Identification of viable myocardium early after acute myocardial infarction under beta-blockade by enoximone echocardiography

• Published in: Giornale italiano di cardiologia Vol. 27; no. 4; p. 342
• Main Authors: Natale, E, Minardi, G, Wang, F, Tubaro, M, Giovannini, E, Vajola, S F, Milazzotto, F
• Format: Journal Article
• Language: English
• Published: Italy 01.04.1997
• Subjects: Acute Disease; Adrenergic beta-Agonists - adverse effects; Adrenergic beta-Agonists - pharmacology; Adrenergic beta-Antagonists - adverse effects; Adrenergic beta-Antagonists - pharmacology; Cardiotonic Agents - adverse effects; Cardiotonic Agents - pharmacology; Dobutamine - adverse effects; Dobutamine - pharmacology; Echocardiography - drug effects; Enoximone - adverse effects; Enoximone - pharmacology; Female; Follow-Up Studies; Hemodynamics - drug effects; Humans; Infusions, Intravenous; Male; Metoprolol - adverse effects; Metoprolol - pharmacology; Middle Aged; Myocardial Contraction - drug effects; Myocardial Infarction - pathology; Myocardium - pathology
• ISSN: 0046-5968

The influence of the beta-blocker metoprolol on the capacity either of low-dose dobutamine echocardiography or the recently introduced enoximone echocardiography to detect viable dysfunctioning myocardium after myocardial infarction was investigated. Initial clinical experience would suggest that the phosphodiesterase III inhibitor enoximona could be an alternative pharmacological stimulation, inducing an increase in contractility in the presence or absence of beta-receptor stimulation. Ten patients with a baseline low-dose dobutamine-echocardiographic test (up to 10 micrograms/kg/min) positive for myocardial viability in > or = 1 segment(s), performed 4-5 days after a first acute myocardial infarction treated with rtPA, were randomized after the administration of intravenous metoprolol (15 mg in three 5-mg boluses) either to dobutamine (up to 15 micrograms/kg/min) or to an enoximone intravenous bolus (1 mg/kg over 5 min) under echocardiographic monitoring, in a crossover sequence, with a 24-h interval. The infarct related artery was patent (TIMI grade 2 o 3) in all the patients. Follow-up echocardiograms were performed 5-7 weeks later. Resting asynergy was found in 40 segments; of these, 17 were viable. All the viable segments remained unresponsive during the post-metoprolol dobutamine infusion, while improved their contractility during enoximone echocardiography. Two patients suffering from early post-infarction angina underwent coronary angioplasty successfully. Eight out of ten patients (2 revascularized and 6 not) showed contractile recovery in a total of 14 segments at the follow-up echocardiogram. Sensitivity, specificity and overall accuracy in predicting reversible dysfunction after acute myocardial infarction for enoximone echocardiography were 93, 85, and 88%, respectively. Our results support the value of enoximone echocardiography in the identification of myocardial viability after myocardial infarction, in patients treated with beta-blockers, which interfere heavily with the results of dobutamine echocardiography.