Abstract: Sino-atrial node cells (SNCs) are the basis of sinus node pacemaker activity, maintaining normal cardiac activity. Sick sinus syndrome (SSS) is one of the most common cardiovascular diseases, mainly resulting from sinus pacing and/or conduction disorders caused by sinus node dysfunction due to the spontaneous action potential abnormalities of sinus node pacemaker cells. Sodium calcium exchanger 1 (NCX1) plays an important role in SNCs action potentials generation and maintenance process, the dysfunction of which can lead to sinus node dysfunction resulting in SSS.