If I remember back (10+ years, LOL) Some schools or profs within my school said "related to" and others said "secondary to" The OP has the first parts of the dx just needs the "as evidenced by" or "as manifested by" (cool extremities, faint pulses, edema, adventitious breath sounds, tachycardia, mental status, hypOtension...)
Wait, I just re-read it. I see there is an AEB but I would change that. Those are all causes of decreased CO along with the afib.
L8RRN's "altered contractility of the heart" works well as it covers both your Afib and CAD. How does your prof want you to use or not use diagnosis? (I personally am a Suzanne Gordon convert who thinks we should use them in part 2. But I'm not your prof!)
Also, personally, I would not use EKG showing afib, echo showing MVR, (or heart murmur) as a AEB. They are all things that alert me to possible decr CO but it is possible for a pt to have Afib and MVR and not have low CO. In other words- they are causes of decr CO, not signs. That's just food for thought.