You're 70? Brother, unless your "complete cardiac workup" three years ago included coronary angiography you can't really rule out cardiac. You should have at least gotten an EKG. And "pain under my ribs and to the right" is pretty damned protean- as I said, there are a lot of things it could be. Yes, one of them is a hiatus hernia, but worry about that once you have a diagnosis. And, actually, your stomach is a bit to your LEFT though the hiatus is essentially midline. Epigastric/right subcostal pain says gallbladder to me but, y'know, when you're a hammer every problem starts to look like a nail. (I'm certainly not diagnosing you over the interwebs- I'm just trying to point out that you don't have a diagnosis yet. But your doc may well have information that I lack- for instance if you've ever had a CT in the past and so she knew that you already had a small hiatus hernia and just wants to see if it has gotten bigger, etc.)
Now- what if it is a hiatus hernia? Well, as I pointed out, you're 70. If it is asymptomatic and sliding I would propose that you don't need to have it fixed, since something else is likely to get you before esophageal cancer does. Kinda morbid, but that's how you can look at it. Surgery at 70 is itself a bit dangerous, though you do sound healthy from your self-description so you shouldn't outright fear surgery if it comes to that. And even if it is symptomatic- by which I mean it causes reflux- the modern medications for that are DAMNED effective, and they have almost put us surgeons out of the fundoplication business. (Fundoplications are the surgery done for reflux, but are also how we fix HH with the addition of closing the hernia defect somehow- nowadays I prefer biologic mesh.) If you don't have surgery you'd still need surveillance every so often with a scope like the one they have planned for you, since there is some concern that bile reflux can cause problems even without the presence of acid. The only thing that actually no-kidding requires surgery is if they find certain changes in your esophageal lining cells that indicate that they are already changing towards being cancerous, or if the hernia is paraesophageal. (But even that last is a bit contentious- there are studies that show that the risk is probably quite low per annum, so in a 70 year old that risk might be tolerable. OTOH in a 70 year old stomach strangulation is almost certainly fatal in the unlikely event that it does happen.)
If it is any indication, I'm a surgeon and I would take the meds over a Nissen fundoplication if there was any way that I could. That said, it's a good surgery- I just see no reason to take even the small risk involved given that the meds are so effective. I'd certainly find a guy who has done hundreds of them, too, if I needed surgery, because as I said most non-laparoscopic-specialist surgeons don't do a lot of them anymore. I only do maybe a dozen a year. They are fun, though...
Are you still having pain? I ask because pain is an uncommon complaint with HH. Usually the chief complaint is reflux.