@texan1 I see that this is your first post! Welcome and I am glad you shared your experience. I have never been on Camzyos (had a septal myectomy) but do read the many unique experiences posted by participants. Every contribution is helpful to those on Camzyos. I would bet that the Texas heat (and humidity in the eastern part of the state) is bothersome to most no matter what their medical status may be. I found this article issued by the UK government that addresses your experience - the dizziness and passing out (syncope) are mentioned. https://www.gov.uk/government/news/dont-let-the-heatwave-affect-your-medicines-three-important-tips-from-the-mhra.
Please share your coping strategy for when you must be outdoors during hot weather.