Evaluation and prognostic significance of premature ventricular contractions in patients without structural heart disease
Abstract: Introduction: Premature ventricular contractions (PVCs) are a common form of arrhythmia associated with poor prognosis in patients with structural heart disease. However, their prognostic impact on healthy individuals is unclear. There is also a lack of evidence about risk stratification of this group through cardiac imaging and electrocardiographic features. With this project we wanted to study whether patients with PVCs in which structural heart disease had thoroughly been excluded, have a worse prognosis than a control population. Moreover, we wanted to investigate whether PVC morphology and/or PVC duration are associated with the clinical outcome. Finally, we explored whether cardiac magnetic resonance imaging (CMR) and advanced echocardiographic parameters could unmask signs of structural heart disease in patients with high PVC-burden and normal echocardiogram. Methods: To study the prognostic impact of PVCs, we identified 807 patients with no history of structural heart disease, normal echocardiography and exercise test and verified PVCs. During a follow-up period of 5.2 years, we compared the clinical outcome–in terms of total mortality and cardiovascular morbidity–with a population matched by sex and age. To explore whether electrocardiographic features have a prognostic significance among healthy PVC-patients, we identified 541 patients to which we had access to PVC recording on 12-lead ECG and analysed PVC morphology and QRS width. For the studies focusing on diagnostic evaluation through advanced cardiac imaging, we included patients with a PVC burden of at least 10,000 beats/day and with normal results at exercise test and echocardiography. They underwent additional investigation with CMR (study 2) or advanced echocardiographic parameters that are normally not included in clinical praxis (study 3). Results: Healthy PVC-patients had a generally favourable prognosis, showing no worse clinical outcome than the sex- and age-matched control group that had not undergone investigation to rule out heart disease. However, patients with high PVC-burden showed signs of myocardial dysfunction when advanced imaging techniques were used, despite normal results at standard investigation that included echocardiogram. Sub-group analysis based on PVC-morphology showed that PVC originating from the outflow tract and the right ventricle was associated with a more favourable prognosis than intra cavity- and left ventricular PVCs respectively. Analysis of PVC-duration– measured as QRS-width during PVC–showed no impact on clinical outcome. Conclusions: PVC patients who had undergone a thorough medical examination with normal results did not have a worse outcome than matched controls during a median follow-up time of 5.2 years. PVC duration did not seem to be associated with the clinical outcome in our study including 541 patients with different sites of origin. However, PVCs with a morphology originating from the outflow tract and the right ventricle were associated with a better outcome. CMR and comprehensive advanced echocardiography could identify signs of myocardial dysfunction in patients with high PVC burden and normal findings at standard echocardiography. The clinical significance of these imaging findings needs to be assessed by larger longitudinal studies.
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