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BACKGROUND: Over the years, the patient population with congenital heart disease (CHD) has seen significant shifts. Not only has there been a global increase in the number of patients, but also a rise in their average age. These changes, driven primarily by technological and professional advancements over the last few decades, have given rise to a novel cohort of patients with distinct characteristics and care needs. The predominant challenges faced by these patients revolve around chronic heart failure and arrhythmias. This predisposition is primarily rooted in the fact that patients often exhibit diverse anatomical heart structures with variations in hemodynamics, along with scar tissue resulting from previous reparative surgeries. These factors collectively serve as crucial triggers and substrate for arrhythmias. OBJECTIVES: This retrospective study aims to determine the evolving demand for electrophysiological procedures concerning arrhythmias among adult patients with CHD from 1993 to 2023. Secondary objectives include analyzing shifting patient cohorts requiring an electrophysiological study and/or radiofrequency ablation, determining acute success rates of electrophysiological procedures, and comparing various cardiovascular risk factors and procedural characteristics to overall procedural acute success rates. These findings offer insights into the evolving management strategies for adult congenital heart disease patients. METHODS: This retrospective, single-center study includes patients (n=109), 18 years or older, who have an electronical patient file at the University Hospital of Zurich and gave informed consent. Collected variables include demographics, CHD diagnosis, relevant cardiovascular history, baseline cardiac characteristics, procedural characteristics and follow-up variables. The study period was divided into three eras, facilitating comparison between them. Data analysis was conducted using the statistical software SPSS. RESULTS: Throughout time, there has been a gradual rise in the number of patients who underwent a first electrophysiologic procedure: 9 patients between 1993 and 2002 (era 1), 32 patients from 2003 to 2012 (era 2), and 68 patients from 2013 until 2023 (era 3) (p=0.449). Among these patients, almost half of them (48.6%) underwent multiple electrophysiologic procedures, resulting in a total of 218 procedures in 109 patients. There was a substantial increase of 264% from the first to the second era, and a 200% increase from the second to the third. Within this general increase, there was also a large significant increase in the use of electro-anatomic mapping software (p<0.001). In total, more than half of the procedures (50.5%) were performed for intra-atrial reentry tachycardia and/or atrial flutter. Across the three periods, 142 out of 193 procedures (65.1%) have been acutely successful. This number increases to 161 procedures (79.8%) when including non-inducibility as well. CONCLUSION: The last decades, cohorts of adults with CHD requiring an electrophysiologic procedure have changed substantially due to the evolution of patient characteristics and aging of the patient population. Despite the rise in acute successes throughout time. It is crucial to remember that no conclusions could be drawn regarding the long-term effectiveness of ablation procedures. Therefore, another similar study has already been initiated in a tertiary care center in Belgium in order to obtain a better understanding in this.

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Sudden cardiac death (SCD) is one of the largest causes of natural mortality in the world. Even though some pathologies, such as coronary heart disease or myocardial infarction, have been often diagnosed in its victims, their appearance still cannot be used to predict SCD. Researchers are trying to find some patterns in heart activity that could anticipate this arrest of the heart and its consequences. One of the approaches considered for this aim is the analysis of heart rate variability (HRV), for which a Holter test is usually performed. This test records the heart activity of the patient for a long period of time, usually 24 hours, in order to provide information about his cardiac activity. The recorded signal is analyzed by a software, which extracts an automatic diagnosis of the patient. For the analysis of HRV, only normal sinus rhythms can be considered. Therefore, a stage of heartbeat classification is required. This HRV-based approach for SCD prediction is currently being researched in the Cardiology Department of Hospital Provincial Saturnino Lora, from Santiago de Cuba (Cuba). Although the Holter used provides a software tool which performs heartbeat classification, the cardiologists consider there is still a big room for improvement in its results. The ECG signals present low signal to noise ratio, which leads to a high number of errors in the automatic diagnosis. This errors require the doctors to carefully correct the automatic analysis. In order to acquire the signals and have direct contact with the Cuban cardiologists, two months of this research have been carried out in Santiago de Cuba. During this stay, an annotation tool was developed and used for creating a database with the Cuban signals. The main contribution of this thesis is a software tool, specifically designed for the previously mentioned hospital, that performs unsupervised heartbeat classification of ambulatory ECG signals. After a pre-processing stage, features are extracted to characterize the heartbeats. Two kinds of features are considered in this work: based on heartbeat morphology and based on the distance between heartbeats. These features are introduced in a classifier which labels the heartbeats as normal or abnormal. The use of a previous artefact detection stage has also been considered to overcome the low quality of the signals captured. These methods have been implemented in a user-interface that, besides providing an automatic heartbeat classification, allows the user to correct the results obtained.

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Introduction: Despite significant advancements in healthcare, recent trends indicate a plateau in cardiovascular disease (CVD) mortality rates. Myocardial infarction (MI) causes structural changes post-MI, predisposing individuals to ventricular arrhythmias and sudden cardiac death (SCD). Current guidelines for implantable cardioverter-defibrillators (ICD’s) only focus on the left ventricular ejection fraction (LVEF) with limited power to predict arrhythmic events. This study uses cardiac magnetic resonance imaging (cMRI) to examine structural changes, focusing on the MI-border zone (BZ) to predict ventricular arrhythmias. Methods: Seventeen patients were included, all of whom underwent cMRI shortly after suffering from an MI and had a minimal follow-up of three years. We reconstructed three-dimensional models of the left ventricular (LV) myocardium from the cMRI by manually segmenting the endocardium and epicardium. Voxel intensity data was extracted to determine myocardial volume, wall thickness, infarct size and structural patterns within the MI and BZ. Statistical analyses included Student's T-test and Receiver Operating Characteristic (ROC) analysis. Results: cMRI-based risk analysis revealed several predictors of appropriate therapy (AT) using an ROC analysis. These include LV infarct volume, myocardial volume, and thickness of the myocardium. Additionally, the infarct and border zone were structurally analyzed, which showed the intertwinement of healthy and infarcted tissue within the MI and BZ is predictive for appropriate therapy with an AUC of 0.826. LV ejection fraction did not predict AT. Discussion: Our findings support the presence of structural characteristics on cMRI as potential predictors of arrhythmogenic risk post-MI, aligning with previous studies highlighting the role of re-entry circuits within the MI and BZ. Conclusion: While the sample size is limited, our results demonstrate significant predictive value. Future research is warranted and should aim at multivariate risk stratification models and refine existing guidelines to optimize patient selection for preventive ICDs.