• Carlos Eduardo Rochitte, Guilherme Santana Antunes Azevedo, Afonso Akio Shiozaki, Clerio Francisco Azevedo, and Roberto Kalil Filho.
• Instituto do Coração, HCFMUSP, São Paulo, SP, Brazil. rochitte@incor.usp.br
• Arq. Bras. Cardiol. 2012 Aug 1;99(2):706-13.

BackgroundReducing heart rate (HR) in CT angiography of the coronary arteries (CTACor) is critical to image quality. The effectiveness of calcium channel blockers as alternatives for patients with contraindications to beta-blockers has not been established.ObjectivesTo compare the efficacy in the reduction of HR and RR variability of metoprolol and diltiazem in CTACor.MethodsProspective, randomized, open study that included patients with clinical indication of CTACor in sinus rhythm with HR > 70 bpm and no use of agents that could interfere with HR. Fifty patients were randomized to the groups: metoprolol IV 5-15 mg or up to HR ≤ 60 bpm (M), and diltiazem IV 0.25 to 0.60 mg/kg or up to HR ≤ 60 bpm (D). Blood pressure (BP) and HR were measured at baseline, 1 minute, 3 minutes and 5 minutes after the agents, at the acquisition and after CTACor.ResultsHR reduction in absolute values was higher in group M than in group D (1, 3, 5 min, acquisition and post-test). The percentage reduction of HR was significantly higher in group M only 1 min and 3 min after the start of the agents. There was no difference in 5 min at acquisition and after examination. The percentage RR variability in group D was lower than that in group M during acquisition (RR variability/mean HR of acquisition). A single case of AVB, 2:1 Mobitz I occurred, which was spontaneously reverted (group D).ConclusionWe conclude that diltiazem is an effective and safe alternative to beta-blockers in the reduction of HR when performing computed tomography angiography of coronary arteries.

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