In patients with a high-grade AV block and preserved LV function requiring a high percentage of ventricular pacing, RVHS pacing does not provide a protective effect on left ventricular function over RVA pacing in the first 2 years. PROTECT-PACE: ClinicalTrials.gov number NCT00461734.

Seven years experience of a nurse-led elective cardioversion service in a tertiary referral centre: an observational study.

BACKGROUND: Traditionally the provision of elective external direct current cardioversion (EDCCV) for patients with atrial arrhythmias has been doctor-led. Increasing demands on hospital beds and time pressures for doctors has driven the desire for an alternative approach. We established a nurse-led cardioversion service in 2006 and present our experience. METHODS: A prospective database of patients undergoing elective EDCCV between July 2006 and July 2013 was collected. Demographic data, arrhythmia, success and immediate complications of cardioversion were recorded. RESULTS: A total of 974 EDCCV were performed on 772 patients. The mean patient age was 62.7 years, 564 (73.1%) were male. In 530 patients (69.0%) AF was the primary arrhythmia, in 242 (31.0%) atrial flutter. All EDCCVs were performed in a high dependency unit. Sinus rhythm was obtained in 692 patients (89.6%). Of 640 outpatients, 629 (98.3%) were discharged on the same day of their procedure. Eleven patients (1.7%) required admission to hospital. No patients required urgent temporary transvenous or permanent pacing, and there were no deaths in association with this procedure. CONCLUSIONS: Nurse-led elective EDCCV is a safe and effective way of restoring sinus rhythm in patients with AF or atrial flutter, with additional benefits to resource provision.

An audit of amiodarone-induced thyrotoxicosis--do anti-thyroid drugs alone provide adequate treatment?

INTRODUCTION: Amiodarone is a widely used anti-arrhythmic drug. A common long-term complication is amiodarone-induced thyrotoxicosis (AIT). We examined retrospectively the efficacy of anti-thyroid drugs with or without prednisolone and the role of surgical thyroidectomy in the treatment of AIT in a single centre, in an iodine-replete region of Australia. METHODS: A retrospective audit of patients with AIT was performed between 2002-2012 at this centre. Twenty-seven patients, mean age 60.9 ± 2.3 years were identified. Medical therapy (anti-thyroid drugs, prednisolone) was commenced according to the treating endocrinologist. The main outcomes were time to euthyroidism and number proceeding to thyroidectomy. RESULTS: Of 11 patients commenced on anti-thyroid drugs alone, seven (64%) required the addition of prednisolone. Baseline free T4 was significantly higher in those ultimately treated with prednisolone (58.4 ± 6.3pmol/L) versus those not (31.7 ± 3.4pmol/L, P<0.05). Although similar results were seen with free T3, the difference was not significant (P=0.06). In patients with baseline free T4 <30pmol/L, 75% (3/4) achieved euthyroidism without prednisolone. Neither the use of prednisolone nor continuation of amiodarone significantly influenced time to euthyroidism. Eleven patients (41%) proceeded to surgical thyroidectomy, which was undertaken by an experienced surgical team without significant complications and no mortality. CONCLUSION: Patients with AIT generally required glucocorticoids. Mild disease (free T4 <30pmol/L) may be successfully treated with anti-thyroid drugs alone. Surgical thyroidectomy is a safe and effective treatment for those refractive to medical therapy.

A case of Lamin C gene-mutation with preserved systolic function and ventricular dysrrhythmia.

Lamin A/C gene-related cardiomyopathy is associated with progressive heart failure and malignant arrhythmias. Current guidelines advise the use of implantable defibrillators to prevent arrhythmogenic sudden cardiac death only in situations where there is evidence of severe left ventricular dysfunction. We describe a case of a woman with genetically confirmed Lamin C deficiency with preserved left ventricular function in whom an implantable defibrillator was inserted and within a month of implantation was used to terminate symptomatic ventricular tachycardia.