Termination of macroreentrant atrial arrhythmias by pacing stimuli without global propagation.

BACKGROUND: Electrical stimulation during ventricular tachycardia resulting in tachycardia termination without global propagation (TWGP) is a well-recognized phenomenon. However, there is a paucity of literature showing a similar phenomenon in atrial arrhythmias. OBJECTIVE: The purpose of the study was to evaluate the significance of TWGP in atrial arrhythmias. METHODS: Electrophysiological studies performed from 2000 to 2019 at Methodist Hospital, Indiana University were reviewed retrospectively. Thirty-four patients were identified in whom stimulation during atrial tachycardia/flutter resulted in TWGP. RESULTS: Of the 34 patients, 12 (29%) had cavotricuspid isthmus (CTI)-dependent atrial flutter and 22 (71%) had other atrial arrhythmias during which TWGP was seen. Mean age of the population was 53 ± 13 years; and 68% were male. Previous catheter ablation for atrial fibrillation, atrial flutter, or other atrial tachyarrhythmias had been performed in 70.5%, and 44% previously had undergone cardiac surgery involving the atria. Congenital heart disease was present in 20.5%; 3 patients were status post lung transplant. Mean cycle length of atrial arrhythmia in which TWGP was seen was 317 ± 76 ms. The sites at which TWGP was seen reproducibly were highly specific for successful termination of the arrhythmias with radiofrequency energy. The arrhythmia circuits were 12 CTI-dependent atrial flutter, 11 left atrial macroreentrant atrial tachycardia (MRAT), 1 involving both left and right atria, and 8 were other right atrial MRAT. CONCLUSION: Termination of macroreentrant atrial arrhythmias by pacing stimuli without global propagation identifies a narrow diastolic isthmus at which catheter ablation is highly effective.

Newer diagnostic criteria for identification of epicardial origin of ventricular tachycardia/premature ventricular complex.

Aim: The study defines criteria for localization of ventricular arrhythmias. Materials & methods: Data from 40 premature ventricular complex (PVC)/ventricular tachycardia (VT) were studied. The interval from PVC QRS onset to His potential and ratio of this interval to PVC/VT QRS duration was analyzed. Patients were divided into epicardial and endocardial groups based on mapping/successful ablation site. Results: The interval from PVC QRS onset to His potential in the epicardial versus endocardial group was 99 ± 21 ms and 64 ± 37 ms (p = 0.002). A cut off of 88 ms had a sensitivity of 73% and specificity of 76%. A cut off of 0.50 for the ratio had a sensitivity of 82% and specificity of 72%. Conclusion: Two new parameters can help localization of PVC/VTs origin.

Mechanical suppression of premature ventricular complexes during catheter ablation procedures.

INTRODUCTION: Mechanical suppression of premature ventricular complexes (PVCs) is not a well-known observation. We retrospectively reviewed this phenomenon in the Ventricular Arrhythmia (VA) ablation procedures performed at Richard L. Roudebush Veterans Health Administration (VHA) center. METHODS: Data from 40 consecutive patients who underwent VA ablation at VHA, Indianapolis, IN, with 44 VA was included in the study. Demographic and electrophysiological parameter data was collected. RESULTS: Overall the mean age of the population was 64 ± 11 years. The phenomenon of mechanical suppression was seen in 11 PVCs. The mean age was 59 ± 15 years in the group in which mechanical suppression was seen. Of the 11 cases, the site of earliest activation was seen in the coronary sinus in 8 and in the pulmonary artery in 3. In one case catheter ablation was not performed because of proximity to the left coronary artery system. However, sustained pressure at the site with earliest electrograms (-35 ms) and 95% pacematch resulted in long-term suppression of PVCs. In the cases in which mechanical suppression was seen, there was a statistically significant reduction in PVC burden compared to pre ablation PVC load (1.1% ± 1.50% (post ablation) versus 24.04% ± 13.07% (pre ablation) versus p < 0.05). In all the 11 cases the site of mechanical suppression was also the site with earliest electrograms. CONCLUSION: This case series illustrates phenomenon of mechanical suppression of PVCs as an indication for good site for successful ablation in unique veteran patient population.

Novel electrocardiographic criteria for diagnosis of premature ventricular complexes arising from the base of left ventricle.

PURPOSE: We report new electrocardiographic criteria (ECG) for localizing premature ventricular complexes (PVCs) originating from the base of the left ventricle (LV). METHODS: QRS deflection (positive negative or negative positive) in lead aVR and aVL respectively, were evaluated in 41 PVC/VT cases. RESULTS: There were a total of 41 patients, age 64 ± 11 years. Twelve patients had QRS deflection in aVR which were completely opposite to the deflection in aVL. If the PVC originated from basal septum, aVR was negative while aVL positive and vice versa when it was from the baso-lateral LV. PVCs from other LV sites had aVR and aVL deflection in the same direction. The ECG criteria had a sensitivity and specificity of 91% and 84%, respectively. CONCLUSION: We propose a new ECG criterion to localize PVCs originating from the base of the LV.

Unique features of epicardial ventricular arrhythmias/premature ventricular complexes ablated from coronary venous system in veteran population.

INTRODUCTION: Ventricular arrhythmias/premature ventricular complexes (VA/PVCs) that can be ablated from within the coronary venous system (CVS) have not been described in the United States Veterans Health Administration (VHA) population. We retrospectively studied the VA/PVCs ablations that were performed in the VHA population. METHODS: Data from 42 consecutive patients who underwent VA/PVCs ablation at Veterans Affairs Hospital, Indianapolis, IN, with 44 VA/PVCs was included in the study. Patients were divided into two groups (CVS group [n = 10], and non-CVS group [n = 32]) based on where the earliest pre-systolic activation was seen with >95% pacematch. RESULTS: The mean age in CVS group was 65 ± 8 years versus 64 ± 12 years (p = 0.69) in non-CVS group. Overall there was a statistically significant reduction in PVC burden post ablation (27.7% (pre-ablation) versus 4.7% (post-ablation). In the 10 patients in the CVS group, either ablation or catheter-related mechanical trauma resulted in complete (n = 6 [60%]) or partial (n = 4 [40%]) long-term suppression of VA/PVCs. Right bundle branch block-type VA/PVC (9/11: 82%) was the most common morphology in the CVS group, whereas in the non-CVS group, this type was seen in only 3/33 (9%). The CVS group (25% of total VA/PVCs) had shorter activation time compared to non CVS group. CONCLUSION: In our experience VA/PVCs with electrocardiograms suggestive of epicardial origin can often be safely and successfully ablated within the coronary venous system. These arrhythmias have unique features in Veterans patient population.

Natural History of Implantable Cardioverter-Defibrillator Implanted at or after the Age of 70 years in a Veteran Population: A Single Center Study.

BACKGROUND: The median age of patients in major Implantable Cardioverter-defibrillator (ICD)trials (MUSTT, MADIT-I, MADIT-II, and SCD-HeFT) was 63-67 years; with only 11% ≥70 years. There is little follow-up data on patients over 70 years of age who received an ICD for primary/secondary prevention of sudden cardiac death, particularly for veterans. OBJECTIVE: The aim of this study was to study the natural history of ICD implantation for veterans over 70 years of age. METHODS: We retrospectively reviewed single center ICD data in 216 patients with a mean age at implantation 76 ± 4 years. The ICD indication was primary prevention in 161 patients and secondary prevention in 55 patients. The ICD indication was unavailable in 4 patients. RESULTS: Mean duration of follow up was 1686 ± 1244 days during which 114 (52%) patients died. Of these, 31% died without receiving any appropriate ICD therapy. Overall, 60/216 (28%) received appropriate therapy and 28/216 (13%) received inappropriate therapy. Patients who had ICD implantation for secondary prophylaxis had statistically more (p= 0.02) appropriate therapies compared to patients who had ICD implantation for primary prevention. Indication for implantation and hypertension predicted appropriate therapy, while age at the time of implantation and presence of atrial fibrillation predicted inappropriate therapies. Overall, 7.7% had device related complications. CONCLUSIONS: Although 28% septuagenarians in this study received appropriate ICD therapy, they had high rates of mortality, inappropriate therapy, and device complications. ICD implantation in the elderly merits individualized consideration, with higher benefit for secondary prevention.