Cardiac diseases depend on lifestyle, diet, stress, nature of occupation/ profession, etc.
So, without bothering about the above mentioned factors though they are important, in view of the question, the following will be helpful:
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Sectional Breathing
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Naadi Shuddhi Pranayama
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Ujjayi Pranayama
So far as asana is concerned, I would prefer to go for sukshama vyayama (Swami Dhirender Brahmachaari) or loosening exercises subject to stamina of the patients, rather than to go for asanas prima facie.
Prevention plays important role in rehabilitation/treatment: avoid food rich in fats and cholesterol, include more vegetables and fruits, meals should be light.
A 45 minute alongwith certain precaution and prevention - 15 minute for physical exercise covering sukshama vyayama or loosening exercises, 15 minutes for pranayama as mentioned above and 15 minutes for meditation will be enough. Proper nutrition/ diet management will be complementary to the yoga line of treatment.