One of the difficulties is that the heart is both healing and changing during this time, adapting to a much easier existence, remodelling to a less massive muscle, rejoining endothelium at the surgical points, regrowing tiny neural path attachments severed in the surgery.
Blood pressure, pulse rates, and other heart issues (such as occurrences and types of arrhythmias) can rise and fall rapidly during the first year, particularly for the first three to six months.
Because of this, it's difficult to choose the correct path to take in regard to them. Your cardiologist certainly should know about these types of changes, but none of these changes should be considered at all permanent. A large number of people report post-sugical changes to pulse rates and blood pressure, and particularly report that these changes evolve as they continue to heal. This is fine when they're headed in a direction we like, but disappointing or threatening when they are negative in nature. We mostly hear about them here when that's the case. However, the pendulum does tend to continue swinging, and many of these unhappy results do turn around as a matter of time and course. Each person is different, as is each result.
My personal bias is that this should be a strong consideration for medications prescribed to treat these often temporary - sometimes fleeting - conditions. Wherever reasonably possible, a flexible approach to the initiation, potency, and the longevity of presciptions would likely best serve the postoperative patient. The heart has been exposed to some trauma, and will take some time to reregulate itself. The desire to keep HR or BP symptoms from going too far out of control needs to be balanced with the understanding that the body may be trying to work out those issues on its own at the same time.
It's particularly important to keep an eye on blood pressure and pulse, as they often do vary from month to month in the initial healing year (even longer for some). The medication given to halt a dramatic rise the month before may be causing faintness (syncope) five weeks later from low pressure. Beta blockers slow the heart rate to aid in healing and lessen pressures on the new valve, but changing circumstance can make them overly aggressive. Not everyone is able to function well at a 50 BPM rate.
Also, as blood pressure medications tend to lose effectiveness over time, it's important not to overuse them, particularly in younger people. If a BP medication isn't helping, the patient should try to get off of it as rapidly as the physician and the medication's profile allow. If the patient's blood pressure is managed down to the very low end of the normal spectrum, instead of congratulating the fact that it's solidly under control, ask the prescriber to consider whether the dosage could be lowered and still leave the patient within the theraputic range.
If your home equipment is regularly measuring a lower pressure than is measured in the doctor's office, ensure that you're using the measuring unit properly. If you are, the chances are that the doctor's measurements are atypical, caused by situational stress ("white coat syndrome"). Rather than allowing prescriptions to be made purely on the basis of BP readings taken in the office, ask for an ambulatoiry blood pressure monitor for overnight measurement.
It's surprising how many times the practical (typical) blood pressure is actually found to be lower than the physician's readings. Imagine how many blood pressure prescriptions are based on a single, correctly performed, but misleading measurement done in a doctor's office.
Best wishes,