Risk factors and outcomes of sudden cardiac arrest in pediatric heart transplant recipients.

BACKGROUND: Sudden cardiac arrest (SCA) is a prevailing cause of mortality after pediatric heart transplant (HT) but remains understudied. We analyzed the incidence, outcomes, and risk factors for SCA at our center. METHODS: Retrospective review of all pediatric HT patients at our center from January 1, 2009 to January 1, 2021. SCA was defined as an abrupt loss of cardiac function requiring cardiopulmonary resuscitation and/or mechanical circulatory support (MCS). Events that occurred in the setting of limited resuscitative wishes, or while on MCS were excluded. Patient characteristics and risk factors were analyzed. RESULTS: Fourteen of 254 (6%) experienced SCA at a median of 3 (1, 4) years post-HT. Seven (50%) events occurred out-of-hospital. Eleven (79%) died from their initial event, 2 (18%) after failure to separate from extracorporeal membrane (ECMO). In univariate analysis, black race, younger donor age, prior acute cellular rejection (ACR) episode, pacemaker and/or ICD in place, and pre-mortem diagnosis of allograft vasculopathy were associated with SCA (P = .003-0.02). In multivariable analysis, history of ACR, younger donor age, and black race retained significance. [OR = 6.3, 95% CI: 1.6-25.4, P = .01], [OR = 0.9, 95% CI: 0.8-1, P = .04], and [OR = 7.3, 95% CI: 1.1-49.9, P = .04], respectively. SCA occurred in 3 patients with a functioning ICD or pacemaker, which failed to restore a perfusing rhythm. CONCLUSIONS: SCA occurs relatively early after pediatric HT and is usually fatal. Half of events happen at home. Those who received younger donors, have a history of ACR, or are of black race are at increased risk. ICDs/pacemakers may offer limited protection.

Ventricular arrhythmias following transcatheter pulmonary valve replacement with the harmony TPV25 device.

BACKGROUND: Transcatheter pulmonary valve replacement (TPVR) with the Harmony valve (Medtronic, Inc.) was recently approved to treat postoperative native outflow tract pulmonary regurgitation. While the 22 mm Harmony valve Early Feasibility Study demonstrated ventricular tachycardia (VT) in only 5% of patients, little is known about ventricular arrhythmias after TPVR with the larger 25 mm valve (TPV25). METHODS: A single center review was performed of patients with TPV25 implant from 2020 to 2021. Demographic, cardiac, procedural, and postimplant cardiac telemetry data were collected and compared between patients who did and did not have peri-implant ventricular arrhythmia. RESULTS: Thirty patients underwent TPV25 at a median age of 30 years. On postimplant telemetry, VT events were documented in 12 patients (40%); 11 nonsustained VT (NSVT) (median 3 episodes per patient and 6 beats per episode, maximum 157 episodes) and 1 sustained VT (3%), with Torsades de Pointes secondary to a short coupled premature ventricular contraction (PVC). VT events were associated with annular valve positioning (p < 0.001) and increased postimplant PVC burden (p < 0.0001), but there was no association between VT and other demongraphic, historical, or procedural factors. The frequency of NSVT events fell from 3/h from 0 to 12 h postimplant to 0.5/hr from 12 to 24 h (p < 0.001). CONCLUSION: VT occurred commonly (40%) in the first 24 h after TPV25 implant, with self-limited NSVT in 11 of 12 patients and 1 patient with cardiac arrest secondary to Torsades de Pointes. VT only occurred with annular valve positioning. Larger, longer-term studies are needed to determine risk factors for and natural history of post-TPVR VT.

Infants born with critical CHD in Arizona and capacities of birth centres for screening and management.

OBJECTIVES: The aims of this study were to identify locations of births in Arizona with critical CHD, as well as to assess the current use of pulse-oximetry screening and capacities of birth centres to manage a positive screen. Study design Infants (n=487) with a potentially critical CHD were identified from the Arizona Department of Health Services from 2012 and 2013; charts were retrospectively reviewed. Diagnosis was confirmed using echocardiographies. ArcGIS was used to generate maps to visualise the location of treating facility and mother's residence. Birth centres were surveyed to assess screening practices and capacities to manage critical CHD in 2015. RESULTS: Of the 272 patients identified with critical CHD, 52% had been diagnosed prenatally. Patients travelled an average distance of 55.1 miles to their treating facility. Mortality was not related to prenatal diagnosis (p=0.30), living at a high elevation (p=0.82), or to distance travelled to the treating facility (p=0.68). Of 50 birth centres, 33 responded to the survey and all centres practiced critical CHD screening. A total of 25 centres could perform paediatric echocardiographies; 64% of these centres could digitally transmit echocardiograms. In all, 24 birth centres maintained access to prostaglandins. CONCLUSIONS: Pulse-oximetry screening in newborns is currently implemented in the majority of Arizona hospitals. Although most centres could perform initial management steps following a positive screen, access to paediatric cardiology services was limited. Patients with critical CHD sometimes travelled a great distance to treating facilities. Digital transmission of echocardiograms or tele-echocardiography would reduce the distance travelled for the management of a positive screen, decrease the financial burden of transportation, and expedite care for critically ill neonates.

Current Device Needs for Patients with Pediatric and Congenital Heart Disease.

Pediatric electrophysiologists believe that there is a paucity of pediatric-specific cardiac implantable electronic devices (CIEDs) available for their patients. Specific patient characteristics such as vascular size, intracardiac anatomy, and expected somatic growth limit the types of CIED implants possible for pediatric and congenital heart disease (CHD) patients. These patients demonstrate higher CIED-related complication rates compared with adults. As the number of pediatric and CHD patients who require CIEDs increases, so does the need for advocacy. Fortunately, collaboration among the Food and Drug Administration, industry, and pediatric societies has led to the improvement of regulations and support for clinical trials.

Arrhythmias in Williams Syndrome.

Williams syndrome (WS) is a congenital, multisystem disorder in which 80% of patients have cardiovascular abnormalities. Sudden cardiac death occurs 25 to 100 times more often in WS than in the general population, and cardiac repolarization is abnormal in WS. We sought to determine the prevalence of primary arrhythmias in patients with WS and whether QTc prolongation impacts arrhythmia risk. We retrospectively reviewed all patients with WS with ambulatory electrocardiogram (ECG) monitoring at our institution between October 2017 and January 2022. The primary outcome was the presence of arrhythmia. Predictors pre-determined for analysis included premature ventricular and atrial complex burden (%), degree of QTc change with varying heart rates, intervals and rhythm on 12-lead ECG, age, gender, symptomatology, and clinical and surgical history. A total of 74 patients (55% female, median age 8 years (3, 13) underwent 108 ambulatory monitors. Arrhythmias were present in 9 patients (12%). Within this group of 9 patients, 18/24 serial monitors were abnormal, and 3/9 patients (33%) had >1 arrhythmia type. Older age (p = 0.002) and symptoms (syncope, p = 0.005) were associated with arrhythmias. Arrhythmia was not associated with the degree of structural heart disease. Atrial tachycardia was the most identified arrhythmia (n = 6; 67% of patients with arrhythmias and 8% of the total cohort). The QTc abnormally increased with higher heart rates in all groups. There was a higher number of premature ventricular and atrial complexes per hour in patients with arrhythmias. In conclusion, atrial arrhythmias were the most common arrhythmia in patients with WS and routine ambulatory ECG and intermittent rhythm monitoring are indicated in WS, particularly given the high risk of sudden cardiac death in WS.

Outcomes After Development of Ventricular Arrhythmias in Single Ventricular Heart Disease Patients With Fontan Palliation.

BACKGROUND: With the advent of more intensive rhythm monitoring strategies, ventricular arrhythmias (VAs) are increasingly detected in Fontan patients. However, the prognostic implications of VA are poorly understood. We assessed the incidence of VA in Fontan patients and the implications on transplant-free survival. METHODS: Medical records of Fontan patients seen at a single center between 2002 and 2019 were reviewed to identify post-Fontan VA (nonsustained ventricular tachycardia >4 beats or sustained >30 seconds). Patients with preFontan VA were excluded. Hemodynamically unstable VA was defined as malignant VA. The primary outcome was death and heart transplantation. Death with censoring at transplant was a secondary outcome. RESULTS: Of 431 Fontan patients, transplant-free survival was 82% at 15 years post-Fontan with 64 (15%) meeting primary outcome of either death (n=16, 3.7%), at a median 4.6 (0.4-10.2) years post-Fontan, or transplant (n=48, 11%), at a median of 11.1 (5.9-16.2) years post-Fontan. Forty-eight (11%) patients were diagnosed with VA (90% nonsustained ventricular tachycardia, 10% sustained ventricular tachycardia). Malignant VA (n=9, 2.0%) was associated with younger age, worse systolic function, and valvular regurgitation. Risk for VA increased with time from Fontan, 2.4% at 10 years to 19% at 20 years. History of Stage 1 surgery with right ventricular to pulmonary artery conduit and older age at Fontan were significant risk factors for VA. VA was strongly associated with an increased risk of transplant or death (HR, 9.2 [95% CI, 4.5-18.7]; P<0.001), with a transplant-free survival of 48% at 5-year post-VA diagnosis. CONCLUSIONS: Ventricular arrhythmias occurred in 11% of Fontan patients and was highly associated with transplant or death, with a transplant-free survival of <50% at 5-year post-VA diagnosis. Risk factors for VA included older age at Fontan and history of right ventricular to pulmonary artery conduit. A diagnosis of VA in Fontan patients should prompt increased clinical surveillance.

Utility of smart watches for identifying arrhythmias in children.

BACKGROUND: Arrhythmia symptoms are frequent complaints in children and often require a pediatric cardiology evaluation. Data regarding the clinical utility of wearable technologies are limited in children. We hypothesize that an Apple Watch can capture arrhythmias in children. METHODS: We present an analysis of patients ≤18 years-of-age who had signs of an arrhythmia documented by an Apple Watch. We include patients evaluated at our center over a 4-year-period and highlight those receiving a formal arrhythmia diagnosis. We evaluate the role of the Apple Watch in arrhythmia diagnosis, the results of other ambulatory cardiac monitoring studies, and findings of any EP studies. RESULTS: We identify 145 electronic-medical-record identifications of Apple Watch, and find arrhythmias confirmed in 41 patients (28%) [mean age 13.8 ± 3.2 years]. The arrythmias include: 36 SVT (88%), 3 VT (7%), 1 heart block (2.5%) and wide 1 complex tachycardia (2.5%). We show that invasive EP study confirmed diagnosis in 34 of the 36 patients (94%) with SVT (2 non-inducible). We find that the Apple Watch helped prompt a workup resulting in a new arrhythmia diagnosis for 29 patients (71%). We note traditional ambulatory cardiac monitors were worn by 35 patients (85%), which did not detect arrhythmias in 10 patients (29%). In 73 patients who used an Apple Watch for recreational or self-directed heart rate monitoring, 18 (25%) sought care due to device findings without any arrhythmias identified. CONCLUSION: We demonstrate that the Apple Watch can record arrhythmia events in children, including events not identified on traditionally used ambulatory monitors.

Wearable devices, such as smart watches, have become popular for the monitoring of health, particularly for people with heart conditions. Wearable devices have been well-studied in adults, however there is less information available on their effectiveness in monitoring children's health. We reviewed the heart electrical recordings of a group of children who submitted recordings obtained from their Apple Watches during moments when they felt as though their heart's rhythm was abnormal. The Apple Watches captured rhythm abnormalities that matched the diagnoses obtained using heart monitors used clinically. This study shows that use of Apple Watches can enable clinicians to identify abnormalities that many traditional at-home monitoring devices do not detect. Thus, wearable devices, such as the Apple Watch, could be used to help identify heart rhythm disorders in children.

Criteria for Early Pacemaker Implantation in Patients With Postoperative Heart Block After Congenital Heart Surgery.

BACKGROUND: Guidelines recommend observation for atrioventricular node recovery until postoperative days (POD) 7 to 10 before permanent pacemaker placement (PPM) in patients with heart block after congenital cardiac surgery. To aid in surgical decision-making for early PPM, we established criteria to identify patients at high risk of requiring PPM. METHODS: We reviewed all cases of second degree and complete heart block (CHB) on POD 0 from August 2009 through December 2018. A decision tree model was trained to predict the need for PPM amongst patients with persistent CHB and prospectively validated from January 2019 through March 2021. Separate models were developed for all patients on POD 0 and those without recovery by POD 4. RESULTS: Of the 139 patients with postoperative heart block, 68 required PPM. PPM was associated with older age (3.2 versus 1.0 years; P=0.018) and persistent CHB on POD 0 (versus intermittent CHB or second degree heart block; 87% versus 58%; P=0.001). Median days [IQR] to atrioventricular node recovery was 2 [0-5] and PPM was 9 [6-11]. Of the 100 cases of persistent CHB (21 in the validation cohort), 59 (59%) required PPM. A decision tree model identified 4 risk factors for PPM in patients with persistent CHB: (1) aortic valve replacement, subaortic stenosis repair, or Konno procedure; (2) ventricular L-looping; (3) atrioventricular valve replacement; (4) and absence of preoperative antiarrhythmic agent (in POD 0 model only). The POD 4 model specificity was 0.89 [0.67-0.99] and positive predictive value was 0.94 [95% CI 0.81-0.98], which was stable in prospective validation (positive predictive value 1.0). CONCLUSIONS: A data-driven analysis led to actionable criteria to identify patients requiring PPM. Patients with left ventricular outflow tract surgery, atrioventricular valve replacement, or ventricular L-Looping could be considered for PPM on POD 4 to reduce risks of temporary pacing and improve care efficiency.