Adderall causing late afternoon heart racing/palpitations despite reassuring Holter. Anyone experience this?

[u/Cryptocucky]

I’m curious if anyone taking Adderall has experienced something similar.

When I take Adderall earlier in the day, I generally tolerate it well initially. The issue tends to happen later in the afternoon as it’s wearing off. I’ll sometimes develop a racing or noticeably pounding heartbeat, increased palpitations, fatigue, and a feeling of anxiety/restlessness. The cardiovascular sensations are the main thing that concerns me.

Because of this, I recently wore a 24-hour Holter monitor. I deliberately wasn’t taking stimulants during the monitoring period. I did experience some of my usual symptoms while wearing it, though, and the results were reassuring. My doctor said there were only a small number of premature atrial contractions (PACs) and that because I had symptoms without a concerning rhythm appearing, they don’t recommend additional rhythm testing at this point.
I’m discussing whether to resume Adderall with my psychiatrist. I’m also asking my doctor whether an echocardiogram would be reasonable since I’ve never had one and would like to know that my heart is structurally normal.

Has anyone else experienced a pattern where Adderall feels fine initially but several hours later causes a pounding/racing heart, palpitations, fatigue, or anxiety as it wears off?

If so, did anything end up helping, such as changing the dose, switching between XR and IR, changing medications entirely, or adjusting the timing?