Question: What are the benefits and side effects of Beta blockers?
Answer: There are a lot of benefits of ACE inhibitors, or beta blocker therapy, very much like ACE inhibitors as we discussed. They also lower blood pressure in patients who have high blood pressure. In patients who have had a heart attack, beta blocker reduces the risk of recurrent heart attacks.
But as we discussed, probably the most potent effect of beta blockers are in patients with heart failure where there is a dramatic -- about 35 percent -- reduction in all-cause mortality, risk in certain cardiac death, and improve symptoms and risk of hospitalization.
So I think all in all the benefits are fairly numerous, however beta blockers do have a lot of side effects. Now the problem is that a lot of side effects of beta blocker therapy are similar to the symptoms of heart failure in itself. So for example, beta blockers have been associated with weakness, with fatigue, with tiredness, and with shortness of breath. And these are the symptoms of heart failure, so I think in real life it becomes very difficult to find out whether it is related to the medication or the patient's disease, especially once you've educated the patient and told them that you might actually have these side effects and then you wonder whether the patients look for those side effects.
Well, where do you get the answer to that question? You get the answer to that question by looking at clinical trials which were blinded and nobody knew whether that patient was getting placebo or beta blockers. And invariably in every clinical trial we find out that the discontinuation rate due to side effects was higher in the placebo arm rather than the beta blocker arm. In other words, a lot of times it's not the beta blockers but the disease itself and stopping the therapy may not be in patient's benefit.
So I think one has to be careful, you know if the blood pressure's excessively lowered and the patients have dizziness, one can give lower doses or cut back on some of the medications like nitrates or diuretics that do not improve mortality in these patients. So maybe we can balance that out.
In patients with peripheral vascular disease that can cause claudication, in patients with other forms of peripheral vascular disease for instance it may worsen the risk of erectile dysfunction for instance. But remember, even lower doses of beta blockers are considerably better than no doses of beta blockers so we always try to achieve higher doses but if patients are having a lot of dose dependent side effects -- even getting by with smaller doses of beta blockers it is a whole lot better than stopping beta blockers completely.
Again some patients who have asthma and not necessarily emphysema, but bronchospastic asthma where patients are wheezing, beta blockers may worsen the risk of wheezing and should be used relatively carefully.
It may also worsen glucose tolerance and worsen diabetes control or increase the risk of new onset diabetes, but remember that not all beta blockers are the same, and most of these side effects like claudication, worsening erectile dysfunction, glucose intolerance, are more related to beta 1 selective drug and other non-selective beta blockers like carvedilol you may not have as much for example glucose intolerance.
So my general consensus would be that the benefits are so numerous that one should either try to cut back and at least give lower doses of beta blocker and not stop them all together, or switch to a non-selective beta blocker or use a non-selective blocker preferentially to see if the side effects are less. But I also want to emphasize that if you look at the large registries, a good 80 to 90 percent of patients are able to tolerate at least some doses of beta blockers and therefore we ought to at least try our best before giving up on them.