IJCS | Volume 32, Nº5, September/October 2019

DOI: 10.5935/2359-4802.20190003 540 CASE REPORT International Journal of Cardiovascular Sciences. 2019;32(5):540-545 Mailing Address: Maria Gazzilli Via Tresanda del Sale, 1. Postal Code: 25122, Brescia - Italy. E-mail: marinagazzilli@msn.com Left Ventricular Dyssynchrony in a Patient with Normal Perfusion and Stress-Induced Left Bundle Branch Block Maria Gazzilli, 1 R exhep Durmo, 1 C laudio Tinoco Mesquita, 2 Raffaele Giubbini 1 Nuclear Medicine, University of Brescia and Spedali Civili Brescia, 1 Brescia - Italy Hospital Universitário Antônio Pedro, Universidade Federal Fluminense (UFF), 2 Niterói, RJ - Brazil Manuscript received April 08, 2018, revised manuscript May 30, 2018, accepted June 26, 2018. Left Bundle Branch Block, Cardiac-Gated Single -Photon Emission Computer-Assisted Tomography; Myocardial Perfusion Imaging; ContractionMyocardial. Keywords Introduction L e f t bund l e b r a n c h b l o c k ( LBBB ) i s a n electrocardiographic abnormality that occurs in approximately 0.5–1.1% of all patients who undergo exercise testing. 1 The diagnosis of complete LBBB is made with the 12-lead electrocardiogram (ECG) if all the following criteria are met: conduction originating above the atrioventricular node; a QRS duration of 120 milliseconds or more; predominantly upright complexes with broad-slurred R waves in leads I, V5, and V6; and a QS or RS pattern in V1 with a normal intrinsicoid deflection of 35 milliseconds. 2 The precisemechanismand the prognostic significance of Exercise Induced-LBBB (EI-LBBB) remains unclear. EI-LBBB can be associated with coronary artery disease (CAD). However, in a group of patients, coronary arteries are normal. 3 Several authors have attributed EI- LBBB to functional alterations of the conduction system mediated by autonomic influences in non-ischemic cases. 4 We report a case of a 72-year-old female patient who developed LBBB during exercise stress testing and showed reversible abnormalities in cardiac contraction. Case report A 72-year-old female patient, with two risk factors for CAD, namely hypertension and dyslipidemia, underwent a coronary angiography in 2010 after typical chest pain, which showed left anterior descending artery (LAD) stenosis of 80%, right coronary artery (RCA) stenosis of 60% and left circumflex artery (LCX) stenosis of 60%. The patient started medical therapy with ACE inhibitors, β -blocker, antiplatelet agent and statins. In 2014, she underwent a pharmacological (dipyridamole IV, 0.84 mg/kg in 5 minutes) stress-rest myocardial perfusion imaging (MPI) with normal electrocardiogram (ECG) pattern and normal perfusion. In March 2018 the patient came at our attention to undergo MPI as a routine exam. The patient was asymptomatic after 72h-wash out from β -blocker. She was submitted to a bicycle exercise stress testing using the modified Bruce protocol. Baseline heart rate (HR) was 89/min and blood pressure (BP) was 140/95 mmHg. The ECG showed first-degree atrioventricular block and left anterior fascicular block (figure 1A). Technetium- 99m (Tc-99m) tetrofosmin (187 MBq) was injected IV at peak exercise at 4:30 min. HR and BP were 126/min and 180/110mmHg respectively. She developed LBBBwith a QRS width of 120 ms at the end of the 5 th min of exercise test with a HR of 128/min (figure 1B) and no symptoms. The EI-LBBB disappeared at 3:52 min during recovery phase at a HR of 94/min (figure 1C). Stress images were acquired 20 min after radiotracer administration with a Discovery NM/CT 530c CZT gamma camera (GE Healthcare, Haifa, Israel). Rest injection was administered 2 hours after the stress injection and the images were obtained 20 minutes later. Both stress and rest studies were acquired using the list mode using a gated 16 frame-per-cycle acquisitionwith a 20% acceptance window. Acquisition time was 9minutes for the stress and 5 minutes for the rest study. Stress and rest images were reconstructed on a dedicated workstation (Xeleris 4,0 GE Healthcare)