Hello,
The initial post above should be taken as a good primer, but in no way should it supplant the information given to you by your physician, as HTN management is far more complex and is often tailored to the individual patient (as a practicing physician myself)
With HOCM, minimizing sodium intake can help, but the main issue is the outflow tract obstruction which occurs due to increased intraventricular septal mass. The drug of choice, or rather the therapeutic effect of choice with this particular condition is a reduction of heart rate, not necessarily effective circulating volume. With a reduced heart rate, which is often achieved with Beta Blockers like metoprolol, there is increased ventricular filling time, and an improved cardiac output. With fast heart rates (often HR above 90) there is an effective outflow tract obstruction due to the asymmetric interventricular septum which causes decreased cardiac output and an unsafe drop in blood pressure.