ClinicalDevicesEffect of diurnal variations in the QRS complex and T waves on the eligibility for subcutaneous implantable cardioverter-defibrillators
Introduction
The placement of transvenous implantable cardioverter-defibrillators (TV-ICDs) is an established therapy to prevent sudden cardiac death (SCD).1, 2 Placing subcutaneous ICDs (S-ICDs) has recently become an attractive therapeutic option for patients who do not need pacing therapy, avoiding the important complications associated with transvenous leads.3 Some previous studies reported that inappropriate shocks (IASs) are associated with a reduced quality of life and increased mortality.4, 5 The propensity score matching of S-ICDs and TV-ICDs in SIMPLE and EFFORTLESS registries demonstrated similar outcomes regarding IASs at 3-year follow-up (11.9% from S-ICD vs 8.9% from TV-ICD; P = .07).6 The IDE and EFFORTLESS pooled analysis reported that IASs from S-ICDs were 24%, 39%, and 21% due to supraventricular tachyarrhythmias, T-wave oversensing (TWOS), and low-amplitude signals, respectively.7
Manufacturers have developed surface electrocardiographic (ECG) screening templates to detect incorrect QRS profile/TWOS and avoid IASs. In several previous reports, an increased body weight, increased QRS duration, right bundle branch block (RBBB), QRS-T discordance in all 3 leads (I, II, and aVF), presence of hypertrophic cardiomyopathy (HCM), and Brugada syndrome (BrS) predicted screening failure.8, 9, 10, 11, 12, 13 A previous study proposed a routine exercise screening test to reduce IASs.14 However, exercise screening cannot analyze the daily fluctuations in the QRS-T complex, which usually occur from evening to early morning, especially in patients with BrS, coronary spastic angina (CSA), and early repolarization syndrome.15, 16 Few data exist on the most frequent time of IASs from S-ICDs and the clinical effect of diurnal variations in the QRS complex and T waves on S-ICD eligibility. This study aimed to elucidate the additional effect of diurnal variations in the QRS complex and T waves using 24-hour Holter monitoring on S-ICD eligibility as well as characteristics of ineligible patients.
Section snippets
Study subjects
This analysis included data from a prospective, multicenter, observational study performed at the Japanese Red Cross Musashino Hospital and National Disaster Medical Center. We assessed consecutive patients with TV-ICDs implanted for primary or secondary prevention of SCD who attended routine follow-ups at the ICD clinics between January 2016 and January 2018. Most patients had primary cardiomyopathy, including inherited primary arrhythmia syndromes. The remaining patients presented with
Results
During the study period, all patients (n = 204) implanted with TV-ICDs were screened for inclusion in the study. We excluded patients who were older than 80 years (n = 12), were pacemaker dependent, had an indication for pacing during implantation (n = 78) or resynchronization pacing (n = 18), or had failed to complete the exercise test (n = 10) (Figure 3). Three of 6 patients with long QT syndrome were excluded because they developed bradycardia on β-blockers or we needed to perform atrial
Discussion
To our knowledge, this is the first attempt to systematically evaluate the extent to which the Holter ECG can be used to assess the eligibility for S-ICD in patients with prior TV-ICD implantation who do not need bradycardia pacing. The main findings of this study were as follows:
- 1.
Through Holter screening, we found an additional 24.4% of patients with TV-ICDs who were ineligible for S-ICD implantation.
- 2.
Regarding TWOS, the number of vectors failing screening was the largest during 0–6 AM for each
Conclusion
This prospective multicenter study firstly evaluated the effect of diurnal variations in the QRS complex and T waves on the eligibility for S-ICD. A quarter of patients with TV-ICDs, who initially appeared eligible by conventional and exercise screening ECGs, became ineligible during Holter screening. The detection of a diurnal variation through Holter monitoring and an optimized vector selection might be useful in improving the discrimination capability to determine the ineligibility for S-ICD
Acknowledgments
We thank John Martin, for providing English language editing services.
References (28)
- et al.
Executive summary: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes
J Arrhythm
(2014) - et al.
Implantable cardioverter-defibrillator therapy in Brugada syndrome: a 20-year single-center experience
J Am Coll Cardiol
(2015) - et al.
Inappropriate implantable cardioverter defibrillator shocks in MADIT II: frequency, mechanisms, predictors, and survival impact
J Am Coll Cardiol
(2008) - et al.
Safety and efficacy of the totally subcutaneous implantable defibrillator: 2-year results from a pooled analysis of the IDE study and EFFORTLESS registry
J Am Coll Cardiol
(2015) - et al.
Use of an electrocardiographic screening tool to determine candidacy for a subcutaneous implantable cardioverter-defibrillator
Heart Rhythm
(2014) - et al.
Role of exercise electrocardiogram to screen for T-wave oversensing after implantation of subcutaneous implantable cardioverter-defibrillator
Heart Rhythm
(2017) - et al.
Prevalence of subcutaneous implantable cardioverter-defibrillator candidacy based on template ECG screening in patients with hypertrophic cardiomyopathy
Heart Rhythm
(2016) - et al.
Complete right bundle branch block and QRS-T discordance can be the initial clue to detect S-ICD ineligibility
J Cardiol
(2017) - et al.
Seasonal, weekly, and circadian distribution of ventricular fibrillation in patients with J-wave syndrome from the J-PREVENT registry
J Arrhythm
(2015) - et al.
Prevalence of type 1 Brugada electrocardiographic pattern evaluated by twelve-lead twenty-four-hour Holter monitoring
Am J Cardiol
(2015)