Former Alice Cooper guitarist Steve Hunter is currently in hospital in Phoenix, Arizona with atrial fibrillation (the most common cardiac arrhythmia, or irregular heartbeat).
The doctors have kept him in overnight to allow medication to get his normal heart rhythm back and do tests to discover the cause.
An update to the original story adds that Steve's heart has since reverted to its normal rhythm after 19 hours.
Hunter toured with Cooper throughout 2011, but opted to leave the legendary rocker's touring band in 2012 to concentrate on solo projects.
Thanks to HenneMusic for the report.