Circulation: Arrhythmia and Electrophysiology November 2018 issue

Circulation: Arrhythmia and Electrophysiology On the Beat

Dr Paul Wang: Welcome to the monthly podcast On the Beat, for Circulation: Arrhythmia, and Electrophysiology. I'm Dr Paul Wang, editor-in-chief, with some of the key highlights from this month's issue.

In our first paper, Elizabeth Saarel and associates describe the analysis of athletes in the ICD sports registry. The authors found that over a median follow-up of 42 months of 129 young athletes, and a mean age of 16 years, there were 35 athletes, or 27%, that received a total of 38 shocks. Long QT syndrome and hypertrophic cardiomyopathy were the most common diagnoses. While shocks related to competition and practice were not uncommon, there were no serious adverse sequelae. Lead malfunction rates were similar to previously reported in an unselected pediatric ICD populations. There were no occurrences of death, arrest, injury related to arrhythmia during sports. There was one ventricular tachycardia ventricular fibrillation storm during competition.

In our next paper, Kedar K. Aras and associates theorize that the tissue volume to wavelength volume ratio is important in determining ventricular fibrillation sustainability. They perform panoramic optical mapping of coronary perfused human left ventricular wedge preparations, which were subjected to acts of potential duration changes produced by IK,ATP agonist pinacidil and antagonist glybenclamide. They found that pinacidil and escalating concentrations progressively decreased the volume wavelength in ventricular fibrillation became sustained when the tissue volume to wavelength ratio was above the safety factor, K equals 4.4. In addition, ventricular fibrillation was only sustained when the ventricular volume exceeded the critical wavelength volume defined by the product of pacing cycle wave length in the longitudinal transverse and transmural directions.

In our next paper Thomas Deneke and associates examine the ability of a novel infrared thermal probe to predict endoscopically detected thermal esophageal lesions post atrial fibrillation ablation. They studied six patients undergoing their first pulmonary vein isolation, using radio frequency point by point catheter ablation in the HEAT-AF study; 12 or 19% of patients had endoscopically detected thermal esophageal lesions. The peak esophageal temperature Tpeak was significantly higher, 56.3 degrees Celsius versus 45.7 degrees Celsius. P less than 0.0001 in patients with endoscopically detected thermal esophageal lesions compared to those without lesions. Logistical regression analysis demonstrated Tpeak was a statistically significant predictor, P equals 0.0008 pf endoscopically detected thermal esophageal lesions with an odds ratio of 1.52.

In our next paper Dian Cheng and associates examine a novel algorithm incorporating right precordial and posterior leads to discriminate between left ventricular outflow tract and right ventricular outflow tract foci. The V3R to V7 index was prospectively tested in consecutive patients at four centers. In 94 patients of the validation cohort with 79% RVOT foci, a QS pattern in lead V3R exclusively recorded in right ventricular outflow tract foci, while an S wave in V3 was exclusively recorded in left ventricular outflow tract foci. The V3R to V7 index of LVOT origin was significantly great than that of RVOT 1.05 versus 0.28 P, less than 0.001 with a V3R to V7 index of greater than equal to 0.85 predicting an LVOT origin with 87% sensitivity and 96% specificity. With the V3R to V7 index of 0.85 or greater RVOT origin could be excluded with 98.6% accuracy.

In the next paper Jim Cheung and associates examine the in-hospital outcomes, cause, and thirty-day readmissions following catheter ablation of MI associated ventricular tachycardia. The authors use a nationwide readmissions database to evaluate 4109 admissions for catheter ablation of MI associated ventricular tachycardia occurring between 2010 and 2015. The index admission in-hospital mortality rate was 2.7% and the procedural complication rate after ventricular tachycardiablation was 11.5%. Pulmonary hypertension, lung disease, obesity and coagulopathy were independent predictors of mortality. Following discharge after VT ablation the thirty-day readmission rate was 19.2%. With the median time to readmission of 10.0 days, in an in-hospital mortality of 2.9%. Cardiac causes accounted for 74% of readmissions. With ventricular tachycardia accounting for 41% of admissions and congestive heart failure accounting for 14% of readmissions. Pulmonary hypertension, congestive heart failure, smoking, chronic pulmonary disease, and prolonged index hospitalization were significant independent predictors of thirty-day readmission. After adjustment thirty-day readmissions were associated with a 38.9% increase in cumulative hospitalization costs.

In the next paper Tomofumi Nakamura and associates examine the relation of hemorrhagic and thromboembolic events with anticoagulations strategy in the setting of epicardial axis procedures for ventricular arrhythmia mapping and ablation. In 355 patients oral anticoagulants were stopped perioperatively in heparin administered prior to the procedure. The patients were divided to three groups per the anticoagulations strategy. Group 1, no heparin was administered before pericardial access, Group 2, heparin was administered in reverse before pericardial access, and Group 3 heparin was administered and not reversed. Significant pericardial bleeding defined is greater than 80 milliliter occurred in 46 cases or 13% and did not differ among the three groups. Unintentional cardiac puncture in left ventricular chest infraction less than [inaudible 00:07:32] 35% were independently associated with pericardial bleeding with an odd ratio of 16.4 or 2.28. Of 38 procedures with unintentional cardiac puncture there were no differences in pericardial bleeding for different anti-coagulant strategies. Thromboembolic events occur in 5 patients, 1 coronary embolism, 1 stroke, 2 deep vein thrombosis, and 1 fatal pulmonary embolism and 1 thrombus on a temporary ventricular assist device.

In the next paper, Elisabeth Mouws and associates examine whether the combination of lines of conduction block with multiple wave fronts at the pulmonary vein area may result in increased arrhythmogenicity and susceptibility to atrial fibrillation. The author performed intra-operative high-density epicardial mapping of pulmonary vein area and is 450 sites with an intra-electrical distance of 2 milliliters which performed during sinus rhythm in 327 patients. With and without preoperative intra-fibrillation. Excitation of the pulmonary vein area occurred via multiple consecutive wave fronts in the vast majority, 81% of patients. In total 561 wave fronts were observed which propagated through the septal or paraseptal regions tore the pulmonary vein area in 82%. Substantial dissociation of consecutive wave fronts was observed with delta activation times of 10.6 milliseconds. No difference was observed in delta activation times of consecutive wave fronts during sinus rhythm between patients with and without atrial fibrillation. In excitation-based risk factor model including conduction delay of greater equal to 6 millimeters conduction block of greater than or equal to 6 millimeters and conduction delay conduction block of 16 millimeters or greater, wave fronts vie the posterior inferior and posterior superior in multiple opposing wave fronts demonstrated a 5-fold risk of atrial fibrillation when multiple risk factors were present.

In our final paper Yoshitaka Kimura and associates examine the prognostics significance of PR interval prolongation on adverse cardiac events. They studied 176 patients with repaired tetralogy of flow with a median age of 17.4 years then they evaluated their correlation with right ventricular volume and function measured by cardiac magnetic resonance and the significance as a risk factor of adverse cardiac events were ventricular arrhythmias, atrial arrhythmias, heart failure, hospitalization, complete AV block, and all cause death. First degree AV block was noted 25 patients or 14% during a median follow-up of 10 years there was a progressive prolongation of PR interval 2.0 milliseconds per year. Importantly there were significant correlations between PR interval prolongation and right ventricular enlargement or right ventricular disfunction. In contrast, patients who underwent pulmonary valve replacement, N equal 23, significant shortening of PR interval was noted, 204 versus 176 milliseconds, P equals 0.007. Cox regression analysis showed that the first degree AV block was an independent risk factor for ventricular arrhythmias hazard ratio 5.479, in complete heart block, hazard ratio 27.67, and it had a tendency for heart failure hospitalization, hazard ratio 3.3. In addition PR interval prolongation greater than 2 millisecond per year was also a significant risk factor for ventricular arrhythmias regardless of the presence or absence of first degree AV block in enrollment.

That's it for this month. We hope that you will find the journal to be the go to place for everyone interested in the field. See you next time.