Convergent ablation for persistent atrial fibrillation: A UK multicentre perspective.

Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide and remains a major cause of morbidity and mortality. Unfortunately, a significant proportion of patients have persistent AF, for which conventional catheter ablation is less effective. However, convergent ablation has emerged in recent years as a hybrid treatment targeting both the epicardium and endocardium in a multidisciplinary joint cardiothoracic and electrophysiology procedure, with promising efficacy outcomes in recent studies. This treatment is increasingly being performed in the United Kingdom. This review article discusses the rationale and evidence behind convergent ablation, along with factors that need to be considered when setting up a successful ablation service.

Clinical study on antifungal drug resistance among cases of dermatophytosis in patients reporting to multiple tertiary care hospitals.

Background: In a tropical country like India, the warm and humid climate plays an important role in the increased incidence of superficial fungal infections. This is a study to identify the causative fungi of dermatophytosis and their in vitro antifungal susceptibility pattern among patients reporting to multiple tertiary care hospitals. Methods: Skin scrapping, nail clipping, and hair follicles were processed for microscopy, culture, and antifungal susceptibility testing as per standard guidelines. Antifungal susceptibility was performed as per published by Clinical Laboratory Standards Institute for yeasts (M27-A3) and filamentous fungi (M38-A2). Result: The study sample had a predominantly male population with the commonest age group being 21-30 years (39.57%) followed by 31-40 years (31.46%). Tinea corporis (57.30%) was the most common clinical presentation followed by tinea cruris (20.85%) and onychomycosis (14.73%). Microscopy positivity was 43.19%, while culture positivity was 23.97%. Dermatophytes accounted for the majority of isolates. All fungal isolates had high minimum inhibitory concentration (MIC) to fluconazole, suggesting that dermatophytes are possibly resistant to this drug. Conclusion: Trichophyton mentagrophytes is confirmed as the dominant pathogen of dermatophytosis in all three tertiary care hospitals.

Emerging evidence for a mechanistic link between low-frequency oscillation of ventricular repolarization measured from the electrocardiogram T-wave vector and arrhythmia.

Strong recent clinical evidence links the presence of prominent oscillations of ventricular repolarization in the low-frequency range (0.04-0.15 Hz) to the incidence of ventricular arrhythmia and sudden death in post-MI patients and patients with ischaemic and non-ischaemic cardiomyopathy. It has been proposed that these oscillations reflect oscillations of ventricular action potential duration at the sympathetic nerve frequency. Here we review emerging evidence to support that contention and provide insight into possible underlying mechanisms for this association.

Left ventricular rupture postradiofrequency catheter ablation: Transaortic, intraventricular patch exclusion repair.

Left ventricular (LV) rupture after radiofrequency catheter ablation (RFCA) is a rare but life-threatening complication. We describe a case of LV rupture secondary to RFCA successfully treated with a transaortic, intraventricular patch exclusion surgical repair, assisted by transoesophageal echocardiography and epicardial ultrasound assessment. Patch exclusion technique can offer a physiological repair with better preservation of myocardial mechanical characteristics and possibly less damage to healthy myocardium and surrounding structures.

Convergence of Epicardial and Endocardial RF Ablation for the Treatment of Symptomatic Persistent AF (CONVERGE Trial): Rationale and design.

Atrial fibrillation is the most common sustained arrhythmia affecting over 33 million people worldwide. Approximately 70% of AF patients have non-paroxysmal AF. As AF progresses from paroxysmal to non-paroxysmal forms, the prevalence of comorbidities increases. The efficacy of catheter ablation for persistent and long standing persistent (LSP) AF is <40%, often requiring multiple ablation procedures with greater cost and potentially more complications. There is an unmet need to effectively treat such patients. METHODS: CONVERGE is an investigational device exempt, prospective, multi-center, open label 2:1 randomized controlled pivotal study to evaluate the overall success of the Convergent hybrid procedure compared to endocardial catheter ablation for the treatment of symptomatic persistent AF refractory or intolerant to at least one Class I and /or III anti-arrhythmic drug (AAD). A total of 153 subjects at 27 centers are treated in the study. The CONVERGE study is differentiated from other studies currently being conducted on the persistent AF population, because a) there is no time restriction on the duration of diagnosed AF in the patients being studied and b) the trial allows patients with left atrial sizes up to 6 centimeters. The ongoing trials are limited to either 6 months, 12 months or 3-years of continuous AF making CONVERGE the only ablation trial thus far to include a substantial portion of patients with longstanding persistent AF. The convergent procedure involves combination of minimally invasive pericardioscopic epicardial ablation with endocardial left atrial ablation. The primary endpoint is freedom from AF/AFL/AF absent class I/III AAD, except for a previously failed class I/ III AAD with no increase in dosage following 3-months through 12-months. The primary safety endpoint is the incidence of major adverse events from the procedure through 30-days post procedure. CONCLUSION: CONVERGE AF compares the overall success of the Convergent hybrid procedure to endocardial catheter ablation for the treatment of persistent and longstanding persistent AF. By providing objective comparative data, the study aims to provide guidance on the treatment of such patients.

Transvenous lead extraction in patients with cardiac resynchronization therapy devices is not associated with increased 30-day mortality.

AIMS: Transvenous lead extraction (TLE) may be necessary due to system infection/erosion or lead malfunction. Cardiac resynchronization therapy (CRT) patients undergoing TLE may be at greater risk due to increased comorbidities. We examined whether patients with CRT systems undergoing TLE had more comorbidities and higher 30-day mortality than those with non-CRT devices. METHODS AND RESULTS: All TLEs between October 2000 and December 2016 were prospectively collected. During this period 925 TLEs occurred (CRT group 231, non-CRT group 694). Cardiac resynchronization therapy patients were older (68.1 ± 10.8 years vs. 64.3 ± 16.1 years, P = 0.024); more likely male (85.7% vs. 69%, P < 0.001); had lower mean left ventricular ejection fraction (34.1 ± 12.7% vs. 48.3 ± 12.9%, P < 0.001); had higher prevalence of renal impairment (33.8% vs. 13.7%, P < 0.001) and were more likely to have ≥2 comorbidities (84% vs. 40.1%, P < 0.001). Mean lead dwell time was lower in the CRT group (5.6 ± 5.5 years vs. 7.6 ± 7.1 years, P = 0.002). There was no significant difference in all-cause 30-day mortality rates between CRT (3.0%, n = 7) and non-CRT patients (2.0%, n = 14) (P = 0.443). The majority of deaths in both groups were due to sepsis. Univariate and multivariate analysis showed age, renal impairment and sepsis were associated with increased risk of 30-day mortality. Transvenous lead extraction of a CRT system did not predict 30-day mortality. CONCLUSION: Transvenous lead extraction in CRT patients was not associated with increased 30-day mortality when compared with non-CRT patients. Age, renal impairment and sepsis were independent predictors of 30-day mortality. Sepsis was the main cause of 30-day mortality.

Predictors of mortality and outcomes in transvenous lead extraction for systemic and local infection cohorts.

BACKGROUND: Transvenous lead extraction (TLE) may be necessary due to infective and noninfective indications. We aim to identify predictors of 30-day mortality and risk factors between infective versus noninfective groups and systemic versus local infection subgroups. METHODS: A total of 925 TLEs between October 2000 and December 2016 were prospectively collected and dichotomized (infective group n = 505 vs noninfective group n = 420 and systemic infection n = 164 vs local infection n = 341). RESULTS: All-cause major complication including deaths was significantly higher (5.1%, n = 26 vs 1.2%, n = 5, P = 0.001) as well as 30-day mortality (4.0%, n = 20 vs 0.2%, n = 1, P < 0.001) in the infective group compared to the noninfective group. Both subgroups (systemic vs local infection) were balanced for demographics. All-cause major complication including deaths was significantly higher (9.1%, n = 15 vs 3.2%, n = 11, P = 0.008) as well as all-cause 30-day mortality (7.9%, n  = 13 vs 2.1%, n = 7, P = 0.003) in the systemic infection subgroup compared to the local infection subgroup. CONCLUSION: Patients undergoing TLE for infective indications are at greater risk of 30-day all-cause mortality compared to noninfective patients. Patients undergoing TLE for systemic infective indications are at greater risk of 30-day all-cause mortality compared to patients with local infection. Renal impairment, systemic infection, and elevated preprocedure C-reactive protein are independent predictors of 30-day all-cause mortality in patients undergoing TLE for an infective indication.

Prolonged lead dwell time and lead burden predict bailout transfemoral lead extraction.

BACKGROUND: Transvenous lead extraction (TLE) may be performed by superior approach using the original implant vein or via a femoral approach; however, limited comparative data exists. We compare outcomes between femoral versus nonfemoral TLE approaches and determine predictors of bailout transfemoral lead extraction in patients undergoing initial TLE via the original implant vein by a superior approach. METHODS: All consecutive TLEs between October 2000 and March 2018 were prospectively collected (n = 1052). Patients were dichotomized into femoral (n = 118) and nonfemoral (n = 934) groups. RESULTS: Demographics were balanced between femoral vs nonfemoral groups. Patients in the femoral group had significantly higher mean lead dwell times (11.6 ± 9.7 vs 6.6 ± 6.6 years, P < .001), mean number of leads extracted (2.7 ± 1.3 vs 2.0 ± 1.0, P < .001), 30-day procedure related major complications (including deaths) (8.5% vs 1.1%, P < .001) and emergency thoracotomy rates (4.2% vs 0.7%, P = .007). All-cause 30-day mortality rates were similar between groups (3.4% vs 2.0%, P = .315). Prolonged lead dwell time and increased number of leads extracted were predictive of a bailout transfemoral approach at multivariable analysis. CONCLUSION: Femoral approach TLE is associated with increased risk of 30-day procedure related major complications but not 30-day all-cause mortality. Prolonged lead dwell time and increased number of leads extracted are independent predictors for bailout transfemoral lead extraction. Such patients should be considered high risk of major complications and performed by high-volume lead extraction centers with experience in multiple approaches and techniques including experience with transfemoral lead extraction.

Predictors and outcomes of patients requiring repeat transvenous lead extraction of pacemaker and defibrillator leads.

BACKGROUND: A proportion of patients who undergo an initial lead extraction procedure will require a second, repeat extraction. Data regarding this clinical entity are scarce and neither the predisposing risk factors for, nor outcomes from, these procedures have been described previously. We sought to determine the incidence, risk factors, and outcomes of repeat lead extraction. METHODS: A database of extraction procedures from 2001 to 2015 was analyzed. Repeat extraction procedures were identified and the indication for extraction was dichotomized into infection and lead-related problems. Univariate and multivariate analyses were performed to identify predictors of repeat extraction. RESULTS: 807 extraction procedures were identified in 755 patients of whom 6% required a repeat extraction. At multivariate analysis, only suffering a major complication at the initial extraction procedure (odds ratio [OR] 21.5, 95% confidence interval [CI] 2.69-171.92; P < 0.01), complexity of device (cardiac resynchronization devices/implantable cardioverter defibrillators) (OR 2.58, 95% CI 1.2-5.2; P = 0.01), and age (OR 1.02 per year, 95% CI 1.0-1.4; P  =  0.03) were significant predictors of repeat extraction. When repeat extraction was required for infection there was a significant increase in mortality compared with those who did not require a second procedure (36% vs 23%; P  =  0.02). CONCLUSIONS: Repeat lead extraction is required in 6% of cases. Complexity of device, age at extraction, and a major complication at the first extraction were predictors of repeat extraction. Mortality is significantly increased where the repeat procedure is for infection. Clinicians should alert patients to the potential need for further extraction and the increased risks of repeat procedures when indicated for infection.

The effect of activation rate on left atrial bipolar voltage in patients with paroxysmal atrial fibrillation.

INTRODUCTION: Bipolar voltage is used during electroanatomic mapping to define abnormal myocardium, but the effect of activation rate on bipolar voltage is not known. We hypothesized that bipolar voltage may change in response to activation rate. By examining corresponding unipolar signals we sought to determine the mechanisms of such changes. METHODS AND RESULTS: LA extrastimulus mapping was performed during CS pacing in 10 patients undergoing first time paroxysmal atrial fibrillation ablation. Bipolar and unipolar electrograms were recorded using a PentaRay catheter (4-4-4 spacing) and indifferent IVC electrode, respectively. An S1S2 pacing protocol was delivered with extrastimulus coupling interval reducing from 350 to 200 milliseconds. At each recording site (119 ± 37 per LA), bipolar peak-to-peak voltage, unipolar peak to peak voltage and activation delay between unipole pairs was measured. Four patterns of bipolar voltage/extrastimulus coupling interval curves were seen: voltage attenuation with plateau voltage >1 mV (48 ± 15%) or <1 mV (22 ± 15%), and voltage unaffected by coupling interval with plateau voltage >1 mV (17 ± 10%) or <1 mV (13 ± 8%). Electrograms showing bipolar voltage attenuation were associated with significantly greater unipolar voltage attenuation at low (25 ± 28 mV/s vs. 9 ± 11 mV/s) and high (23 ± 29 mV/s vs. 6 ± 12 mV/s) plateau voltage sites (P < 0.001). There was a small but significant increase in conduction delay between unipole pairs at sites showing bipolar voltage attenuation (P = 0.026). CONCLUSIONS: Bipolar electrogram voltage is dependent on activation rate at a significant proportion of sites. Changes in unipolar voltage and timing underlie these effects. These observations have important implications for use of voltage mapping to delineate abnormal atrial substrate.

Substrate-dependent risk stratification for implantable cardioverter defibrillator therapies using cardiac magnetic resonance imaging: The importance of T1 mapping in nonischemic patients.

INTRODUCTION: The role of implantable cardioverter defibrillators (ICDs) in nonischemic cardiomyopathy is unclear and better risk-stratification is required. We sought to determine if T1 mapping predicts appropriate defibrillator therapy in patients with nonischemic cardiomyopathy. We studied a mixed cohort of ischemic and nonischemic patients to determine whether different cardiac magnetic resonance (CMR) applications (T1 mapping, late gadolinium enhancement, and Grayzone) were selectively predictive of therapies for the different arrhythmic substrates. METHODS AND RESULTS: We undertook a prospective longitudinal study of consecutive patients receiving defibrillators in a tertiary cardiac center. Participants underwent CMR myocardial tissue characterization using T1 mapping and conventional CMR scar assessment before device implantation. QRS duration and fragmentation on the surface electrocardiogram were also assessed. The primary endpoint was appropriate defibrillator therapy. One-hundred thirty patients were followed up for a median of 31 months (IQR ± 9 months). In nonischemic patients, T1_native was the sole predictor of the primary endpoint (hazard ratio [HR] 1.12 per 10 millisecond increment in value [95% confidence interval [CI] 1.04-1.21; P ≤ 0.01]). In ischemic patients, Grayzone_2SD-3SD was the strongest predictor of appropriate therapy (HR 1.34 per 1% left ventricular increment in value [95% CI 1.03-1.76; P = 0.03]). QRS fragmentation correlated well with myocardial scar core (receiver operating characteristic area under the curve [ROC AUC] 0.64; P = 0.02) but poorly with T1_native (ROC AUC 0.4) and did not predict appropriate therapy. CONCLUSIONS: In the medium-long term, T1_native mapping was the only independent predictor of therapy in nonischemic patients, whereas Grayzone was a better predictor in ischemic patients. These findings suggest a potential role for T1_native mapping in the selection of patients for ICDs in a nonischemic population.

Diagnosis and management of iatrogenic cardiac perforation caused by pacemaker and defibrillator leads.

AIMS: Cardiac perforations caused by pacemaker or implantable cardioverter-defibrillator (ICD) leads are uncommon but potentially fatal events. The optimal approach to such cases is unclear. The aim of this study was to identify the optimal imaging modality and management strategy for cardiac perforation. METHODS AND RESULTS: All patients presenting to a single institution with cardiac perforation >24 h since implant between 2011 and 2015 were identified retrospectively. Assessment of the diagnostic performance of pre-extraction chest radiography, transthoracic echocardiography (TTE), and computed tomography (CT) was carried out by blinded review. The method of lead extraction and any associated complications were examined. Eighteen cases of cardiac perforation were identified from 426 lead extraction procedures. Sixteen patients had abnormal electrical parameters at device interrogation. In all cases, the perforating lead was an active fixation model, and in four cases, this was an ICD coil. The accuracy of CT imaging for the diagnosis of cardiac perforation was 92.9%, with sensitivity and specificity of 100 and 85.7%, respectively. This was superior to both TTE (accuracy 62.7%, sensitivity and specificity 41.2 and 84.2%, respectively) and chest radiography (accuracy 61.1%, sensitivity and specificity 27.7 and 94.4%, respectively). Transvenous lead extraction (TLE) was performed in 17 patients, and a hybrid surgical approach in 1 patient. Of those who underwent TLE, there was 100% complete procedural success as per Heart Rhythm Society definitions. CONCLUSION: In the setting of cardiac perforation, CT is the imaging modality of choice. Transvenous lead extraction can be recommended as a safe, efficacious, and versatile intervention.

Biophysical Modeling Predicts Ventricular Tachycardia Inducibility and Circuit Morphology: A Combined Clinical Validation and Computer Modeling Approach.

INTRODUCTION: Computational modeling of cardiac arrhythmogenesis and arrhythmia maintenance has made a significant contribution to the understanding of the underlying mechanisms of arrhythmia. We hypothesized that a cardiac model using personalized electro-anatomical parameters could define the underlying ventricular tachycardia (VT) substrate and predict reentrant VT circuits. We used a combined modeling and clinical approach in order to validate the concept. METHODS AND RESULTS: Non-contact electroanatomic mapping studies were performed in 7 patients (5 ischemics, 2 non-ischemics). Three ischemic cardiomyopathy patients underwent a clinical VT stimulation study. Anatomical information was obtained from cardiac magnetic resonance imaging (CMR) including high-resolution scar imaging. A simplified biophysical mono-domain action potential model personalized with the patients' anatomical and electrical information was used to perform in silico VT stimulation studies for comparison. The personalized in silico VT stimulations were able to predict VT inducibility as well as the macroscopic characteristics of the VT circuits in patients who had clinical VT stimulation studies. The patients with positive clinical VT stimulation studies had wider distribution of action potential duration restitution curve (APD-RC) slopes and APDs than the patient with a negative VT stimulation study. The exit points of reentrant VT circuits encompassed a higher percentage of the maximum APD-RC slope compared to the scar and non-scar areas, 32%, 4%, and 0.2%, respectively. CONCLUSIONS: VT stimulation studies can be simulated in silico using a personalized biophysical cardiac model. Myocardial spatial heterogeneity of APD restitution properties and conductivity may help predict the location of crucial entry/exit points of reentrant VT circuits.

Focal But Not Diffuse Myocardial Fibrosis Burden Quantification Using Cardiac Magnetic Resonance Imaging Predicts Left Ventricular Reverse Modeling Following Cardiac Resynchronization Therapy.

INTRODUCTION: Many heart failure patients with dyssynchrony do not reverse remodel (RR) in response to cardiac resynchronization therapy (CRT). The presence of focal and diffuse interstitial myocardial fibrosis may explain this high nonresponse rate. T1 mapping is a new cardiac magnetic resonance imaging (CMR) technique that overcomes the limitations of conventional contrast CMR and provides reliable quantitative assessment of diffuse myocardial fibrosis. The study tested the hypothesis that focal and diffuse fibrosis quantification would correlate with a lack of left ventricular (LV) RR to CRT. METHODS AND RESULTS: In a prospective study of 48 consecutive patients (27 ischemic cardiomyopathy, 21 dilated cardiomyopathy) LV scar burdens were quantified (scar core and gray zone using late gadolinium enhancement LGE CMR; interstitial fibrosis using T1 mapping) before CRT implant. LV RR was defined by a ≥ 15% reduction in LV end-systolic volume 6 months postimplant. Twenty-seven (56%) patients were responders with RR. Association between scar quantification and LV RR was assessed using the Poisson regression model. Univariate analysis showed that QRS duration/morphology, scar core, and gray zone volumes expressed as % of LV mass and extracellular volume index (ECV) (a measure of interstitial fibrosis from T1 mapping) to be significant predictors of LV RR. Multivariable-adjusted analyses demonstrated scar core quantification (≥ 13.7% LV mass) to be the only independent predictor of LV RR (prevalence ratio 0.40, P = 0.038). CONCLUSIONS: Focal scar burden detected by LGE CMR is associated with a poor response to CRT. Diffuse interstitial fibrosis assessment by T1 mapping, however, is not independently predictive of CRT response.

Improvement of Right Ventricular Hemodynamics with Left Ventricular Endocardial Pacing during Cardiac Resynchronization Therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) with biventricular epicardial (BV-CS) or endocardial left ventricular (LV) stimulation (BV-EN) improves LV hemodynamics. The effect of CRT on right ventricular function is less clear, particularly for BV-EN. Our objective was to compare the simultaneous acute hemodynamic response (AHR) of the right and left ventricles (RV and LV) with BV-CS and BV-EN in order to determine the optimal mode of CRT delivery. METHODS: Nine patients with previously implanted CRT devices successfully underwent a temporary pacing study. Pressure wires measured the simultaneous AHR in both ventricles during different pacing protocols. Conventional epicardial CRT was delivered in LV-only (LV-CS) and BV-CS configurations and compared with BV-EN pacing in multiple locations using a roving decapolar catheter. RESULTS: Best BV-EN (optimal AHR of all LV endocardial pacing sites) produced a significantly greater RV AHR compared with LV-CS and BV-CS pacing (P < 0.05). RV AHR had a significantly increased standard deviation compared to LV AHR (P < 0.05) with a weak correlation between RV and LV AHR (Spearman rs = -0.06). Compromised biventricular optimization, whereby RV AHR was increased at the expense of a smaller decrease in LV AHR, was achieved in 56% of cases, all with BV-EN pacing. CONCLUSIONS: BV-EN pacing produces significant increases in both LV and RV AHR, above that achievable with conventional epicardial pacing. RV AHR cannot be used as a surrogate for optimizing LV AHR; however, compromised biventricular optimization is possible. The beneficial effect of endocardial LV pacing on RV function may have important clinical benefits beyond conventional CRT.

Effect of autonomic blocking agents on the respiratory-related oscillations of ventricular action potential duration in humans.

Ventricular action potential duration (APD) is an important component of many physiological functions including arrhythmogenesis. APD oscillations have recently been reported in humans at the respiratory frequency. This study investigates the contribution of the autonomic nervous system to these oscillations. In 10 patients undergoing treatment for supraventricular arrhythmias, activation recovery intervals (ARI; a conventional surrogate for APD) were measured from multiple left and right ventricular (RV) endocardial sites, together with femoral artery pressure. Respiration was voluntarily regulated and heart rate clamped by RV pacing. Sympathetic and parasympathetic blockade was achieved using intravenous metoprolol and atropine, respectively. Metroprolol reduced the rate of pressure development (maximal change in pressure over time): 1,271 (± 646) vs. 930 (± 433) mmHg/s; P < 0.01. Systolic blood pressure (SBP) showed a trend to decrease after metoprolol, 133 (± 21) vs. 128 (± 25) mmHg; P = 0.06, and atropine infusion, 122 (± 26) mmHg; P < 0.05. ARI and SBP exhibited significant cyclical variations (P < 0.05) with respiration in all subjects with peak-to-peak amplitudes ranging between 0.7 and 17.0 mmHg and 1 and 16 ms, respectively. Infusion of metoprolol reduced the mean peak-to-peak amplitude [ARI, 6.2 (± 1.4) vs. 4.4 (± 1.0) ms, P = 0.008; SBP, 8.4 (± 1.6) vs. 6.2 (± 2.0) mmHg, P = 0.002]. The addition of atropine had no significant effect. ARI, SBP, and respiration showed significant coupling (P < 0.05) at the breathing frequency in all subjects. Directed coherence from respiration to ARI was high and reduced after metoprolol infusion [0.70 (± 0.17) vs. 0.50 (± 0.23); P < 0.05]. These results suggest a role of respiration in modulating the electrophysiology of ventricular myocardium in humans, which is partly, but not totally, mediated by ß-adrenergic mechanisms.

A randomized prospective mechanistic cardiac magnetic resonance study correlating catheter stability, late gadolinium enhancement and 3 year clinical outcomes in robotically assisted vs. standard catheter ablation.

AIMS: To prospectively compare cardiac magnetic resonance late gadolinium enhancement (LGE) findings created by standard vs. robotically assisted catheter ablation lesions and correlate these with clinical outcomes. METHODS AND RESULTS: Forty paroxysmal atrial fibrillation patients (mean age 54 ± 13.8 years) undergoing first left atrial ablation were randomized to either robotic-assisted navigation (Hansen Sensei(®) X) or standard navigation. Pre-procedural, acute (24 h post-procedure) and late (beyond 3 months) scans were performed with LGE and T2W imaging sequences and percentage circumferential enhancement around the pulmonary vein (PV) antra were quantified. Baseline pre-procedural enhancements were similar in both groups. On acute imaging, mean % encirclements by LGE and T2W signal were 72% and 80% in the robotic group vs. 60% (P = 0.002) and 76%(P = 0.45) for standard ablation. On late imaging, the T2W signal resolved to baseline in both groups. Late gadolinium enhancement remained the predominant signal with 56% encirclement in the robotic group vs. 45% in the standard group (P = 0.04). At 6 months follow-up, arrhythmia-free patients had an almost similar mean LGE encirclement (robotic 64%, standard 60%, P = 0.45) but in recurrences, LGE was higher in the robotic group (43% vs. 30%, P = 0.001). At mean 3 years follow-up, 1.3 procedures were performed in the robotic group compared with 1.9 (P < 0.001) in the standard to achieve a success rate of 80% vs. 75%. CONCLUSION: Robotically assisted ablation results in greater LGE around the PV antrum. Effective lesions created through improved catheter stability and contact force during initial treatment may have a role in reducing subsequent re-do procedures.

Cardiac magnetic resonance and electroanatomical mapping of acute and chronic atrial ablation injury: a histological validation study.

AIMS: To provide a comprehensive histopathological validation of cardiac magnetic resonance (CMR) and endocardial voltage mapping of acute and chronic atrial ablation injury. METHODS AND RESULTS: 16 pigs underwent pre-ablation T2-weighted (T2W) and late gadolinium enhancement (LGE) CMR and high-density voltage mapping of the right atrium (RA) and both were repeated after intercaval linear radiofrequency ablation. Eight pigs were sacrificed following the procedure for pathological examination. A further eight pigs were recovered for 8 weeks, before chronic CMR, repeat RA voltage mapping and pathological examination. Signal intensity (SI) thresholds from 0 to 15 SD above a reference SI were used to segment the RA in CMR images and segmentations compared with real lesion volumes. The SI thresholds that best approximated histological volumes were 2.3 SD for LGE post-ablation, 14.5 SD for T2W post-ablation and 3.3 SD for LGE chronically. T2-weighted chronically always underestimated lesion volume. Acute histology showed transmural injury with coagulative necrosis. Chronic histology showed transmural fibrous scar. The mean voltage at the centre of the ablation line was 3.3 mV pre-ablation, 0.6 mV immediately post-ablation, and 0.3 mV chronically. CONCLUSION: This study presents the first histopathological validation of CMR and endocardial voltage mapping to define acute and chronic atrial ablation injury, including SI thresholds that best match histological lesion volumes. An understanding of these thresholds may allow a more informed assessment of the underlying atrial substrate immediately after ablation and before repeat catheter ablation for atrial arrhythmias.

Positive response to cardiac resynchronization therapy reduces arrhythmic events after elective generator change in patients with primary prevention CRT-D.

INTRODUCTION: Cardiac resynchronization therapy (CRT) and implantable cardioverter-defibrillators (ICD) are effective therapies for heart failure (HF) patients with cardiac dyssynchrony. Patients receiving primary prevention CRT-defibrillator that positively remodel might no longer qualify for ICD indication due to CRT-induced left ventricular ejection fraction (LVEF) improvement. We aimed to evaluate the outcome of CRT-D patients at the time of device replacement (DR). METHODS AND RESULTS: Patients undergoing primary prevention CRT-D DR were prospectively included from November 2007 to March 2011 in 2 centers. CRT response was as defined as ≥1 NYHA class improvement and an increase in LVEF ≥10%. Before DR, all patients underwent echocardiography and device interrogation. Patients without theoretical ongoing ICD indication (TOII) at DR were defined as those with LVEF ≥40% without appropriate ICD therapy (appropriate therapy) during the first ICD service-life. A total of 107 consecutive patients were enrolled. Sixty-one patients (57%) were considered CRT responders after the index procedure. At the time of DR (56.4 ± 14.4 months from initial implant), 87% of CRT responders were free of appropriate therapy, compared with 70% of CRT nonresponders (P = 0.02). Thirty-nine patients (37%) did not meet the criteria for TOII. During follow-up (mean 26.4 ± 14.4 months after DR), 37 patients (95%) without TOII were free of appropriate therapy versus 49 of 68 patients (72%) with ongoing TOII (P = 0.007). By multivariable analysis, the only independent predictor of appropriate therapy after DR was TOII (hazard ratio = 6.43; P = 0.01). CONCLUSION: Absence of theoretical ICD indication occurs in more than one-third of CRT-D patients undergoing DR. In addition, appropriate therapy rate is relatively low (2.2% per year) in this subgroup of patients.

Prevalence of myocardial crypts in a large retrospective cohort study by cardiovascular magnetic resonance.

BACKGROUND: Myocardial crypts are discrete clefts or fissures in otherwise compacted myocardium of the left ventricle (LV). Recent reports suggest a higher prevalence of crypts in patients with hypertrophic cardiomyopathy (HCM) and also within small samples of genotype positive but phenotype negative relatives. The presence of a crypt has been suggested to be a predictor of gene carrier status. However, the prevalence and clinical significance of crypts in the general population is unclear. We aimed to determine the prevalence of myocardial crypts in a large cohort of subjects using clinical cardiovascular magnetic resonance (CMR). METHODS: Consecutive subjects referred for clinical CMR during a 12-month period (n = 1020, age 52.6 ± 17, males: 61%) were included. Crypts were defined as >50% invagination into normal myocardium and their overall prevalence, location and shape was investigated and compared between different patient groups. RESULTS: The overall prevalence of crypts was 64/1020 (6.3%). In a predefined 'normal' control group the prevalence was lower (11/306, 3.6%, p = 0.031), but were equally prevalent in ischemic heart disease (12/236, 5.1%, p = n/s) and the combined non-ischemic cardiomyopathy (NICM) groups (24/373; 6.4%, p = n/s). Within the NICM group, crypts were significantly more common in HCM (9/76, 11.7%, p = 0.04) and hypertensive CM subjects (3/11, 27%, p = 0.03). In patients referred for CMR for family screening of inherited forms of CM, crypts were significantly more prevalent (10/41, 23%, p < 0.001), including a smaller group with a first degree relative with HCM (3/9, 33%, p = 0.01). CONCLUSION: Myocardial crypts are relatively common in the normal population, and increasingly common in HCM and hypertensive cardiomyopathy. Crypts are also more frequently seen in normal phenotype subjects referred because of a family history of an inherited cardiomyopathy and HCM specifically. It is uncertain what the significance of crypts are in this group, and because of variability in the imaging protocols used and their relative frequency within the normal population, should not be used to clinically stratify these patients. Prospective studies are required to confirm the clinical significance of myocardial crypts, as their significance remains unclear.