The present invention is a cardiac rhythm-monitoring device, which allows patients to perform a preliminary screening for supraventricular arrhythmia. The device detects beat-to-beat heart rhythms (i.e. the R--R interval between individual heart beats) and performs a screening test to determine if there are indications of arrhythmia. The test looks for variance in the R--R interval that is outside of the normal range, either using a pre-constructed chart based upon general population studies to determine the normal range of variance or using normal distribution analysis of the patient's own heart rhythm to determine the normal range of variance for determining irregular heartbeats, and if there are multiple irregularities within the sensed time frame, the patient is warned of potential supraventricular arrhythmia. By sensing both electrical impulses form the heart and mechanical responses to the heartbeat, the device may augment its analysis.