IV beta blockers before angioplasty are safe, but offer no clinical benefit

April 03, 2016

Giving intravenous beta blockers before performing a coronary angioplasty in patients who had experienced the deadliest form of heart attack--ST-segment elevation myocardial infarction (STEMI)--was safe but did not reduce heart attack severity or improve blood flow from the heart's main pumping chamber, according to research presented at the American College of Cardiology's 65th Annual Scientific Session.

"In patients with STEMI, beta blockers have been shown to improve survival, reduce the risk of another heart attack, reduce life-threatening arrhythmias and prevent enlargement of the heart," said Vincent Roolvink, M.D., of Isala Klinieken in Zwolle, Netherlands, and lead author of the study. "This was the first large, double-blind, randomized, placebo-controlled trial to assess whether giving intravenous beta blockers before these patients undergo angioplasty would further improve their outcomes. Unfortunately, we showed that it did not."

STEMI is a severe form of heart attack caused by prolonged blockage of blood supply in the heart. It requires immediate angioplasty, a non-surgical procedure in which a balloon is fed into the blood vessels through a catheter and inflated to open narrowed or blocked arteries, allowing blood to flow. A stent is often placed at the blockage site to keep the artery open. In the United States, about 250,000 people experience a STEMI every year.

Results from two previous trials had suggested that giving intravenous beta blockers to STEMI patients before they underwent angioplasty could reduce heart attack severity or improve blood flow from the left ventricle, the heart's main pumping chamber, but these trials had shortcomings, Roolvink said. One had a small enrollment and the other, while larger, was not blinded or placebo-controlled and enrolled only patients whose STEMIs involved the front wall of the left ventricle.

In the EARLY-BAMI (Effect of Early Beta-blocker Administration before primary PCI in patients with ST-elevation Myocardial Infarction) trial, which was conducted in the Netherlands and Spain, 683 patients (average age 62, 75 percent male) with acute STEMI symptoms of less than 12 hours duration were randomly assigned to receive the beta blocker metoprolol or a placebo before undergoing angioplasty. The primary endpoint was the severity of the heart attack as measured by magnetic resonance imaging (MRI) at 30 days. Secondary endpoints were levels of cardiac enzymes and number of occurrences of ventricular arrhythmia. Safety endpoints were symptoms of an abnormally slow heart rate, symptoms of abnormally low blood pressure and cardiogenic shock (sudden inability of the heart to pump enough blood to meet the body's needs).

At 30 days of follow up, the primary endpoint of average heart attack severity measured by MRI was 15.3 percent of left ventricular volume on average in the beta blockers group, compared with 14.9 percent in the placebo group, a difference that was not statistically significant, Roolvink said. Nor were there significant differences between the two groups on blood flow from the left ventricle or levels of cardiac enzymes (secondary endpoints). Ventricular arrhythmias occurred in 3.6 percent of patients who received beta blockers and in 6.9 percent of those who received a placebo, a difference that met the threshold for statistical significance but did not result in a clinically significant difference, Roolvink said. Sixteen patients in the beta blockers group experienced symptoms of an abnormally slow heart rate, symptoms of abnormally low blood pressure, or cardiogenic shock, compared with 21 patients in the placebo group, a difference that again was not statistically significant.

A limitation of the study is that overall heart attack severity among enrolled patients was lower than expected, which could explain why beta blocker treatment appeared to offer no benefit, Roolvink said. Also, although MRI analyses for the primary endpoint were blinded for both heart rate and study medication, it was not possible to blind physicians and nurses to patients' heart rate and blood pressure.

Going forward, researchers said additional large randomized trials are needed to clarify whether intravenous beta blocker treatment before angioplasty offers any benefit for STEMI patients.
-end-
The Early-BAMI trial was funded by the Dutch Heart Foundation and by an unrestricted grant from Medtronic, Inc.

The study was published in the Journal of the American College of Cardiology simultaneously with its presentation at the scientific session.

The ACC's Annual Scientific Session, which in 2016 will be April 2-4 in Chicago, brings together cardiologists and cardiovascular specialists from around the world to share the newest discoveries in treatment and prevention. Follow @ACCMediaCenter and #ACC16 for the latest news from the meeting.

The American College of Cardiology is a 52,000-member medical society that is the professional home for the entire cardiovascular care team. The mission of the College is to transform cardiovascular care and to improve heart health. The ACC leads in the formation of health policy, standards and guidelines. The College operates national registries to measure and improve care, offers cardiovascular accreditation to hospitals and institutions, provides professional medical education, disseminates cardiovascular research and bestows credentials upon cardiovascular specialists who meet stringent qualifications.

Roolvink will be available to the media in a press conference on Sunday, April 3, 2016, at 12:15 p.m. CT/1:15 p.m. ET/5:15 p.m. UTC in Room N229.

Roolvink will present the study, "Effect Of Early Administration Of Intravenous Beta Blockers In Patients With ST-Elevation Myocardial Infarction Before Primary Percutaneous Coronary Intervention. The Early-BAMI Trial" on Sunday, April 3, 2016, at 10:45 a.m. CT/11:45 a.m. ET/3:45 p.m. UTC in the Main Tent (North Hall B1).

American College of Cardiology

Related Blood Pressure Articles from Brightsurf:

Children who take steroids at increased risk for diabetes, high blood pressure, blood clots
Children who take oral steroids to treat asthma or autoimmune diseases have an increased risk of diabetes, high blood pressure, and blood clots, according to Rutgers researchers.

High blood pressure treatment linked to less risk for drop in blood pressure upon standing
Treatment to lower blood pressure did not increase and may decrease the risk of extreme drops in blood pressure upon standing from a sitting position.

Changes in blood pressure control over 2 decades among US adults with high blood pressure
National survey data were used to examine how blood pressure control changed overall among U.S. adults with high blood pressure between 1999-2000 and 2017-2018 and by age, race, insurance type and access to health care.

Transient increase in blood pressure promotes some blood vessel growth
Blood vessels are the body's transportation system, carrying oxygen and nutrients to cells and whisking away waste.

Effect of reducing blood pressure medications on blood pressure control in older adults
Whether the amount of blood pressure medications taken by older adults could be reduced safely and without a significant change in short-term blood pressure control was the objective of this randomized clinical trial that included 534 adults 80 and older.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Here's something that will raise your blood pressure
The apelin receptor (APJ) has been presumed to play an important role in the contraction of blood vessels involved in blood pressure regulation.

New strategy for treating high blood pressure
The key to treating blood pressure might lie in people who are 'resistant' to developing high blood pressure even when they eat high salt diets, shows new research published today in Experimental Physiology.

Arm cuff blood pressure measurements may fall short for predicting heart disease risk in some people with resistant high blood pressure
A measurement of central blood pressure in people with difficult-to-treat high blood pressure could help reduce risk of heart disease better than traditional arm cuff readings for some patients, according to preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.

Heating pads may lower blood pressure in people with high blood pressure when lying down
In people with supine hypertension due to autonomic failure, a condition that increases blood pressure when lying down, overnight heat therapy significantly decreased systolic blood pressure compared to a placebo.

Read More: Blood Pressure News and Blood Pressure Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.