Relationship between iodine 123-metaiodobenzylguanidine pattern in the acute phase of Takotsubo syndrome and prognosis: a prospective cohort study

Abstract

Background: Takotsubo syndrome has always been thought to be a benign disease, but recent studies showed that its complications are similar to acute myocardial infarction (AMI). Complications are estimated to be 9,9% per person/year if we take into account major adverse cardiac events, such as recurrence, AMI, death and stroke. Its pathophysiology is not well established yet, but it seems to be related to sympathetic activity disturbance that can be demonstrated using simple photon emission computed tomography (SPECT) with iodine-123-metaiodobenzilguanidin (123I-MIBG). We know that there is a relationship between the pattern of sympathetic activity impairment in the acute phase and residual affection of 123I-MIBG uptake after 2 years of follow-up but it has not been demonstrated if this residual affection has a clinical relevance in the prognosis of this type of patients. Objective: The aim of this study is to determine if there is a relationship between the 123I-MIBG uptake pattern in the acute phase and prognosis, evaluated using major adverse cardiac events (MACE) (AMI, recurrence, re-admission, mortality from any cause and mortality from cardiovascular cause), after 3 years of follow-up. We are also interested in seeing if there are differences of each of the complications included in MACE between groups defined by Total Defect Score (TDS): TDS >8 or £8 and evaluate if the severity of the sympathetic activity impairment is also related to MACE. Study design, setting and subjects: This will be a prospective cohort, multi-centric study, with a consecutive method of sampling of patients attending the Coronary Unit with Takotsubo syndrome that meet inclusion criteria. Eleven hospitals from Catalonia will participate in the study. The sample size will be 782 patients with Takotsubo syndrome that meet Mayo clinic criteria diagnosed in the Coronary Unit. Methods: The main variables of this study are the acute phase pattern of 123I-MIBG uptake and long-term prognosis after 3 years of follow-up. This prognosis will be evaluated with the occurrence of any MACE. The patients will be classified in two groups depending on the extension of cardiac sympathetic activity affection: Group 1 moderate and severe affection (TDS >8) and Group 2 normal or mild affection (TDS £8). These patients will be followed-up for 3 years. The multivariate analysis will be done using COX model