A method implemented in a dual chamber cardiac rhythm management device for identifying non-sinus ventricular depolarizations following an atrial event. The PR interval for a sensed ventricular beat that occurs after either an atrial pace or an atrial sensed event is examined and if it falls into a non-physiologic range, it is classified as an ectopic beat. If the PR interval is close to a physiologic range, the RR to AA ratio and a PR interval for the current beat are compared to those for an immediately preceding beat. Attention is also paid to the morphology of the ventricular depolarization in determining whether a beat is ectopic or not.