P175 PARADOXICAL RESPONSE DURING DOBUTAMINE STRESS ECHOCARDIOGRAPHY: A CASE REPORT

Abstract

Abstract Background Dobutamine Stress Echo (DSE) is a test widely used in the diagnosis of ischemic heart disease. The purpose of the following work is to describe a clinical case with uncommon behaviour. Case Description: 63–year–old female with dyspnoea on mild exertion, and history of NSTEMI–ACS 5 years prior with Coronary Angiography (CA) finding of 3–vessel coronary artery disease, treated with PCI + stent (DES) of right coronary artery (CDX), untreated disease sub–occlusion of the first marginal obtuse (OM1), and chronic occlusion of the anterior interventricular artery (IVA). We decide for DSE. During 20 mcg/kg/min infusion, the patient reported dyspnoea and paradoxical bradycardia (BP) was documented on the ECG, in the absence of ST changes, with the appearance of akinesia of the basal and mid posterolateral segments and worsening of the inferior hypokinesia, present in basal conditions on Echocardiograms (EC). The BP and the alterations of the ventricular motion (VCA) did not respond to the administration of Atropine (1+1 mg) while the administration of 240 mg of Aminophylline (AM) restored the HR and the VCA to baseline values. The CA demonstrated patency of the CDX with the presence of collateral circulation for IVA and occluded OM1. Discussion This case is characterized by the presence of a double paradox: the BP and the Atropine–Resistance (AR). BP during DEB, as demonstrated in previous studies, occurred in 8% of cases, with signs of significant coronary artery disease in 57% of cases. The BP is an expression of ischemia only in just over half of the patients, in the rest of the cases it appeared referable to the Bezold–Jarish reflex, a vagal reflex determined by the stimulation of the intracardiac mechanoreceptors. In our case, the presence of AR seems to exclude the possibility that bradycardia is due to this reflex. The appearance of paradoxical bradycardia during DSE is a rare complication and can lead to premature termination of the test with inconclusive results. In our case, the BP and the AR confirm the positivity of the test also in consideration of the response to the AM antagonist of Adenosine, which accumulates during ischemia. Conclusions This uncommon response to DSE, where AR and AM response in addition to BP could identify patients with severe coronary artery disease in whom the ischemic response is driven by adenosine accumulation, rather than a vagal reflex responding to atropine administration.