WIKIPEDIA: Blood pressure
There are several reports concerning the effect of CoQ10 on blood pressure in human studies.[22] In a recent meta-analysis of the clinical trials of CoQ10 for hypertension, a research group led by Professor Frank Rosenfeldt (Director, Cardiac Surgical Research Unit, Alfred Hospital, Melbourne, Australia) reviewed all published trials of Coenzyme Q10 for hypertension, and assessed overall efficacy, consistency of therapeutic action, and side-effect incidence. Meta-analysis was performed in 12 clinical trials (362 patients) comprising three randomized controlled trials, one crossover study, and eight open-label studies. The research group concluded that coenzyme Q10 has the potential in hypertensive patients to lower systolic blood pressure by up to 17 mm Hg and diastolic blood pressure by up to 10 mm Hg without significant side-effects.[23]
A friend of mine had a heart attack some time ago and his doctor had him taking co-q10 along with presciption stuff as well. He was told to start loosing weight and exercise. He didn't and just had a second one. I think he got the message this time.