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- Diamant, Ulla-Britt, 1955-
(författare)
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Long QT syndrome : studies of diagnostic methods
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: The Long QT Syndrome (LQTS) is a hereditary heart disease with risk of malignant ventricular arrhythmia and sudden cardiac death. Despite our increased knowledge about genotype and phenotype correlation we still rely on the 12-lead ECG for assessment of the QT interval and the T-wave morphology for diagnosis and risk stratification. Intra- and -inter individual variability in manually QT measurement and, e.g., difficulties in defining the end of the T-wave may impair the diagnosis of LQTS. Increased heterogeneity in ventricular repolarization (VR) may be an important factor in the arrhythmogenicity in cases of LQTS. In a LQTS founder population the same mutation is carried by numerous individuals in many families which provide a unique opportunity to study diagnostic methods, risk assessment, VR and the correlation between genotype and phenotype.Methods: Resting 12-lead ECG and vectorcardiogram (VCG) were recorded in 134 LQTS mutation carriers and 121 healthy controls, to investigate the capability and precision in measuring the QT interval. For assessment of the VR, VCG was compared in individuals with mutations in the KCNQ1 and KCNH2 gene. Genealogical and geographic studies were performed in 37 index cases and their relatives to determine if Swedish carriers of the Y111C mutation in the KCNQ1 gene constitute a founder population. To confirm kinship, haplotype analysis was performed in 26 of the 37 index cases. The age and prevalence of the Y111C mutation were calculated in families sharing a common haplotype.Results: VCG by automatic measurement of the QT interval provided the best combination of sensitivity (90%) and specificity (89%) in the diagnosis of LQTS. VCG showed no consistent pattern of increased VR heterogeneity among KCNQ1 and KCNH2 mutation carriers. Living carriers of the Y111C mutation shared a common genetic (haplotype), genealogic and geographic origin. The age of the Y111C mutation was approximately 600 years. The prevalence of living carriers of the Y111C mutation in the mid-northern Sweden was estimated to 1:1,500-3,000.Conclusion: We have shown that VCG provides a valuable contribution to the diagnosis and risk assessment of LQTS in adults and children. No consistent pattern of increased VR heterogeneity was found among the LQTS mutation carriers. The identified Swedish LQTS founder population will be a valuable source to future LQTS research and may contribute to increase our understanding of LQTS and the correlation of phenotype, genotype and modifying factors.
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| 2. |
- Höglund, Niklas, 1968-
(författare)
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Atrial fibrillation : treatment, associated conditions and quantification of symptoms
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia. There is a need for new pharmacological treatment strategies since the current antiarrhythmic drugs have a modest efficacy and may have severe side effects. Cardioversion (CV) of AF offers an opportunity to study related conditions in sinus rhythm (SR) and during AF. Since catheter ablation of AF is a symptomatic treatment, it is important to have tools for measurement of arrhythmia-related symptoms. Aims: To evaluate the effect of atorvastatin on maintaining SR after CV of persistent AF. To assess if highsensitivity C-reactive protein (hsCRP) predicts the recurrence of AF after CV in a population randomized to treatment with either atorvastatin or placebo. To quantify the symptomatic effect of left atrial catheter ablation of AF. To assess if the restoration of SR by CV, in a population with persistent AF, affects sleep apnea. Methods: Paper I: A total of 234 patients were randomized to treatment with either high dose atorvastatin or placebo prior to CV. Paper II: In a pre-specified substudy which included 128 of the patients in study I, hsCRP was analyzed before and after CV. Paper III: Umea 22 Arrhythmia Questions (U22) is a questionnaire that quantifies paroxysmal tachycardia symptoms. A total of 105 patients underwent first-time pulmonary vein isolation and answered U22 forms at baseline and follow-up 304 (SD 121) days after ablation. Paper IV: Polysomnography was performed before and after CV in 23 patients with persistent AF scheduled for elective CV. Results: Paper I: An intention-to-treat analysis with the available data, by randomization group, showed that 57 (51%) in the atorvastatin group and 47 (42%) in the placebo group were in SR 30 days after CV (OR 1.44, 95%CI 0.85–2.44, P=0.18). Paper II: HsCRP did not significantly predict recurrence of AF at 30 days. However, after adjusting for treatment with atorvastatin, hsCRP predicted the recurrence of AF (OR 1.14, 95% CI 1.01–1.27). Six months after CV, hsCRP at randomization predicted recurrence of AF in both univariate analysis (OR 1.30, 95% CI 1.06–1.60) and in multivariate logistic regression analysis (OR 1.33, 95% CI 1.06– 1.67). Paper III: The U22 scores for well-being, arrhythmia as cause for impaired well-being, derived timeaspect score for arrhythmia, and discomfort during attack detected relevant improvements of symptoms after the ablation. U22 showed larger improvement in patients undergoing only one procedure than in patients who later underwent repeated interventions. Paper IV: Obstructive sleep apnea occurred in 17/23 patients (74%), and central sleep apnea in 6/23 patients (26%). Five patients had both obstructive and central sleep apnea. SR at follow-up was achieved in 16 patients. The obstructive apnea-hypopnea index, central apneahypopnea index, and the number of patients with obstructive or central sleep apnea did not differ before and after restoration of SR. Conclusions: Atorvastatin is not a treatment option with regards to maintaining SR after CV in patients with persistent AF. HsCRP was associated with AF recurrence 1 and 6 months after successful CV of persistent AF. U22 quantifies the symptomatic improvement after AF ablation with adequate internal consistency and construct validity. Both obstructive and central sleep apneas are highly prevalent in patients with persistent AF. Obstructive sleep apneas are unaffected by the CV of AF to SR.
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| 3. |
- Sundström, Emilia, 1985-
(författare)
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Inherited arrhythmogenic channelopathies and implantable cardioverter defibrillator treatment : national and age-related perspectives
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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