E possibile predire l'effetto antiaritmico dei betabloccanti in base al riconoscimento di differenti relazioni tra battiti prematuri ventricolari ed il precedente ciclo cardiaco?

The aim of our study was to correlate betablocker effects on premature ventricular beats (PVBs) with different patterns between PVB frequency and cardiac cycle. The computer program we used correlates each PVB to the preceding cycle length in a 24-hour electrocardiogram recording. The arrhythmic patterns obtained were defined as tachycardia-dependent, indifferent and bradycardia-dependent. We selected 51 patients (39 males, 12 females, mean age 52 years) with different cardiac diseases, all in sinus rhythm, with > 25 PVBs/h, characterized by PVB stability and reproducible pattern in 2 Holter monitoring recorded at a 3-5 day interval. A tachycardia-dependent pattern (TDP) was demonstrated in 20 patients; 22 patients showed an indifferent pattern (IP) and 9 a bradycardia-dependent pattern (BDP). A third Holter monitoring was performed 4-5 days after nadolol administration (80 mg/day). Nadolol caused a 87.7% PVB suppression in TDP patients (p <0.001), a 34.8% PVB reduction in IP patients (p <0.01) and a 36.3% increase in BDP patients (NS). The different effect of nadolol on these groups was highly significant (chi 2 30.9; p <0.0001). These results indicate that pattern definitions is useful in identifying PVB subsets which are likely to be improved, or not, by betablockers.