Usama Boles

Interatrial block and interatrial septal thickness in patients with paroxysmal atrial fibrillation undergoing catheter ablation: Long-term follow-up study

Interatrial block (IAB) is a strong predictor of recurrence of atrial fibrillation (AF). IAB is a conduction delay through the Bachman region, which is located in the upper region of the interatrial space. During IAB, the impulse travels from the right atrium to the interatrial septum (IAS) and coronary sinus to finally reach the left atrium in a caudocranial direction. No relation between the presence of IAB and IAS thickness has been established yet.

Loss of atrial pacing in a patient with a dual-chamber permanent pacemaker: What is the mechanism?

1. Atrial oversensing due to lead integrity failure (fracture, insulation failure) or connector problems between the header and the lead. 2. Atrial lead displacement: no evidence of microor macrodisplacement was found on chest radiography. 3. Asynchronous mode of pacing (VOO) due to magnet or programming: device interrogation ruled out this differential diagnosis. The device was fully functional in DDDR mode.

Coronary Sinus Electrograms May Predict New-onset Atrial Fibrillation After Typical Atrial Flutter Radiofrequency Ablation (CSE-AF)

Background Complex fractionated electrograms (EGMs) of the coronary sinus electrograms (CSEs) are employed as a target during radiofrequency ablations (RFA) of atrial fibrillation (AF). Anatomically, CSEs includes both of left atrium (LA), coronary sinus musculature and right atrium (RA) electrograms. Aim To determine the significance of fractionated CSE and delayed potentials as a predictor of new-onset AF after radiofrequency ablation (RFA) of isolated atrial flutter (AFL). Methods Consecutive patients underwent AFL ablation. Fractionated and/or continuous discrete activities were recorded from coronary sinus electrograms during sinus rhythm and during pacing. Earliest CSE to the S nadir or peak R in milliseconds was recorded and considered as propagation delay for EGMs. Results Forty patients were included during a mean follow-up period of 55.1± 15.8 months. Twenty patients (50 %) developed AF while the remaining 20 patients maintained sinus rhythm(SR) during the follow-up period. Proximal and mid CSEs were significantly fractionated in AF group compared to group with no AF development (65 % and 60% Vs. 35 % and 30 %, p = 0.03, respectively). However, during pacing from distal duo-decapolar catheter (pole 1-2), distal CSEs alone were significantly fractionated (p < 0.05) compared to SR group. Significant delayed propagation of proximal CSE during pacing and in sinus rhythm were observed in AF group (12.3 ± 9.2 ms vs 7.1 ± 3.6 ms, p = 0.03) and (7.2 ± 2.9 ms Vs 8.1 ± 4.6 ms, p= 0.02) in the same order. Conclusion Incidence of AF is associated with fractionated proximal and mid CSE in sinus rhythm and distal CSE during paced rhythm after isolated AFL ablation. Delayed proximal CSE propagation is correlated with AF incidence.

Gold-tip versus contact-sensing catheter for cavotricuspid isthmus ablation: A comparative study

OBJECTIVE Radiofrequency (RF) ablation is a highly successful procedure for the management of typical atrial flutter (AFL), an abnormal heart rhythm originating within the atria. There is no strong evidence that the use of contact force (CF) has any impact on procedural duration or acute success in the management of cavotricuspid isthmus (CTI)-dependent AFL. The aim of this study was to compare acute procedural parameters using a non-CF, 4-mm, gold-tip, irrigated catheter and a CF-sensing catheter in patients with AFL. METHODS This was a retrospective cohort study. Consecutive patients who underwent typical AFL catheter ablation with either a gold-tip or CF-sensing catheter were enrolled. The procedural parameters obtained were: time to achieve bidirectional block, time to terminate AFL, total duration of RF application, procedure duration, fluoroscopy time, acute reconnection within 20 minutes following the last RF application, and procedural complications. RESULTS Of the 40 patients screened, 37 were included in the study. The procedural endpoint of bidirectional isthmus block was achieved in all patients. The use of gold-tip catheters was associated with a shorter length of time to achieve bidirectional block (median time: 20.0 minutes [interquartile range {IQR}: 12.0-28.0 minutes]) compared with a median time of 36.0 minutes (IQR: 12.0-53.0 minutes; p=0.048) in the CF group. Furthermore, there was a trend toward reduced procedural duration in favor of the gold-tip catheter (median goldtip: 74.0 minutes [IQR: 57.0-84.0 minutes]; median CF: 85.0 minutes [IQR: 57.0-107.0 minutes]; p=0.171). A greater requirement for the use of long sheaths was observed in cases where the CF catheter was employed for the procedure (CF: 11, 57.9 %; non-CF: 1, 5.6%; p=0.005). CONCLUSION The time required to achieve bidirectional block, which is also reflected in the procedural time, was less when using a gold-tip catheter, and there was less need for the use of a long sheath. Further studies may be useful to evaluate this finding.

“Spontaneous Twiddler's” Syndrome: The Importance of the Device Shape: “SPONTANEOUS TWIDDLER'S” SYNDROME

Twiddlers syndrome is caused by patient manipulation of the cardiac implantable device (CID) around its central axis within the pocket, resulting in retraction and dislocation of the electrodes. There are, however, some reports that Twiddlers syndrome may occur spontaneously without the patients manipulation. This remains contentious as it may be argued that patients may not want to admit to manipulating the CID or may have been unaware of their actions. Recently, we have observed three very similar cases with a “spontaneous” Twiddlers syndrome resulting in lead displacement. All of the three patients denied device manipulation and were not prone to somnambulism or repetitive involuntary motor behaviors. It, therefore, seems highly unlikely that all patients could have manipulated the device in exactly the same way to result in the same postrotational position within the implant pocket. The fact is that the same device was implicated in all these cases in a relatively similar time sequence from implant to recognition of the implantable cardiac defibrillator rotation. We postulate that the unique elongated decision of the Fortify Assura (St. Jude Medical, Minneapolis, MN, USA) ICD makes this device prone to spontaneous rotation as is exemplified by our case series.

Left Atrial Appendage characteristics in patients with Persistent Atrial Fibrillation undergoing catheter ablation (LAAPAF Study)

Background Despite technological and scientific efforts, the recurrence rate of persistent atrial fibrillation (AF) remains high. Several studies have shown that in addition to pulmonary vein (PV) isolation other non-PV triggers, particularly left atrial appendage may be the source of initiation and maintenance of AF. There are few studies showing the role of left atrial appendage (LAA) isolation in order to obtain higher success rate in persistent AF patients. Objective We analyzed the LAA volume, volume index and shape relative to the LA in patients with persistent AF undergoing AF ablation. Methods Fifty-nine consecutive patients with persistent AF who underwent catheter ablation were enrolled. Computerized tomography (CT) was performed in order to assess left atrial and PV anatomy including the LAA. Digital subtraction software (GE Advantage Workstation 4.3) was used to separate the LAA from the LA and calculate: LA volume (LAV), LA volume index (LAV/body surface area), LAA volume (LAAV), LAA volume index (LAA volume/LA volume), and LAA morphology [chicken wing (CW) or non-chicken wing (NCW)]. Results The mean age was 64.6 ± 9.8 years, 44 % male, and LA diameter 47.6 ± 7.8 mm. Median follow-up (FU) was 13 months. All patients had antral isolation of PVs and ablation of complex fractionation ± linear ablation (roof line/superior coronary sinus/mitral line). Among 59 patients with persistent AF, 26 (44 %) patients were diagnosed with AF recurrences. Mean LAV was 145.0 ± 45.9 ml, LAVI 68.9 ± 20.0 ml/m2, LAAV 10.3 ± 4.0 ml, and LAAVI 7.3 ± 2.7 ml/m2. LAA shape was non-chicken wing (NCW) in the majority of patients (51 %). LAA parameters were not significantly different between patients with and without AF recurrence (LAAV 11.0 ± 4.3 ml vs. 9.7 ± 3.8 ml, p=0.26; LAAVI 7.5 ± 3.0 ml/m2 vs. 7.2 ± 2.5 ml/m2, p=0.71; LAA shape of NCW 50 % vs 52 %, p=0.75, respectively). LAV was significantly correlated with the LAAV (r: o.47, p=0.009). The incidence of NCW LAA was significantly higher in patients with previous stroke/TIA (80 % vs. 20 %, p=0.04). Conclusion The LAA anatomical characteristics (volume/volume index and the shape) were comparable in patients with/out AF recurrence post PVI. It remains to be determined if additional LAA isolation will impact outcomes in patients with persistent AF.

High Voltage Guided Pulmonary Vein Isolation in Paroxysmal Atrial Fibrillation

Background Ablation of the pulmonary vein (PV) antrum using an electroanatomic mapping system is standard of care for point-by-point pulmonary vein isolation (PVI). Focused ablation at critical areas is more likely to achieve intra-procedural PV isolation and decrease the likelihood for reconnection and recurrence of atrial fibrillation (AF). Therefore this prospective pilot study is to investigate the short-term outcome of a voltage-guided circumferential PV ablation (CPVA) strategy. Methods We recruited patients with a history of paroxysmal atrial fibrillation (AF). The EnSite NavX system (St. Jude Medical, St Paul, Minnesota, USA) was employed to construct a three-dimensional geometry of the left atrium (LA) and voltage map. CPVA was performed; with radiofrequency (RF) targeting sites of highest voltage first in a sequential clockwise fashion then followed by complete the gaps in circumferential ablation. Acute and short-term outcomes were compared to a control group undergoing conventional standard CPVA using the same 3D system. Follow-up was scheduled at 3, 6 and 12 months. Results Thirty-four paroxysmal AF patients with a mean age of 40 years were included. Fourteen patients (8 male) underwent voltage mapping and 20 patients underwent empirical, non-voltage guided standard CPVA. A mean of 54 ± 12 points per PV antrum were recorded. Mean voltage for right and left PVs antra were 1.7±0.1 mV and 1.9±0.2 mV, respectively. There was a trend towards reduced radiofrequency time (40.9±17.4 vs. 48.1±15.5 mins; p=0.22). Conclusion Voltage-guided CPVA is a promising strategy in targeting critical points for PV isolation with a lower trend of AF recurrence compared with a standard CPVA in short-term period. Extended studies to confirm these findings are warranted.

Standardized programming to reduce the burden of inappropriate therapies in implantable cardioverter defibrillators - Single centre follow up results

Background Current algorithms and device morphology templates have been proposed in current Implantable Cardioverter-Defibrillators (ICDs) to minimize inappropriate therapies (ITS), but this has not been completely successful. Aim Assess the impact of a deliberate strategy of using an atrial lead implant with standardized parameters; based on all current ICD discriminators and technologies, on the burden of ITS. Method A retrospective single-centre analysis of 250 patients with either dual chamber (DR) ICDs or biventricular ICDs (CRTDs) over a (41.9 ± 27.3) month period was performed. The incidence of ITS on all ICD and CRTD patients was chronicled after the implementation of standardized programming. Results 39 events of anti-tachycardial pacing (ATP) and/or shocks were identified in 20 patients (8% incidence rate among patients). The total number of individual therapies was 120, of which 34% were inappropriate ATP, and 36% were inappropriate shocks. 11 patients of the 250 patients received ITS (4.4%). Of the 20 patients, four had ICDs for primary prevention and 16 for a secondary prevention. All the episodes in the primary indication group were inappropriate, while seven patients (43%) of the secondary indication group experienced inappropriate therapies. Conclusions The burden of ITS in the population of patients receiving ICDs was 4.4% in the presence of atrial leads. The proposed rationalized programming criteria seems an effective strategy to minimize the burden of inappropriate therapies and will require further validation.

Clinical evaluation of R860Q semi-conservative amino acid substitution in CACNA1C gene in association with long QT syndrome

Article history: Received 26 November 2016 Accepted 31 March 2017 Available online 10 April 2017 she underwent insertion of an implantable cardioverter defibrillator for secondary prevention purpose. A genetic testing panel including sequencing and deletion/duplication analysis of 12 genes associated with LQTS was performed which revealed two variants of unknown significance – one in the CACNA1C gene and the other in the KCNE1 gene. We obtained a targeted 4-generation pedigree (Fig. 1), which revealed

Unipolar voltage threshold of 5.0 mV is optimal to localize critical isthmuses in post-infarction patients presenting with ventricular tachycardia

INTRODUCTION Bipolar voltage mapping is useful to delineate post-infarct endocardial scar and guide ablation of ischemic VT. The role of unipolar mapping is not yet well defined. The aim of this study was to assess the correlation between electrophysiological findings in patients with ischemic VT and unipolar voltage maps using different cut-offs. METHODS We included 10 patients (age 67 ± 7 years, ejection fraction 33 ± 10%) with ischemic cardiomyopathy undergoing catheter ablation for recurrent VT. Patients with right-sided VTs were excluded. In all patients a unipolar voltage map was constructed during right ventricular pacing. Ablation was performed guided by activation and entrainment mapping in hemodynamically stable VTs and by pace-mapping and abnormal (late/split/fractionated) potentials in unstable VTs. Subsequently, the unipolar voltage maps were analyzed off-line using cutoffs from 1.0 to 8.0 mV and correlated with the isthmus sites. RESULTS A total of 17 sustained VTs were induced in the 10 patients and non-inducibility of the clinical VT was achieved in 90% of patients by endocardial ablation. The optimal cutoff was 5.0 mV. By using this value, the mean surface area of abnormal unipolar voltage was 43.8% and 95% of all VT isthmuses were located within the area of scar, as well as 81% of abnormal potentials. In addition, 71% of isthmuses were at less than 1cm from the scar border. CONCLUSION Unipolar voltage mapping showed good correlation with areas of isthmuses and abnormal electrograms in patients with scar-related VT, with a cut-off of 5.0 mV allowing the best delineation of ablation targets.