John R. Paisey

Determination of Human Ventricular Repolarization by Noncontact Mapping Validation With Monophasic Action Potential Recordings

Background—Noncontact mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. Methods and Results—MAPs were recorded from a total of 355 beats at 46 sites in the left or right ventricle of 9 patients undergoing ablation of ventricular tachycardia guided by NCM (EnSite system). Measurements were made during sinus rhythm, constant right ventricular pacing, and ventricular extrastimuli during restitution-curve construction. The EnGuide locator signal was used to document MAP catheter locations on the endocardial geometry. UE-determined activation-recovery interval (ARI) measured at the maximum derivative of the T wave (Wyatt method) and the minimum derivative of the positive T wave (alternative method) was correlated with MAP measured at 90% repolarization (MAP90%) at the same sites. ARI correlated with MAP90% during steady state by the Wyatt method (r=0.83, P<0.001) and the alternative method (r=0.94, P<0.001). Restitution curves constructed from MAP and UE data exhibited the same characteristics, with a mean correlation coefficient of 0.95 (range, 0.90 to 0.99, P<0.001). The error between ARI and MAP90% was greater over a shorter diastolic coupling interval but was not influenced by distance of the sampling site from the multielectrode array. Conclusions—NCM accurately determines steady-state and dynamic endocardial repolarization in humans. Global, high-density, NCM data could be used to characterize abnormalities of human ventricular repolarization.

No Benefit of Complex Fractionated Atrial Electrogram Ablation in Addition to Circumferential Pulmonary Vein Ablation and Linear Ablation: Benefit of Complex Ablation Study.

Background—The optimal ablation strategy for persistent atrial fibrillation (AF) remains unclear. Methods and Results—This multicentre randomized study compared circumferential pulmonary vein ablation+linear ablation (control arm) versus circumferential pulmonary vein ablation+linear ablation+complex fractionated atrial electrogram (CFAE) ablation (CFAE arm) in patients with persistent AF. Circumferential pulmonary vein ablation was performed followed by roof and mitral isthmus ablation, before CFAE ablation in the CFAE arm. Ablation strategy was maintained at the first redo procedure. Sixty-five patients were recruited in each arm. The mean age was 61±10 years, 75% were men, median AF duration was 2 years, 42% had long-lasting persistent AF, 68% had associated cardiovascular disease, mean left atrial dimension was 46±6 mm, and median CHA2DS2-VASc score was 2. Ablation and procedure times were significantly longer in the CFAE arm (70±20 versus 55±17; 201±35 versus 152±45 minutes; P<0.005). After a mean follow-up of 35±5 months, single-procedural success off antiarrhythmic drugs at 12 months (CFAE: 30/65 [46%] versus control: 37/65 [57%]; P=0.29) and multiprocedural success (CFAE: 51/65 [78%] versus control: 52/65 [80%]; P=1.0) were not significantly different. At the first redo procedure, patients in the CFAE arm had a higher incidence of organized atrial tachycardia/flutter (24/33 [73%] versus 11/31 [35%]; P=0.005) and gap-related macro–re-entrant flutter (8/33[24%] versus 1/31[3%]; P=0.03). Early recurrence of atrial arrhythmia was an independent predictor of late recurrence. Conclusions—CFAE ablation did not confer incremental benefit when performed in addition to circumferential pulmonary vein ablation and linear ablation. It was associated with a higher incidence of gap-related flutter. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01711047.

No Benefit OF Complex Fractionated Atrial Electrogram (CFAE) Ablation in Addition to Circumferential Pulmonary Vein Ablation and Linear Ablation: BOCA Study

Background—The optimal ablation strategy for persistent atrial fibrillation (AF) remains unclear. Methods and Results—This multicentre randomized study compared circumferential pulmonary vein ablation+linear ablation (control arm) versus circumferential pulmonary vein ablation+linear ablation+complex fractionated atrial electrogram (CFAE) ablation (CFAE arm) in patients with persistent AF. Circumferential pulmonary vein ablation was performed followed by roof and mitral isthmus ablation, before CFAE ablation in the CFAE arm. Ablation strategy was maintained at the first redo procedure. Sixty-five patients were recruited in each arm. The mean age was 61±10 years, 75% were men, median AF duration was 2 years, 42% had long-lasting persistent AF, 68% had associated cardiovascular disease, mean left atrial dimension was 46±6 mm, and median CHA2DS2-VASc score was 2. Ablation and procedure times were significantly longer in the CFAE arm (70±20 versus 55±17; 201±35 versus 152±45 minutes; P<0.005). After a mean follow-up of 35±5 months, single-procedural success off antiarrhythmic drugs at 12 months (CFAE: 30/65 [46%] versus control: 37/65 [57%]; P=0.29) and multiprocedural success (CFAE: 51/65 [78%] versus control: 52/65 [80%]; P=1.0) were not significantly different. At the first redo procedure, patients in the CFAE arm had a higher incidence of organized atrial tachycardia/flutter (24/33 [73%] versus 11/31 [35%]; P=0.005) and gap-related macro–re-entrant flutter (8/33[24%] versus 1/31[3%]; P=0.03). Early recurrence of atrial arrhythmia was an independent predictor of late recurrence. Conclusions—CFAE ablation did not confer incremental benefit when performed in addition to circumferential pulmonary vein ablation and linear ablation. It was associated with a higher incidence of gap-related flutter. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01711047.

Is cardiac resynchronisation therapy feasible, safe and beneficial in the very elderly?

Objective To evaluate whether cardiac resynchronisation therapy (CRT) implantation was feasible and safe in octogenarians and the association with symptoms. Methods Consecutive patients undergoing CRT implantation were recruited from two UK centers. Patients grouped according to age: < 80 & ≥ 80 years. Baseline demographics, complications and outcomes were compared between those groups. Results A total of 439 patients were included in this study, of whom 26% were aged ≥ 80 years. Octogenarians more often received cardiac resynchronization therapy pacemaker in comparison to cardiac resynchronisation therapy-defibrillator. Upgrade from pacemaker was common in both groups (16% < 80 years vs. 22% ≥ 80 years, P = NS). Co-morbidities were similarly common in both groups (overall diabetes: 25%, atrial fibrillation: 23%, hypertension: 45%). More patient age ≥ 80 years had significant chronic kidney disease (CKD, estimated glomerular filtration rate < 45 mL/min per 1.73 m2, 44% vs. 22%, P < 0.01). Overall complication rates (any) were similar in both groups (16% vs. 17%, P = NS). Both groups demonstrated symptomatic benefit. One-year mortality rates were almost four fold greater in octogenarians as compared with the younger cohort (13.9% vs. 3.7%, P < 0.01). Conclusions CRT appears to be safe in the very elderly despite extensive co-morbidity, and in particular frequent severe CKD. Symptomatic improvement appears to be meaningful. Strategies to increase the appropriate identification of elderly patients with CHF who are potential candidates for CRT are required.

Assessment of Cardiac Arrhythmias at Extreme High Altitude Using an Implantable Cardiac Monitor: REVEAL HA Study (REVEAL High Altitude)

It has been suggested, although still unproven, that exposure at high altitude (HA) is proarrhythmic and could potentially contribute to an increased risk of sudden cardiac death.1,2 However, limited data are available to substantiate this claim, particularly at >5000 m. We hypothesized that extreme HA leads to an increased risk of pathological cardiac tachyarrhythmias, detected using an implantable cardiac monitor (ICM). Sixteen healthy adult white male British military servicemen underwent continuous ECG monitoring using a Reveal LINQ ICM (Medtronic Ltd) for ≥7 weeks before, during, and >8 weeks after an attempted summit of Mount Dhaulagiri (8167 m). They were required to have a normal 12-lead ECG and transthoracic echocardiogram at recruitment and were excluded if they had a history of cardiac arrhythmia. They underwent written informed consent, and the study was approved by the Ministry of Defense Research and Medical Ethics Committee. The participants flew from the United Kingdom to Kathmandu, Nepal (1400 m, days 1–2), then by road (days 3–4) to 2679 m. Thereafter, they trekked carrying moderate loads to 3720 m (day …

Examination of a Middle Cardiac Vein Defibrillation Coil as Stand‐Alone Anode, Auxiliary Anode, and Bystander Electrode in a Transvenous Defibrillation Circuit

In porcine studies anodes in the middle cardiac vein compare favorably with those in the RV. It has not been demonstrated whether the RV and middle cardiac vein or the middle cardiac vein alone anodes are superior when shocking to a conventional SVC and active housing cathode nor whether a bystander middle cardiac vein electrode exerts a passive electrode affect. Twelve pigs were anesthetized and had an active housing implanted in the left pectoral region and defibrillation coils placed at the RV apex and in the SVC. A custom‐made defibrillation coil (Ela Medical) was advanced into the middle cardiac vein through a 9 Fr transvenous catheter. The DFT for three anodes (RV; RV and middle cardiac vein; middle cardiac vein) to the SVC and active housing was then assessed by a three reversal binary search, the order of testing was randomized. In seven animals DFT was assessed in the same way for the configuration of RV to SVC and active housing twice more, with and without a bystander middle cardiac vein coil electrode in place. The results were middle cardiac vein 7.5 ± 1.7 J, RV and middle cardiac vein 7.3 ± 1.7 J reduced DFT significantly compared to RV 13.8 ± 4.2 J (both P < 0.000). There was no significant difference between the middle cardiac vein and the middle cardiac vein and RV (P = 0.67, 95% CI for difference − 0.64–0.96). The DFT of RV to SVC and the active housing was the same with (13.2 ± 4.0) and without (13.7 ± 4.2) the middle cardiac vein bystander coil in place (P = 0.177, 95% CI for difference − 0.33–1.33 J). Shocking to a SVC and active housing cathode, middle cardiac vein, and RV and middle cardiac vein anodes are equally effective in lowering DFT compared to the RV. The middle cardiac vein coil electrode does not exert a passive electrode affect on the RV to the SVC and active housing defibrillation.

Radiation Peak Skin Dose to Risk Stratify Electrophysiological Procedures for Deterministic Skin Damage

Ionising radiation is has the potential to cause harm both by increasing the probability future malignancy (stochastic mechanisms) and by direct physical injury (deterministic mechanisms). Several measures have been developed to quantify radiation exposure during a procedure and cardiologists usually refer to fluoroscopic screening time (FST). FST, however, has limitations for predicting deterministic injury which is directly dependant on peak skin dose (PSD). We compared FST to PSD for a range of interventional cardiac electrophysiology procedures. Methods: All patients undergoing electrophysiology procedures during a 2-month period in our institution were studied. Demographic details, nature of procedure, FST and PSD were measured. The FST to PSD ratio was calculated and compared between patient and procedural factors. Results: 67 procedures on patients (23 female) with body mass index (BMI) of 28 (SD 5)Kg/m2 were studied. Screening times ranged from 0.2 to 96.6 min (median 11.2). PSD ranged from <0.1 to 1108 mGy (median 141). There was a positive correlation between PSD to FST ratio and BMI (r= 0.59, p < 0.001). The PSD to FST ratio was higher in cardiac resynchronization therapy (CRT) devices than single or dual chamber ICDs (p= 0.002). Conclusion: FST is not a reliable predictor of deterministic skin injury and in high-risk procedures such as CRT devices and those on individuals of high BMI PSD should be measured.

Non contact mapping of human cardiac restitution is accurate and reproducible

15th World Congress in Cardiac Electrophysiology and Cardiac Techniques: Cardiostim 2006, Nice–French Riviera, France, 14-17 June 2006. In Europace, 2006, v. 8 Supplement 1, p. 43/5