Hearts That Know How to Love (1967)

Utterly unaware of her life-threatening heart condition, young and fresh Anna falls head-over-heels in love with the brilliant medical student, Vagelis. However, Anna's parents, knowing that their precious only daughter is oblivious of this dangerous situation, have already planned an arranged marriage with the honest but twice-her-age cardio-thoracic surgeon, Veronis. Of course, Anna's parents oppose the young lovers' union, and one day, when Vagelis finally discovers fragile Anna's hidden secret, he decides to take matters into his own hands. Is Vagelis' love strong enough to save the life of Anna, his one true love?