EF at 25%, your wife may need more assistance like an implantable cardiac debrillator (ICD). This can be a life saving situation for your wife.
Dilated cardiomyopathy can be due to a heavier than normal workload. A dilated left ventricle can reduce the EF (fraction of blood pumped with each heartbeat...normal is 50 to 70%).
Coreg is good medication that helps stabilize heartrate and help reduce the heart's workload. Dig is medication to increase the heart's pumping contractions.
A cath is usually done to determine if there are any coronary artery occlusions. If there are occlusions the heart works harder to pump against higher resistance. Based on what you have stated in your post doesn't indicate any coronary artery disease (plaque buildup in the vessels). I wouldn't consider it as a standard. Usually the last procedure when there is evidence of coronary artery disease. An EKG can be positive for the condition, but it isn't a very reliable source.
I can't answer the question if it is advisable or appropriate to delay an ICD or PM until there is a definitive stability and increase in the EF. The doctor would be the best source for an answer.
I had ischemic congested heart failure 7 years ago. My heart was enlarged and an EF below 29%. My medication is coreg (keeps heart rate under control), and ACE inhibitor to reduce blood pressure. That may be continued if there is high blood pressure and a need to control heart rate. It was never a consideration to implant a pacemaker or ICD.
I hope this helps, and if you have any further questions you are welcome to respond. Take care.