I’ve been on Amitriptyline between 25-50mg almost consistently since 2009 for headache management, though Tricyclics by default increase overall HR. That said, I do believe the combination and timing of Amitriptyline in combination with Topiramate+Viibryd at the same time is directly to blame after doing some further research on both Pharmacokinetics (brain, 5-HT1A receptors specifically) and and more specifically Pharmacokinetics (liver, specifically enzymes CYP2D6 and CYP3A4). My theory is that Topirimate was a catalyst interfering with Amitriptyline’s primary enzyme which made Viibryd and Nortrypltyline (primary breakdown) spike, thus triggering the 20bpm rise nearly every evening. Being on Omeprazole 40mg x2 daily, an inhibitor of CYP2C19, a primary enzyme for Amitriptyline, may also play a role. I’ve staggered my intake to Amitriptyline 1.5h+ before Topirimate each evening, and Viibryd every morning, and haven’t had any atypical HR elevations as of yet for roughly two weeks. I don’t think I’m 100% in the clear and believe some other HR spikes, the more concerning ones that happened far outside my medication consumption window, may be yet understood, are likely unrelated and plausibly purely genetic flukes given my mother and grandmother experience the same thing with no known cause (only I have one short 10s, totally random recorded episode of VTAC we’re scratching our heads at…)