If no other pacemaker begins pacing during an episode of sinus arrest it becomes a cardiac arrest. This condition is sometimes confused with sinoatrial block, a condition in which the pacing impulse is generated, but fails to conduct through the myocardium. Differential diagnosis of the two conditions is possible by examining the exact length of the interruption of cardiac activity.
If no other pacemaker assumes control during an episode of cardiac standstill, it evolves into a full-blown cardiac arrest. This condition is sometimes misidentified with sinoatrial block, where the heartbeat originates but fails to propagate through the heart muscle. A precise examination of the duration of the interruption in cardiac rhythm can facilitate differentiation between the two conditions.