BOSTON—Medications like beta blockers (BB) and calcium channel blockers can be safely used in an outpatient setting and significantly reduce the intravenous (IV) BB to slow heart rate on the day of CT angiography (CTA), according to a poster presentation at the American Society of Nuclear Cardiology (ASNC) conference on Sept. 12.
Depending on the practitioner’s comfort, BB administration is done either exclusively by the aggressive rapid IV administration while on the table (IV metoprolol 5 mg every minute up to a maximum dose of 50 mg) or by the conservative oral outpatient three-day preparation with metoprolol (Lopressor, Novartis Pharmaceuticals) or atenolol (Tenormin, AstraZeneca), according to the study’s background information.
According to the researchers, concerns regarding patient safety have resulted in some practices considering the purchase of more expensive scanners with increased temporal resolution to eliminate the use of such rate slowing medications during CTA.
D. Gopalakrishnan, MD, from the Heart Hospital Baylor Plano in Texas, and colleagues studied 51 consecutive patients (age 56, 71 percent males) with an intermediate likelihood of coronary artery disease, who underwent CTA. They initially assessed the heart rate three days before the procedure and the patients were started on BB, either metoprolol or atenolol once a day.
On the day of testing, the authors wrote that they measured the heart rate again and if the heart rate was higher than 65, IV metoprolol was used, up to 10 mg also was used to assist the BB.
According to the investigators, 71 percent of the individuals received a daily outpatient BB based on the initial heart rate assessment, 29 percent required IV BB on the day of CTA and only one required additional IV verapamil (Securon, Abbott).
Receiving outpatient BB reduced the use of IV BB on the day of CTA to slow the heart rate by 69 percent, according to researchers. In those who already received outpatient BB, only 31 percent required IV medications to further assist versus 27 percent with optimal initial heart rate who did not receive prior oral BB. They found that the heart rate at time of acquisition was 59.7 bpm.
Gopalakrishnan and colleagues found that the images acquired with a 64-slice scanner “were of good quality without significant motion artifacts.” They found that there were no adverse events while the patients were in the lab or after going home, and the medications were well tolerated.
During CTA, the authors wrote that contrast-related reactions are more likely to happen than those caused by such heart rate slowing medications.