ClinicalSudden DeathDefining idiopathic ventricular fibrillation: A systematic review of diagnostic testing yield in apparently unexplained cardiac arrest
Introduction
Apparently unexplained cardiac arrest (UCA) is diagnosed when patients presenting with cardiac arrest are found to have no obstructive coronary artery disease, normal left ventricular systolic function, and a baseline electrocardiogram that does not identify the cause of cardiac arrest. Finding the cause of UCA is important as it guides family screening and has therapeutic and prognostic implications for probands. Multiple studies have established the role of comprehensive diagnostic testing in revealing a concealed cause of UCA.1, 2, 3, 4, 5, 6 However, these studies used different protocols and reported different results. Consequently, current guidelines recommend performing comprehensive diagnostic testing in UCA probands and only diagnosing idiopathic ventricular fibrillation (IVF) when that fails to identify the cause; however, they do not provide a clear guidance as to the panel of tests that need to be performed for the comprehensive diagnostic testing to be considered complete.7 In addition, some have suggested using certain characteristics to diagnose IVF without the need to exclude other causes. This has resulted in considerable inconsistency in the literature regarding the use of the term IVF to describe UCA probands who underwent some degree of diagnostic testing.7 As such, there is a need to develop a standardized approach to UCA in order to facilitate a uniform diagnosis of IVF in these patients. Thus, we sought to perform a systematic review and meta-analysis of studies reporting the diagnostic testing yield in patients with UCA.
Section snippets
Literature search
The reporting of this review conforms to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines (see Online Supplemental Table 1 for the PRISMA checklist). A protocol was devised and registered in the International Prospective Register of Systematic Reviews (ID: CRD42020189981). The literature search strategy was developed in consultation with a medical librarian (see Online Supplemental Figure 1 for the complete search strategy). In brief, we searched MEDLINE,
Study selection and characteristics
Our search strategy revealed 3376 citations. Of these, 41 were selected for full-text review. A total of 21 studies met inclusion criteria and were included in the systematic review. Online Supplemental Figure 2 depicts the PRISMA flow diagram. Seven studies reported the yield of comprehensive diagnostic testing and 14 reported the yield of single tests.
Among studies that reported the yield of comprehensive diagnostic testing, 6 were manuscripts and 1 was an abstract. One study reflected the
Discussion
Examining the totality of experience evaluation apparently UCA, the yield of comprehensive diagnostic testing was found to be consistently high. The results of our analysis suggest that a systematic use of CMR, ETT, and SCB should be incorporated in the definition of IVF because of their high yield. More evidence is needed to determine the role of EPS, CSP, and systematic genetic testing.
The significant differences in the conditions diagnosed after comprehensive diagnostic testing of UCA
Conclusion
Based on our systematic review, a comprehensive evaluation of an apparently UCA leads to a diagnosis in 43% of patients. We propose a standardized algorithm for the diagnostic evaluation of UCA, which can serve to assess the strength of an IVF diagnosis. This promises to facilitate a more uniform use of the term IVF in the literature. Given the imperfect features of each test and the corresponding potential for false-positive results, a careful ongoing review of diagnoses made in UCA probands
Acknowledgments
We thank Sarah Visintini, BA, MLIS for her assistance with the systematic search and Margaret Sampson, MLiS, PhD, AHIP for peer reviewing the search strategy.
References (23)
- et al.
Diagnostic approach to unexplained cardiac arrest (from the FIVI-Gen Study)
Am J Cardiol
(2015) - et al.
Familial cardiological and targeted genetic evaluation: low yield in sudden unexplained death and high yield in unexplained cardiac arrest syndromes
Heart Rhythm
(2013) - et al.
Initially unexplained cardiac arrest in children and adolescents: a national experience from the Canadian Pediatric Heart Rhythm Network
Heart Rhythm
(2020) - et al.
HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes: document endorsed by HRS, EHRA, and APHRS in May 2013 and by ACCF, AHA, PACES, and AEPC in June 2013
Heart Rhythm
(2013) - et al.
Comprehensive assessment of unexplained sudden cardiac death and idiopathic ventricular fibrillation during the index hospitalization: a systematic thorough investigation to unmask specific etiology
Arch Cardiovasc Dis Suppl
(2020) - et al.
Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology
Genet Med
(2015) - et al.
The Hearts in Rhythm Organization: A Canadian National Cardiogenetics Network
CJC Open
(2020) - et al.
High prevalence of concealed Brugada syndrome in patients with atrioventricular nodal reentrant tachycardia
Heart Rhythm
(2015) - et al.
Everybody has Brugada syndrome until proven otherwise?
Heart Rhythm
(2015) - et al.
Yield and pitfalls of ajmaline testing in the evaluation of unexplained cardiac arrest and sudden unexplained death: single-center experience with 482 families
JACC Clin Electrophysiol
(2017)
Systematic assessment of patients with unexplained cardiac arrest: Cardiac Arrest Survivors With Preserved Ejection Fraction Registry (CASPER)
Circulation
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Funding sources: This research did not receive any specific grant from funding agencies in the public, commercial, or non-for-profit sectors.
Disclosures: The authors have no conflicts of interest to disclose.