The Chilean Rose Tarantula is the source of an important protein used in drugs to stop atrial fibrillation, an abnormal heart rhythm, or cardiac arrhythmia, which can result in death. Atrial fibrillation prevents the heart's atria from efficiently pumping blood by disrupting their beating rhythm, causing the blood to clot within the chambers. A piece of clot that breaks off and enters the brain can become lodged in an artery, triggering a stroke.

A team of researchers at the University of Buffalo discovered a peptide (a protein building block), GSMtx-4, in the tarantula's venom that prevents fibrillation by blocking the activity of certain gate-like structures of neurons in the heart. These "channels" can become overstimulated when an individual suffers from a heart disease like congestive heart failure.

Other experiments have since shown that the peptide could be used as an analgesic to reduce pain. No drug that uses GSMtx-4 is yet available, but the scientists hope to begin development on one in the near future.