Could zanax and trazadone stop your heart?

Most likely Xanax (alprazolam): Xanax (alprazolam) can slow your breathing down and eventually lead to respiratory arrest which would eventually lead to a heart attack due to lack of oxygen to the cardiac muscle. Trazodone would be less likely to do so, although it could cause serotonergic syndrome in combo w/ other serotonergic antidepressants leading to elevated BP ; heart rate, which, if severe enough could cause the heart to stop.