MI patient with LVEF 25% Detectors?

My father is 57 years old. He had MI in 2010 and underwent angioplasty. At that time his LVEF was 30%, now it has come down to 25%. I am concerned as to why this happened and is there a way to increase or prevent it from further deteriorating. He has on the medication of ACE inhibitors, Beta blocker, statins and ecosprin (I can share the prescription details if helps). He has been advised by his cardiologist to get ICD done. We would like to get a second opinion on what should be our next steps and should we go ahead with ICD? Are there any risks associated with ICD? The ICD device that cardiologist has recommended is MRI compatible. Would there be any life style modification required post that? Would there be restriction in crossing metal detectors?