Effectiveness of a simple medication adjustment protocol for optimizing peri-cardioversion rate control: A derivation and validation cohort study.

BACKGROUND: Rate control medications are foundational in the management of persistent atrial fibrillation (AF). There are no guidelines for adjusting these medications prior to elective direct-current cardioversion (DCCV). OBJECTIVE: To derive and validate a preprocedural medication adjustment protocol that maintains peri-DCCV rate control and minimizes risk of postconversion bradycardia, pauses, need for pacing, and cardiopulmonary resuscitation (CPR). METHODS: Consecutive patients with persistent AF awaiting elective DCCV across 2 hospitals were screened for inclusion into derivation, validation, and control cohorts. In the derivation cohort, each patient taking an atrioventricular (AV) nodal blocker had medications adjusted based on heart rate (HR) 2 days before DCCV, and the magnitude of dose adjustment was compared with peri-DCCV HR. The adjustment protocol that achieved the highest percentage of optimal peri-DCCV rate control was tested prospectively in the validation cohort and compared to a standard-of-care control group. RESULTS: The optimal protocol from the derivation cohort (n = 71), based on the 2-day pre-DCCV HR, was to (1) CONTINUE AV nodal blocker for HR ≥ 100 beats per minute (bpm), (2) reduce dose by ONE increment when 80-99 bpm, (3) reduce dose by TWO increments when 60-79 bpm, and (4) HOLD when <60 bpm. In the prospective validation cohort (n = 106), this protocol improved peri-DCCV rate control (82% vs 62%, P < .001) compared to current standard of care (n = 107). There were no conversion pauses ≥5 seconds, need for pacing, or CPR post-DCCV. CONCLUSION: This simple preprocedural medication adjustment protocol provides an effective strategy of optimizing peri-DCCV rate control in patients with AF.

Establishing reference ranges for ambulatory electrocardiography parameters: meta-analysis.

OBJECTIVE: Despite the widespread and increasing use of ambulatory electrocardiography (ECG), there is no consensus on reference ranges for ambulatory electrocardiogram parameters to guide interpretation. We sought to determine population distribution-based reference ranges for parameters measured during ambulatory electrocardiogram in healthy adults, based on existing literature. METHODS: We searched multiple databases from 1950 to 2020. Articles reporting original data from ≥24-hour ambulatory electrocardiogram monitoring in healthy adults were included. Data extraction and synthesis were performed according to Meta-analysis of Observational Studies in Epidemiology guidelines. The prevalence/mean and SD for common parameters (sinus pauses, conduction abnormalities and ectopy) were extracted by age group (18-39, 40-59, 60-79 and 80+ years). RESULTS: We identified 33 studies involving 6466 patients. Sinus pauses of >3 s were rare (pooled prevalence <1%) across all ages. Supraventricular ectopy of >1000/24 hours increased with age, from 0% (95% CI 0% to 0%) in those aged 18-39 years to 6% (95% CI 0% to 17%) in those aged 60-79 years. Episodes of supraventricular tachycardia increased from 3% (95% CI 1% to 6%) in those aged 18-39 years to 28% (95% CI 9% to 52%) in those aged 60-79 years. Ventricular ectopy of >1000/24 hours also increased with age, from 1% (95% CI 0% to 2%) in those aged 18-39 years to 5% (95% CI 1% to 10%) in those aged 60-79 years. Episodes of non-sustained ventricular tachycardia ranged from 0% (95% CI 0% to 1%) in those aged 18-39 years to 2% (95% CI 0% to 5%) in those aged 60-79 years. CONCLUSION: Despite the limitations of existing published data, this meta-analysis provides evidence-based reference ranges for ambulatory electrocardiogram parameters and highlights significant age-dependent differences that should be taken into account during interpretation.

Single-centre use of implantable loop recorders in patients with congenital heart disease.

AIMS: To determine the efficacy of the implantable loop recorder (ILR) in patients with congenital heart disease. METHODS AND RESULTS: Retrospective data analyses of all patients with congenital heart disease undergoing ILR implantation in a congenital cardiac centre. Of 78 ILRs implanted between July 2000 and October 2007, 22 (15 male) patients had congenital heart disease. The median age at implantation was 15.5 years (7.0-46.5). Six patients had neurodevelopmental delay. Indications for implantation were syncope (n = 15), palpitations (n = 4), and pre-syncope (n = 3). Median implantation time was 19 months (1-30). Explantation data were available in 16 patients (73%). Implantable loop recorders were explanted following establishment of positive diagnosis (n = 3), negative diagnosis (n = 7), and at the end of battery life (n = 4). One patient died with the ILR in situ. One device eroded after 2 months without further complication. Following ILR interrogation, diagnosed arrhythmias included ventricular tachycardia (n = 2) and sinus node dysfunction (n = 1). On the basis of these findings, two patients had intracardiac defibrillators and one patient had a dual-chamber pacemaker implanted. CONCLUSION: Implantable loop recorders lead to a positive or negative arrhythmic diagnosis following explantation in 71% of patients with congenital heart disease. This is particularly beneficial in patients with neurodevelopmental delay where accurate history is often limited.

Outcomes of untreated frequent premature ventricular complexes with normal left ventricular function.

OBJECTIVE: The natural history of frequent premature ventricular complexes (PVCs) in association with preserved left ventricular ejection fraction (LVEF) is uncertain. The optimal management of this population is thus undefined. We studied the outcomes of untreated patients with frequent PVCs and preserved LVEF. METHODS: This cohort study prospectively evaluated consecutive patients from 2012 to 2017, with asymptomatic or minimally symptomatic frequent idiopathic PVCs (≥5% PVCs in 24 hours; normal LVEF; no cause identified on comprehensive evaluation). No suppressive therapy (ablation or antiarrhythmic drugs) were used and patients were followed with serial ambulatory ECG monitoring and echocardiography. The primary arrhythmic outcome was reduction in PVC burden to <1% on serial ambulatory monitoring. The primary echocardiographic outcome was a reduction of LVEF to <50%. RESULTS: One hundred patients met inclusion criteria (mean age 51.8 years, 57% female) with a median PVC burden of 18.4%. Reduction to <1% PVCs occurred in 44 of 100 patients (44.0%) at a median of 15.4 months (range 2.6 to 64.3). Recurrence was uncommon (4/44, 9.1%). Four patients (4.3%) with a persistently elevated PVC burden developed left ventricular dysfunction (LVEF <50%) during the follow-up period at a range of 53-71 months. The initial PVC burden did not predict subsequent resolution (HR 1.00(0.97, 1.03); p=0.86). CONCLUSIONS: A strategy of active surveillance is appropriate for the majority of patients with frequent idiopathic PVCs in association with preserved LVEF, owing to the low risk of developing left ventricular systolic dysfunction and the high rate of spontaneous resolution.

Charting a course for cardiac electrophysiology training in Canada: the vital role of fellows in advanced cardiovascular care.

Canadian electrophysiology (EP) fellowship programs have evolved in an ad hoc fashion over 30 years. This evolution has occurred in many fields in medicine and is natural when innovators and pioneers attract research fellows who help change the status quo from predominantly research to a predominantly clinical application and focus. Fellows not only push their supervisors and their centres into new areas of inquiry but also function at the most advanced level to encourage and teach junior trainees and to provide examples of excellence to residents, medical students, and other health professionals. Funding for fellows has never been provided in the traditional way through the Ministry of Health or the Ministry of Advanced Education. Each Canadian centre has over the years found novel ways to fund fellowship programs, and many centres have used value-adds from procurement programs. These sources of funding are eroding as provincial government agencies are beginning to assume procurement responsibilities and local flexibility to fund fellowships is lost. In particular, provincial government agencies feel that valuable financial resources should be restricted to Canadian trainees only, despite the international consensus that fellowship is an essential time for advanced trainees to travel abroad to acquire a broad a range of experience, learn new techniques and approaches, make lifelong research connections, and hopefully return home with these skills and expertise. This article summarizes the long history of EP fellowship training in Canada, as well as EP fellowship experiences at home and abroad by Canadian electrophysiologists, in an attempt to contextualize these new realities.

Short-term outcome of infants presenting to pediatric intensive care unit with new cardiac diagnoses.

AIMS: To outline the etiology, clinical course, short-term survival to discharge and neurological outcome of infants (<1 yr) with new cardiac diagnoses presenting to a pediatric intensive care (PICU) unit with acute cardiac compromise. METHODS: Retrospective search of a computerized database and medical case notes for all acute cardiac admissions to PICU from June 2001 to 2006. Pre-existing hospital-based patients with new cardiac diagnoses were excluded. RESULTS: Seventy patients were identified, 38 (54%) of whom were male. There were six main subgroups: obstructive left heart lesions (n= 20), transposition of the great arteries (TGA) (n= 9), total anomalous pulmonary venous drainage (TAPVD) (n= 7), dilated cardiomyopathy (n= 11), arrhythmia (n= 12), and others (n= 11). Fifty-nine patients (84%) were external referrals to our center. The median age at presentation was 13.5 days (0-272) with median duration of symptoms of 1 day (0-21). The median base deficit at presentation was -7.6 mEq/L (-43 to +4.2). Fifty-three patients (76%) required respiratory support with a median duration of ventilation of 4 days (1-49). Fifty-six patients (80%) required inotropic support. The median PICU stay was 7 days (1-64) with a median total hospital stay of 16 days (1-71). Six patients (9%) died prior to discharge. Of the survivors 7 (11%) had seizure activity or evolving clinical neurological abnormalities. CONCLUSIONS: Cardiovascular compromise due to previously unrecognized congenital or acquired heart disease is associated with clinically significant morbidity and mortality. Longer term follow-up is required to evaluate the initial effect of poor cardiac output and hypoxia on long-term neurodevelopmental outcome.

Acquired stenosis of normally connected pulmonary veins.

Pulmonary venous stenosis has been a challenge to paediatric cardiologists and surgeons. In spite of significant improvements in the management and outcome of various congenital cardiac problems, the prognosis of this condition continues to be dismal. Acquired stenosis of the pulmonary veins has been described in the adult population, especially after radiofrequency ablation for atrial arrhythmias. The outcome of this condition has generally been described to be favourable in the long term. Acquisition of pulmonary venous stenosis in childhood has a very different outcome, and is not a very well recognised entity, with symptoms and signs which are non-specific. We present 7 infants who, when first assessed, had normal pulmonary veins, but who subsequently acquired stenoses of the veins, with very significant resultant morbidity and mortality.

Terminal arrhythmia in a patient with Mustard's operation.

In spite of significant improvements in outcome, adults surviving the Mustard procedure continue to be at risk of premature death, cardiac failure, and arrhythmias. Primary ventricular fibrillation as a cause of sudden death in these patients may not be uncommon, and implantation of a defibrillator should be considered, particularly if there is systemic ventricular dysfunction and pre-existing heart block.