Heart Rate and Beta Blocker Studies That May Impact Those with Atrial Fibrillation
October 24, 2008 7:55 AM CT
Recently there have been a number of new beta-blocker and heart rate studies, some of which are contradictory. Here’s a discussion of three recent studies that may apply to those with afib.
1) Heart rates over 70 beats per minute predict heart attack risk
The BEAUTIFUL study, presented recently at the European Society of Cardiology, indicated that heart rate is a powerful predictor of heart attack risk.
They found that those with heart rates over 70 beats per minute (bpm) who have existing coronary artery disease or heart failure are more likely to suffer a heart attack or die from heart disease. There was a 56% increased risk of developing heart failure, a 46% increase in risk of heart attack, and the risk of needing another stent or bypass increased by a third.
The study found that ivabradine—used to treat angina and for those intolerant to beta blockers—lowered heart rates and reduced the incidence of heart attacks, both fatal and non-fatal. There was no effect on hospitalizations for heart failure.
A separate study found that for every 5 bpm increase in heart rate, there is an 8% increase in cardiovascular death, 16% increase in hospital admissions for heart failure, and 7% increase in hospitalization for heart attacks.
While doctors usually pay attention to cholesterol levels and blood pressure, it’s likely that more attention will now be paid to heart rate, though it’s considered too early to incorporate these findings into the practice guidelines.
To read more, see:
2) Slowing the heart rate doesn’t protect those with hypertension—or does it?
While slowing the heart rate is known to prolong life expectancy and to protect those with heart failure or previous heart attacks, a new study found that slowing the heart rate of those with hypertension (high blood pressure) actually shortened life expectancy and caused more heart attacks, strokes, and heart failure.
This study, from St Luke’s Roosevelt Hospital in New York, was just published in the Journal of the American College of Cardiology.
Study authors believe that slowing the heart rate with beta blockers increases the central pressure, which is a determinant of heart attack and stroke.
But other researchers point out that this particular study was done almost exclusively with atenolol, a common beta blocker, and that atenolol is the likely culprit, not slowing of the heart rate.
A hypertension expert was quoted as saying that about 40% of U.S. and U.K. beta blocker prescriptions are for atenolol, but no one should be given atenolol. Part of the problem is that atenolol increases the central aortic pressure, while the new vasodilating beta blockers (carvedilol or nebivolol) do not. He said that hypertension patients with angina need beta blockers, and hypertension patients under age 50 are better treated with beta blockers as well, but that the beta blocker used shouldn’t be atenolol.
So, is it atenolol or lower heart rate that is bad? We don’t yet know, but you can bet there will be studies to sort that out.
Does this apply to other beta blockers? It’s really premature to extrapolate these findings to other beta blockers. So stand by.
But this issue of atenolol vs. the newer vasodilating beta blockers brings up whether central pulse pressure is more important than standard blood pressure readings. One finding is that central pulse pressure is a better predictor of cardiovascular risks than standard blood pressure readings taken on your arm, called standard brachial pulse pressure.
- To learn more, read: Central aortic pressure readings seen as more prognostic than standard brachial pressure
3) The impact of beta-blockers on non-cardiac surgery risks
For those with heart disease, or at risk for it, non-cardiac surgery carries the risk of heart attack, stroke, or even death.
Reports have indicated that there are fewer complications from surgery in those taking beta blockers for hypertension. Thus, researchers investigated whether beta blockers could help.
Patients in Boston undergoing non-cardiac surgery were categorized as to their cardiac risk level. Those who received beta-blockers had lower heart rates during and after surgery, but had higher rates of heart attack (2.94 percent vs. 0.74 percent) and death (2.52 percent vs. 0.25 percent) within 30 days of their surgery.
Those in the beta-blocker group who died had significantly higher heart rates before surgery than those who didn’t (86 bpm vs. 70 bpm). Researchers surmised that a low heart rate before surgery, not just during and following, is essential for the beta-blockers to convey a protective effect.
So perhaps already being on beta blockers for afib has a protective effect for other surgeries. This is certainly worth discussing with your surgeon when you’re deciding which medications to stop prior to surgery.
To learn more, see: