Differentiation of ventricular extrasystoles on long-term ECG according to Lown classification.
| Simple ventricular extrasystoles (VES). | |
| Grade 0 | No VES |
| Grade I | <30 monomorphic VES/h |
| Grade II | > 30 monomorphic VES/h |
| Complex ventricular extrasystoles (VES). | |
| Grade IIIa | Polymorphic VES |
| Grade IIIb | Bigeminus |
| Grade IVa | Couplets |
| Grade IVb | Volleys |
| Grade V | R-on T phenomenon |
