Muthusamy, who resides near the city airport area, appeared upset for the past few days over the health condition of Jayalalithaa, undergoing treatment in a corporate hospital in Chennai since Sept 22, party sources said.
Though his wife and colleagues tried to convince him that the Chief Minister was on the path of recovery, he still appeared very upset, they said.
Police said he complained of chest pain amid rumours about Jayalaithaa's health condition and swooned. He was rushed to a nearby private hospital, where he was declared brought dead.
Doctors said he died of heart attack.