Are you addressing the OP from November 2020, for whom a couple of us had legitimate concerns, or @Viso, who posted today at noon and seems to be well on the way to recovery? Either way, blanket advice to achieve the level of cardiovascular fitness you're describing prior to diving, especially in the setting of cardiac anomalies, is neither prudent nor realistic. Cardiac fitness to dive is an individual conversation between the prospective diver, the cardiologist, and if deemed necessary, a physician trained and experienced in evaluating divers.The replies you have gotten are from some very learned folks. That said, please remember the highest diving deaths per age group is 50-59 and the second highest 60-69 with fewer from 70-79 because few 70-79 year olds dive. Next, the second highest cause of diving deaths, after drowning, is cardiac arrest. Many of those drownings are cardiac related. So, what I will say will offend you but just because you can climb one mountain on a certain day doesn't mean you won't eat a **it sandwich and die the first time you dive because of cardiac arrest. What is your resting heart rate? What is your max heart rate? Have you had a stress test in the last six months? What is your BMI? Can you run 3 miles without stopping? I'm 55 and run 5 miles a day or bike 20 at least 5 days a week and have a resting heart rate in the 40s and diving can be tough. I road a 145 mile bike race six weeks ago and if I hadn't separated my shoulder in a 24 mph bike crash would have run a 1/2 marathon and done three other long bike races already this summer. If you're not in shape and especially if you've had heart problems don't dive. Just don't. It's not worth it. In Key Largo in March I had a dive instructor telling me how many 50 somes they'd seen die at the end of a dive trying to get back in the boat. I see way to many people diving that shouldn't be because they are overweight and out of shape let alone have heart problems. Call us back when you are running 5 miles a day 5 days a week, had a stress test, and are cleared by your cardiologist to dive.
You mentioned the 13 mets / 7 1/2 minute criteria in another post, though from that post it seems like you're saying that 7 1/2 minutes of jogging will achieve 13 mets, which is not necessarily the case, e.g. at your professed level of fitness, you would not be at 13 mets after 7 1/2 minutes of jogging. Bove's original recommendation was to achieve 13 mets and sustain it for 7 1/2 minutes. Nuanced, but different. At any rate, this is not aligned with current recommendations for average recreational diving (sustained activity at 6 mets), though you'll still see it cited from time to time.
Best regards,
DDM