Dissertation Thuy Mi Nguygen

Public defence: Thuy Mi Tran Nguyen - Institute of Clinical Medicine

Trial lecture

Title: Sex differences in structural heart disease and sudden cardiac death prevention

Time: 10.15

Place: Seminarrom 3 B1.1017, Rikshospitalet

Dissertation

Title: Long-Term Outcomes and Temporal Trends In Primary Prevention ICD Selection in Non-Ischemic Dilated and Ischemic Cardiomyopathy

Time: 13.15

Place: Seminarrom 3 B1.1017, Rikshospitalet 

Summary

Cardiovascular diseases remain the leading cause of mortality and morbidity in the Western world. This doctoral thesis focuses on ischemic heart disease, heart failure, and risk stratification for sudden cardiac death.

The main objective was to assess long-term outcomes after myocardial infarction and heart failure, evaluate the impact of changes in guideline-directed use of primary prophylactic implantable cardioverter-defibrillators (ICDs), and investigate whether advanced echocardiographic parameters improve the prediction of life-threatening ventricular arrhythmias beyond left ventricular ejection fraction (LVEF).

The thesis is based on three observational studies with long-term follow-up. Data were obtained from cohorts of patients with ST-elevation and non-ST-elevation myocardial infarction, as well as patients with ischemic and non-ischemic cardiomyopathy receiving primary prophylactic ICDs. Echocardiographic assessment included conventional measures of left ventricular systolic function and strain-based parameters, particularly global longitudinal strain (GLS) and mechanical dispersion (MD). Outcomes included all-cause mortality and documented ventricular arrhythmias or ICD therapy.

The first study demonstrated a significant reduction in short- and long-term mortality after ST-elevation myocardial infarction over the past decade, whereas no comparable improvement was observed in non-ST-elevation myocardial infarction. The second study showed that changes in clinical practice following the DANISH trial resulted in younger non-ischemic cardiomyopathy patients with higher LVEF receiving ICDs, without a corresponding reduction in mortality or ICD therapies. In contrast, fewer ICD therapies were observed in ischemic cardiomyopathy after 2017. The third study demonstrated that GLS and MD were superior to LVEF in predicting life-threatening ventricular arrhythmias in both ischemic and non-ischemic cardiomyopathy. Patients with non-ischemic cardiomyopathy and normal MD had very low arrhythmic risk, while ischemic cardiomyopathy patients with increased MD had the highest risk.

Overall, these findings highlight the need for more refined risk stratification and targeted therapeutic strategies in patients with non-ST-elevation myocardial infarction. Moreover, integrating heart failure etiology with strain-based echocardiographic parameters may further improve risk assessment and facilitate more individualized decision-making regarding ICD implantation.