Atrioventricular (AV) dromotropathy refers to symptomatic first-degree AV block due to mechanical AV dyssynchrony. Current guidelines allow for the treatment of these patients with cardiac pacing; however, the evidence is based solely on case reports. At the Clinical Department of Cardiology at the University Medical Centre Ljubljana, we designed a prospective cross-over study to investigate the effects of electrical stimulation in patients with AV dromotropathy.
In the first part of this thesis, we compared continuous AV-optimized pacing with a back-up pacing mode, in which patients remained in their intrinsic rhythm with a prolonged PR interval. We assessed the presence of symptoms, exercise capacity, and hemodynamic echocardiographic parameters during each stimulation period. Exercise capacity was objectively defined by maximal workload and peak oxygen consumption. Echocardiographic parameters included left ventricular stroke volume, presence of mitral regurgitation, diastolic filling parameters, and the size and function of the left atrium and left ventricle. To ensure an unbiased symptom assessment, patients were blinded to the pacing periods.
In the second part of the thesis, we evaluated the role of mechanical AV dyssynchrony in selecting patients for pacing therapy. This appraisal was based on two studies conducted at other centers using computational simulations or involving patients with first-degree AV block and heart failure with reduced ejection fraction. We performed a subanalysis of the primary AV dromotropathy study, examining the prognostic significance of electrocardiographic and echocardiographic markers of AV dyssynchrony.
In the final part of the thesis, we analyzed data from a prospective registry of patients with severe first-degree AV block (PR interval > 300 ms). Over a five-year follow-up period, we assessed the incidence of AV block progression in these patients and attempted to identify predictors of disease progression.
|
