Análise da contribuição da cintilografia de perfusão miocárdica na decisão entre tratamento clínico vs. revascularização em pacientes com doença coronariana

Um método diagnóstico comumente utilizado por especialistas na detecção da Doença Arterial Coronariana (DAC) é a Cintilografia de Perfusão Miocárdica (CPM). Segundo Lindner et al. (2007), esse método oferece a possibilidade de estabelecimento de indicadores quantitativos que permitem a instituição de estratificações de risco cardíaco. O presente trabalho visou estabelecer um ponto de corte (“cut off”) baseado em um desses índices de estratificação - “SSS%” - capaz de influenciar na decisão terapêutica entre dois tipos de tratamento para DAC disponíveis – clínico (farmacológico) ou invasivo (angioplastia ou revascularização miocárdica). Além disso, este estudo também objetivou fornecer informações clínicas pertinentes que possam auxiliar os profissionais da área na propedêutica para DAC. Foram avaliados, indiretamente, sem acesso a prontuário, a partir de dados registrados em equipamento específico, via código de identificação, 2.529 pacientes. Desse total, foram analisados 129, dentre os quais 39,53% se submeteram ao tratamento clínico e 60,47% se submeteram ao tratamento invasivo para DAC após o resultado do primeiro exame. Houve quantidade importante de pacientes submetidos ao tratamento invasivo que apresentou piora do estado de perfusão cardíaca após a terapêutica e, no geral, os pacientes submetidos ao tratamento clínico apresentaram maior redução dos defeitos perfusionais em relação àqueles submetidos ao tratamento invasivo. Não foi possível determinar o valor “cut off”; entretanto, através das análises com comprovação estatística, concluiu-se que pacientes com grandes defeitos perfusionais cardíacos apresentam resposta positiva ao tratamento invasivo. Pacientes com pequenos defeitos perfusionais apresentam piora quando submetidos ao tratamento invasivo. A diagnostic method commonly used by specialists in the detection of Coronary Artery Disease (CAD) is the Myocardial Perfusion Scintigraphy (MPC). According to Lindner et al. (2007), this method offers the possibility of establishing quantitative indicators that allow the establishment of cardiac risk stratifications. The present study aimed to establish a cut-off point based on one of these stratification indexes - "SSS%" - capable of influencing the therapeutic decision between two types of available treatment for CAD - clinical (pharmacological) or invasive (angioplasty or coronary artery bypass grafting). In addition, this study also aimed to provide pertinent clinical information that may assist practitioners in the propedeutics for CAD. We indirectly evaluated 2,529 patients, without access to medical records, from data recorded in specific equipment via identification code. Of this total, 129 were analyzed, among which 39.53% underwent clinical treatment and 60.47% underwent invasive treatment for CAD after the result of the first exam. There was a significant number of patients undergoing invasive treatment that presented worsening of cardiac perfusion status after therapy and, in general, patients undergoing clinical treatment showed greater reduction of perfusion defects compared to those undergoing invasive treatment. It was not possible to determine the "cut off" value; however, through statistically proven analyses, it was concluded that patients with large cardiac perfusion defects have a positive response to invasive treatment. Patients with small perfusion defects show worsening when undergoing invasive treatment.

Routine clinical use of 15O-water cardiac PET: Initial experience with a novel automated solution

Funding Acknowledgements Type of funding sources: None. Introduction While considered the gold standard for cardiac perfusion imaging and myocardial blood flow quantitation, the use of 15O-water has been largely restricted to research purposes. The practical hurdles associated with the ultra-short half-life of the tracer and the lack of dedicated software have hampered the routine clinical use of 15O-water and novel solutions have been sought to obviate the issues limiting its use. An innovative bedside 15O-water generator designed for simple push button operation and high patient through-put has been developed and recently installed at our institution and utilized clinically under a magistral exception. The system also includes an infusion device and a dedicated display and analysis software. We report the initial experience utilizing such solution for routine clinical use of 15O-water. Methods The first routine human myocardial perfusion imaging tests with PET 15O-water were conducted at our institution in December 2020. The 15O-water was produced and infused using the bed-side water generator. The activity per scan was 400 MBq in 20-35 mL of saline infused at a speed of 1-2 mL/s. Each exam consisted of a low-dose CT followed by a 4 min rest dynamic PET scan and, finally, a 4 min stress dynamic PET scan. Pharmacological stress was induced using a 6 min infusion of adenosine (0.14 mg/kg/min) starting 2 min prior to the stress PET scan. The exam time (time from initiation of the low dose CT to the end of the stress PET scan) was monitored. Images were analyzed using the dedicated software. Results Since its implementation on December 7, 2020 and as of February 23, 2021, all patients referred to the hospital for cardiac perfusion imaging have been studied with this approach. Over this period of time, a total of 295 patients have been imaged with an average of 6 patients per day (a total of 50 scan days, 3-8 patients per day). The median total exam time was 22 min (85% of the exams were within 25 min and 95% below 30 min). Conclusion Routine clinical use of 15O-water PET has been practically implemented utilizing a novel bedside generator and infusion solution. The system has proven to be reliable and efficient. This initial experience suggests that a very high patient throughput is achievable with improved resource utilization. The expected high diagnostic accuracy of the test is being evaluated with the dedicated imaging software.

Prognostic value of hybrid cardiac perfusion SPECT/CT for patients with coronary artery disease after coronary artery bypass grafting

Introduction Patients with coronary artery disease (CAD) undergoing coronary artery bypass grafting (CABG) occasionally experience recurrent myocardial ischemia. Because of their severe CAD and its complicated hemodynamics, conventional cardiac perfusion SPECT often cannot reveal the severity and prognosis solely. Hybrid cardiac SPECT/CT imaging simultaneously shows myocardial ischemia distribution, coronary artery lesion distribution, and their relationship, and this modality may enable detailed interpretation and risk stratification for such patients. Aim This study aimed to assess the prognostic value of hybrid cardiac SPECT/CT for patients with CAD and suspected myocardial ischemia after CABG. Methods A total of 201 consecutive patients, registered between April 2016 and September 2018, with suspected recurrent angina pectoris after CABG requiring examinations for myocardial ischemia were included in this study. Among these, 135 patients who underwent cardiac perfusion SPECT, cardiac CT, and hybrid cardiac SPECT/CT imaging were analyzed. In the SPECT-only analysis, SDS was calculated, and the patients were divided into none-to-mild (SDS <4) and moderate-to-severe ischemia (SDS ≥4) groups. In the SPECT/CT analysis, the patients were divided into a matched group (SPECT reversible accumulation defects [SDS ≥2] along coronary arteries with significant lesions) and an unmatched group (accumulation defects not coincided with coronary artery territories or no significant stenoses in the corresponding coronary arteries). All patients were observed from the time of these tests for the occurrence of major adverse cardiac events (MACE), and the prognostic performances of these analyses were compared. Results In the SPECT-only analysis, 62 were in the none-to-mild group and 73 were in the moderate-to-severe group. In the SPECT/CT analysis, 61 were in the matched group and 74 were in the unmatched group. Within the follow-up period of 29±8 months, 15 patients experienced MACE. The patients' prognoses were clearly stratified by hybrid SPECT/CT analysis (matched: 13/61, 21.3% vs. unmatched: 2/74, 2.7%) compared with SPECT-only analysis (moderate-to-severe: 11/73, 15.0% vs. none-to-mild: 4/62, 6.5%). The hybrid cardiac SPECT/CT analysis was more strongly associated with the occurrence of MACE compared with SPECT-only analysis (p=0.008 vs. p=0.04, respectively). Conclusions Hybrid cardiac SPECT/CT imaging can have higher prognostic value compared with stand-alone cardiac perfusion SPECT for patients with CAD after CABG. Funding Acknowledgement Type of funding source: None

Abstract MP05: Pvn-specific Microgliosis And Inflammation Precedes Sympathoexcitation In gαI 2 Protein-dependent, Salt-sensitive Hypertension

Aim: Hypothalamic paraventricular nucleus (PVN) Gαi 2 proteins mediate sympathoinhibitory responses to a high salt (HS; 4% NaCl) diet. Failure to upregulate Gαi 2 proteins in response to a HS diet results in PVN inflammation and salt sensitive hypertension (SSHTN). We hypothesize that microglial-mediated PVN inflammation precedes sympathoexcitation in Gαi 2 protein-dependent SSHTN. Methods: Three-month-old male Sprague Dawley rats implanted with ICV cannulas fitted to osmotic minipumps to centrally infuse either a control scrambled (SCR) oligodeoxynucleotide (ODN) or a Gαi 2 targeted ODN, which downregulates CNS Gαi 2 proteins by ~85%, (25μg/5μl/day/ODN) were placed on a 1-7-day normal salt (NS; 0.6% NaCl) or HS diet (n=5/group) and underwent cardiac perfusion. Brain immunohistochemistry was used to assess PVN and subfornical organ microgliosis and qualitatively assess levels of PVN pro-inflammatory cytokines (PIC) IL-1β, IL-6, and TNFα. In additional groups, MAP was assessed via radiotelemetry, and whole blood and kidneys were obtained for ELISA measurement of plasma and renal norepinephrine (NE) as estimates of sympathetic tone. Results: By 24h in control SCR ODN infused rats a HS diet, which did not alter MAP or microglial activation, evoked sympathoinhibition. In contrast, in Gαi 2 ODN infused rats a HS diet did not result in sympathoinhibition and evoked significant increases in MAP, PVN microgliosis and PVN PIC expression within 24h, and elevated renal NE content by Day 3. Conclusions: Our data suggest that in the male Sprague-Dawley model of PVN Gαi 2 protein-dependent SSHTN PVN inflammation (microgliosis and PIC production) precedes sympathoexcitation.