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Inherited arrhythmogenic channelopathies and implantable cardioverter defibrillator treatment: national and age-related perspectives
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
2024 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Ärftliga arytmogena jonkanalsjukdomar och behandling med implanterbar defibrillator : nationella och åldersrelaterade perspektiv (Swedish)
Abstract [en]

Background: Long QT syndrome (LQTS), Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), Brugada syndrome (BrS), and short QT syndrome are hereditary diseases caused by mutations in genes coding for cardiac ion channels. Patients carrying these mutations may be at risk of symptoms such as syncope and sudden cardiac death (SCD). To prevent symptoms, patients need to be managed properly and this management may include prophylactic medical treatment, and the use of an implantable cardioverter defibrillator (ICD) for high-risk patients. ICD treatment has previously been shown to prevent SCD, but it also carries a risk of complications and inappropriate shocks. In these studies, we investigated ICD treatment in patients with inherited arrhythmogenic channelopathies with a focus on individual risk assessment and ICD harm.

Methods: Studies I–III are observational studies that use registries to identify patients and medical records to collect data. Studies I and III are performed with a descriptive approach that focus on phenotype, genotype, and medical treatment (Study I) and the diagnostic process and treatment over time (Study III). In Study II, we use Kaplan Meier analyses and incidence rates to assess risk scores and ICD harm. Study IV is a systematic review based on a systematic search and screening process. The data, which are synthesized without meta-analysis, are from published original works.

Results: In Studies I and II, we present data on 109 Swedish LQTS patients with a first ICD implantation between 1992 and 2013 at a median age of 39 years (range, 5–78 years). Most patients received ICD treatment after aborted cardiac arrest (n=45, 41%) and after syncope despite receiving prophylactic medical treatment, i.e., beta-blockers (n=31, 29%). However, 10 patients (9%) received ICD treatment despite being asymptomatic and 17 patients (16%) after syncope without ongoing beta-blocker treatment. The incidence rate of a first appropriate shock was 4.3 per 100 person-years. Concerning ICD harm, the incidence rate of inappropriate shocks was 3.0 per 100 person-years and the corresponding rate of complications was 7.6 per 100 person-years. Using risk scores previously proposed to our cohort, we found that the patients who received appropriate shocks still had zero points (i.e., the lowest score) from the risk score.

In Study III, 39 Swedish pediatric patients had either BrS (n=7) or CPVT (n=32). Of the 32 CPVT patients, 18 (56%) had been misdiagnosed at first; however, since 2010 only two patients received an initial misdiagnosis. The treatment in CPVT patients changed over time in accordance with current guidelines.

In Study IV, the database search (4318 references) rendered a final inclusion of 40 references, including 741 children and adolescents with inherited arrhythmogenic channelopathies. Of the patients affected by ICD harm, 20% (148/741) had inappropriate shocks and 23% (145/624) had other complications. In LQTS and CPVT patients, the percentage of patients with ICD harm was lower in studies published from 2015, than before.

Conclusion: These studies illustrate both the difficulty in pre-ICD risk stratification and its important role due to high combined rates of ICD harm. ICD treatment is an important treatment option for high-risk patients with inherited arrhythmogenic channelopathies. We found improvements in how patients have been managed over time and identified the need for future research addressing benefit and harm from ICD treatment among children and adolescents.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2024. , p. 80
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2298
Keywords [en]
Long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, risk score, implantable cardioverter defibrillator, ICD, appropriate shock, inappropriate shock, complication, children, adolescents, systematic review, Sweden
National Category
Cardiac and Cardiovascular Systems Pediatrics
Research subject
Clinical Genetics; cardiovascular disease; Medical Genetics; Medicine; Pediatrics; Cardiology
Identifiers
URN: urn:nbn:se:umu:diva-223714ISBN: 9789180703628 (print)ISBN: 9789180703635 (electronic)OAI: oai:DiVA.org:umu-223714DiVA, id: diva2:1854190
Public defence
2024-05-24, Stora Hörsalen, 5B, målpunkt P, plan 6, Norrlands universitetssjukhus, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2024-05-06 Created: 2024-04-24 Last updated: 2024-04-26Bibliographically approved
List of papers
1. Implantable cardioverter defibrillator treatment in long QT syndrome patients: a national study on adherence to international guidelines
Open this publication in new window or tab >>Implantable cardioverter defibrillator treatment in long QT syndrome patients: a national study on adherence to international guidelines
2017 (English)In: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 51, no 2, p. 88-94Article in journal (Refereed) Published
Abstract [en]

Objectives. Implantable cardioverter defibrillator (ICD) treatment is effective among long QT syndrome (LQTS) patients at a high risk of sudden cardiac death. Previous studies show that the international guidelines are not always followed, and that risk stratification may be based on genotype rather than individual risk profile. We analysed data from the Swedish ICD & Pacemaker Registry and medical records to examine how international guidelines were followed with regards to phenotype and genotype. Methods and results. ICD treatment was used in 150 Swedish LQTS patients from 1989-2013. The annual number of implantations increased over the study period. A total of 109 patients were included in the analysis. Most patients (91%) were symptomatic before the implantation. Seventy percent of patients who received ICD treatment met the 2006 Class I or Class IIa recommendations for LQTS treatment. Thirty-one percent of the LQT3 patients received ICD treatment despite being asymptomatic. Among LQT1 patients, 45% received ICD treatment after syncope despite beta-blockers. Conclusions. Thirty percent of Swedish LQTS patients with ICD received the treatment without a strong indication based on international guidelines. LQT3 patients were over-represented among asymptomatic patients. Many LQT1 patients received ICD despite the known effect of beta-blockers in this group.

Keywords
Long QT syndrome, implantable cardioverter defibrillator, guidelines, beta-blocker treatment, orted cardiac arrest, syncope
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-133734 (URN)10.1080/14017431.2016.1270463 (DOI)000395166500005 ()27936942 (PubMedID)2-s2.0-85007497525 (Scopus ID)
Available from: 2017-05-08 Created: 2017-05-08 Last updated: 2024-04-24Bibliographically approved
2. ICD harm and benefit: risk scores applied to the Swedish ICD-treated LQTS population
Open this publication in new window or tab >>ICD harm and benefit: risk scores applied to the Swedish ICD-treated LQTS population
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2022 (English)In: Scandinavian Cardiovascular Journal, ISSN 1401-7431, E-ISSN 1651-2006, Vol. 56, no 1, p. 48-55Article in journal (Refereed) Published
Abstract [en]

The use of implantable cardioverter defibrillators (ICDs) in long QT syndrome (LQTS) patients is essential in high-risk patients. However, it is sometimes used in patients without high-risk profiles for whom the expected benefit may be lower than the risk of ICD harm. Here, we evaluated ICD benefit and harm by assessing risk according to risk scores and pre-ICD clinical characteristics. Design. We studied 109 Swedish LQTS patients drawn from the Swedish ICD and Pacemaker Registry with data collected from medical records. In addition to clinical characteristics, we used two risk scores to assess pre-ICD risk, and evaluated ICD benefit and harm. Results. Twenty percent of all patients received ≥1 appropriate shock with a first appropriate shock incidence rate of 4.3 per 100 person-years. A long QTc (≥550 ms) and double mutations were significantly associated with appropriate shock. Low risk scores among patients without pre-ICD aborted cardiac arrest were not significantly associated with low risk of first appropriate shock. The incidence rates of a first inappropriate shock and first complication were 3.0 and 7.6 per 100 person-years, respectively. Conclusion. Our findings on ICD harm emphasize the importance of careful individual pre-ICD consideration. When we applied two risk scores to patients without pre-ICD aborted cardiac arrest, we could not validate their ability to identify patients with low risk of appropriate shocks and patients who were assessed as having a low risk still received appropriate shocks. This further supports the complexity of risk stratification and the difficulty of using risk scores.

Place, publisher, year, edition, pages
Taylor & Francis, 2022
Keywords
benefit, harm, implantable cardioverter defibrillator, Long QT syndrome, risk, Sweden
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-194538 (URN)10.1080/14017431.2022.2060524 (DOI)000788341300001 ()35481393 (PubMedID)2-s2.0-85128932257 (Scopus ID)
Funder
Swedish Heart Lung Foundation, 20150482Region Västerbotten, 7002996
Available from: 2022-05-09 Created: 2022-05-09 Last updated: 2024-04-24Bibliographically approved
3. Swedish pediatric patients with catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome – increased awareness enables earlier diagnosis?
Open this publication in new window or tab >>Swedish pediatric patients with catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome – increased awareness enables earlier diagnosis?
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-223708 (URN)
Available from: 2024-04-24 Created: 2024-04-24 Last updated: 2024-04-24
4. Implantable cardioverter defibrillators in children and adolescents with inherited arrhythmogenic channelopathies, a systematic review on harm from treatment
Open this publication in new window or tab >>Implantable cardioverter defibrillators in children and adolescents with inherited arrhythmogenic channelopathies, a systematic review on harm from treatment
(English)Manuscript (preprint) (Other academic)
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-223710 (URN)
Available from: 2024-04-24 Created: 2024-04-24 Last updated: 2024-04-24

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