It is intriguing why there are no new drugs targeting adenosine receptors able to combat heart diseases, especially after the finding that adenosine A2A receptor (A2AR) antagonists, which are safe, are efficacious in reverting abnormal calcium handling in cells from patients with atrial fibrillation [82,83,84], a disease lacking efficacious medication. The gene discussed is ADORA2A; the disease is heart disorder.