MOSCOW (AP) _ Soviet President Konstantin U. Chernenko died after a lengthy battle with the lung disease emphysema, complicated by heart and kidney ailments, the official news agency Tass said today.

Tass and other Soviet media reported today that Chernenko, 73, died Sunday evening. Hours later Tass said Chernenko had suffered from emphysema, a disease that involves abnormal distention of lung cells, causing loss of elasticity in the tissues and making it difficult to breathe.

Chernenko's lung condition was complicated by unspecified cardiac difficulties and chronic hepatitis that worsened into cirrhosis, or deterioration, of his kidneys, Tass said.

Despite treatment, Chernenko's tissues and organs began to degenerate, and he died of ''increasing kidney, cardiac and lung insufficiencies,'' the news agency said.

The Tass report was signed by chief Kremlin physician Yevgeny Chazov and other leading Soviet physicians.