Particularly in the case of uncontrolled ventricular rate, the sudden occurrence of supraventricular tachycardia leads to progressive heart failure and morphologically to the enlargement of the ventricles as well as a decline in pumping performance. Patients with pre-existing heart failure are particularly at risk. However, the tachycardia-induced cardiac dysfunction can also appear in patients without systolic or diastolic heart failure. Cardiac dysfunction is most frequently triggered by the initial occurrence of tachycardial atrial fibrillation.
Treatment is absolutely necessary and clearly indicated. In addition to a drug-induced lowering of the heart rate (e.g. with beta blockers or class III and class IV anti-arrhythmic medications), electrical cardioversion is the most effective method to restore a sinus rhythm with normal frequency. This leads to regression of the clinical and hemodynamic effects of the tachycardia on the heart and improves left ventricular systolic pump function. This regenerative effect on cardiac dysfunction with effective treatment is generally completed after four weeks. Whether the restoration of a sinus rhythm by means of electrical cardioversion improves the contractility of the left ventricle more than drug treatment alone remains to be clarified. Furthermore, the effect of the beta blocker nebivolol on heart frequency and rhythm has been shown only in experimental animal studies.
The present prospective, randomized, comparative study investigates whether electrical cardioversion with biphasic current is superior to the sole frequency-controlling treatment with nebivolol for the restoration of a normal sinus rhythm. In addition to clinical improvement, improvement in left ventricular pump function based on echocardiographic parameters is to be shown. Furthermore, it is to be documented that after electrical cardioversion a normal sinus rhythm over the long term can be achieved with continuing treatment with the beta blocker nebivolol and that effective heart rate control in the case of atrial fibrillation can be achieved with nebivolol.
Tachycardic atrial fibrillation may induce heart failure. The NEBICAR trial showed that electrical conversion into sinus rhythm as the application of betablockers (here: nebivolol) are equally well suited to restore cardiac pump function. Continuous administration of nebivolol appears to have a favourable effect on the long-term stabilization of sinus rhythm. Serum biomarkers as NT-proBNP are useful to predict and document a beneficial outcome.
Schröder M et al. Nebivolol zur Rhythmus- oder Frequenzkontrolle bei Tachykardiomyopathie – Ergebnisse der NEBICAR-Studie. Posterpräsentation bei der 75. Jahrestagung der Deutschen Gesellschaft für Kardiologie, Mannheim, 2009.
Currently, the project focuses on the assessment of the differential diagnostic and prognostic utility of various biomarkers in the treatment context of these patients.
Prof. Dr. Martin Möckel
Charité – Universitätsmedizin Berlin
Phone: +49 (0)30 450553203