Call your doctor soon, and ask when getting an auto cpap and/or the second sleep study (cpap titration study) can be arranged.
Depending on where you live, it can take time to schedule the second sleep study. So I would press them to order you an auto cpap as soon as possible, at least until they do the overnight titration sleep study. You have heart issues, so I think that is urgent enough of an excuse for them to set you up with an auto cpap soon, to start treating you.
If I read your numbers right, your AHI was 21.8. That means you had nearly 22 apneas and hypopneas per hour during your sleep. So it is like stopping breathing nearly 22 times an hour, if you can imagine that. As a result, your blood oxygen levels are reduced, which is typical of sleep apnea. There's more that can be said about the numbers, but the important thing is you ought to call your doctor tomorrow and arrange something, preferably the auto cpap, which was one of the options mentioned. The auto cpap adjusts the pressure according to what is needed at any given time during your sleep.
Moderate sleep apnea seems right. But it's all relative. Sleep apnea is sleep apnea, whether mild, moderate or severe. And it can get worse if left untreated. Generally speaking, mild apnea is an AHI of 5-15; moderate is 15-30; severe is 30 or more.
I know you are confused and probably overwhelmed by this. But call tomorrow if you can, ask when you can get an auto cpap (or the titration study). Remind them that you are having heart issues, so they might hurry things up for you. As you might know, untreated sleep apnea creates heart problems. So treatment is needed.
Let us know how things go.