AITA for saying I'd rather my niece die than get a "big surgery" to potentially save her?

This topic is sensitive to say the least, and names have been changed.<br><br>My sister (31F) has one daughter (9F, hereafter referred to as E). E was diagnosed with "a heart condition" (I'm not sure what specifically, and I don't know if the details even matter, but it is not genetic or caused by poor health). My family knows enough to understand that E's condition has been getting worse over time, due in large part (if not entirely) to the fact that she "has to wait until she gets bigger" before the surgery can happen. E was diagnosed at age 6.<br><br>E has been having more serious complications lately, including what sounded like a near heart-attack to me (racing heart, pain, etc.), and has been hospitalized twice since November. The second hospitalization is what prompted my sister to message me (and presumably other family) with a long story that essentially ended with "the doctor says she might need the surgery sooner rather than later, but we won't know until we talk to her cardiologist in a few days." The story ended by saying that both of my sister's children would be staying with her ex-husband for "a few days" until she heard back from the cardiologist.<br><br>At this point I said, "Why are they waiting a few DAYS to talk to the cardiologist?????" I looked up the name of the hospital, and they have several cardiologists on staff, specifically for children, who would be able to do the surgery. I told my sister this, and she insisted that she can't just choose a random cardiologist and random surgeon because they "need to find the right one". I reminded her that E has already had TWO cardiologists in addition to her primary care doctor who are all in communication with each other, and that she has already been accepted by a surgeon who will do the surgery when E is "big enough". I pointed out that there are actual risks to E staying in the hospital for even a few days (hallway patient and COVID come to mind), and that she might be able to get into a room sooner if they put her on the surgery list. I finished by saying "I would sooner do the big surgery on a small girl than have my daughter die in front of me in the hallway"<br><br>My sister called me an asshole for saying that. I don't. I just... I don't get it. The kid already needs the surgery! It's already affecting her. There are cardiologists and a surgeon already assigned to this case! Why wait? I think she might be doing this to save face, because her ex-husband originally pushed VERY hard for her to have a different cardiologist, and she refused saying "I just want the same cardiologist E has always had because I trust them and they know her". I'm sure it would be embarrassing to admit that maybe he was right and she should have listened to him. I just don't get it. Am I the asshole here?