If my calcium receptors dont function correctly and cause muscle cramping (possibly hereditary), could that also affect my heart?

Maybe: Maybe because the body is interrelated. Not sure what you mean by calcium receptors not functioning. A lot more information about you is needed to further answer this query. Calcium, magnesium and Vit D are all interrelated in the way the body functions. Consult a cardiologist about your heart concerns. They will likely get an EKG, labs, Echo stress test if needed. Then an opinion about it.