I've been an OB nurse for more than 12 years and I've seen 2 pts with PP cardiomyopathy. One that was diagnosed almost immediately after delivery and another who wasn't diagnosed for about 3 weeks after delivery. The problem with diagnosis is that it often depends on the severity of the disease and/or how quickly in progresses.
The first pt was preeclamptic, went into HELLP syndrome, had blood and platelet transfusions, emergent c/s and was thought to have cardiomyopathy based mostly on cardiac arrythmias. That diagnosis was confirmed after she was transferred to a tertiary facility. This woman had the benefit of having major risk factors, and being sick enough to require intensive care and cardiac monitoring, and her disease progressed quickly enough for us to see it clearly. We also were "looking" for complications.
My other patient had a spontaneous vaginal delivery after arriving to our unit with limited prenatal care in another state. Her hgb was only 9 on admission and she bled a bit heavy afterwards, received extra fluids and her hgb on discharge was 7. She wanted to go home in under 24 hours, but the doc refused because of her low hgb. She really didn't complain much, but was having dyspnea with exertion and was really tired. She smoked about 1 1/2 ppd and she had some occasional wheezing/rales when her lungs were auscultated.
I remember documenting this, and informing the doc, who of course told me, "Well, what do you expect from someone who doesn't take her vitamins, looses blood and smokes almost 2 ppd?" All of which is true, which is why her diagnosis didn't occur for about 3 weeks, when she showed up in the docs office for her pp visit with increased edema, weakness and extreme dyspnea.
The biggest problem with teaching on discharge and diagnosis is that many of the sx are similar to normal pp findings. With the exception of extreme dyspnea/orthotic dyspnea, hemoptysis and chest pain the other sx can often be attributed to other causes. Many women don't have ALL the sx, or they have other more common problems that may hide the diagnosis (caring for a new baby/blood loss/low hgb=fatigue and dyspnea).
One of my nursing instructors always said, "It's always better to look for hay in a haystack, but keep in mind that sometimes there IS a needle." Luckily, most of the time it really is the "hay" causing the problem. I always keep cardiomyopathy in the back of my head. Discharge teaching includes SOB, chest pain and unexplained abd. pain as "Call doc/911 right away" sx, but apart from that we don't have specific info on cardiomyopathy.