Shiv Sena executive president Uddhav Thackeray will undergo an angioplasty at the Lilavati Hospital in Mumbai on Friday to remove blockages in his arteries.
Uddhav's estranged cousin and MNS chief Raj Thackeray was also at the hospital.
Uddhav had undergone an angiography on July 16 which had revealed three blockages.
There were reports that the Lilavati medical team had strongly recommended a bypass surgery as angiography had shown three blockages.
Meanwhile, Shiv Sainiks have organised a 'puja' at the Siddhivinayak Temple at Prabha Devi in Central Mumbai to pray for Uddhav's speedy recovery.
The doctors had briefed Uddhav's father Balasaheb Thackeray on Monday on his son's medical condition.
At the time of angiography, Raj had visited him at Lilavati and later drove him to Matoshree bungalow, the Thackeray family home in suburban Bandra.
This led to speculation in political circles about a political reconciliation between the warring cousins but Sena sources said there was no politics involved.