The "false-positive" conundrum: IgA reference level overestimates the seroprevalence of antibodies to SARS-CoV-2.

BACKGROUND: On 12 June 2020, Brazil reached the second position worldwide in the number of COVID-19 cases. Authorities increased the number of tests performed, including the identification of antibodies to SARS-CoV-2 (IgG, IgA, and IgM). There was an overflooding of the market with several tests, and the presence of possible false-positive results became a challenge. The purpose of this study was to describe the seroprevalence and immunoglobulin blood levels in a group of asymptomatic individuals using the reference levels provided by the manufacturer. METHODS: Levels of IgG and IgA antibodies to SARS-CoV-2 were determined in blood serum by the same ELISA (enzyme-linked immunoassay) test. Patients must be free of symptoms. RESULTS: From 20 to 22 May 2020, 938 individuals were tested. There were 441 (47%) men, age 53 years (interquartile range (IQR) = 39-63.2). The sample included 335 (35.7%) subjects aged ≥60 years old. Subjects with a positive test were 54 (5.8%) for IgG and 96 (10.2%) for IgA and 42 (4.5%) for both IgG and IgA. The prevalence of IgG and IgA positive test was not different in men and women and not different in individuals under 60 and over 60 years of age. Conversely, analysing only individuals with positive tests, the levels of IgG in positive subjects were significantly higher than those with an IgA positive test, 3.00 (IQR = 1.68-5.65), and 1.95 (IQR = 1.40-3.38), respectively; P = 0.017. Additionally, individuals with isolated IgA positive tests had significantly lower levels of IgA than those with both IgA and IgG positive tests: 1.95 (IQR = 1.60-2.40) and 3.15 (IQR = 2.20-3.90), respectively, P = 0.005. These latter data suggest that IgA shows a deviation of the distribution to the left in comparison to IgG distribution data. Indeed, many subjects reported as IgA positive had immunoglobulin levels slightly elevated. CONCLUSIONS: In conclusion, we strongly suggest caution in the interpretation of IgA test results. This recommendation is more important for those with positive IgA just above the reference level.

PCI in a case of dual (type IV) LAD with anomalous origin of the LCx from RCA.

Dual left anterior descending coronary artery (LAD) originating from the left main stem and the right coronary artery (type IV LAD) is a rare congenital anomaly. Its association with an anomalous origin of the left circumflex (LCx) from RCA is even rarer. We describe a patient presenting with acute inferior wall myocardial infarction, who was subsequently found to have this coronary anomaly. He underwent staged PCI of the dominant RCA and anomalous LCx successfully through the radial route. We conclude that anomalous coronaries can be safely and successfully treated through the radial route after careful evaluation of origin and course of the anomalous vessels. CT coronary angiography is extremely useful in delineating the vessel course and particularly their relation to great arteries.

Collateral approach for LV lead implantation in a case with abnormal venous anatomy.

A 75-year-old man, 8 years after CABG, with ischemic cardiomyopathy underwent cardiac resynchronization therapy (CRT) for refractory heart failure. Retrograde occlusion venography revealed absence of lateral vein. A functionally occluded middle cardiac vein with branch to anterolateral vein was used for left ventricular lead implantation. Using a collateral route for left ventricular lead implantation is a new technique. Lead position was stable with excellent threshold. Follow-up at 6 months reveals continued stable lead position.

A tale of early Reel syndrome caused by an over-enthusiastic masseuse.

Twiddler syndrome is a form of pacemaker lead dislocation caused by the coiling of the pacemaker leads due to pulse generator rotation on its long axis. Similar to Twiddler syndrome, Reel syndrome occurs due to rotation of the pulse generator on its transverse axis, leading to lead dislocation or fracture, followed by clinical symptoms of dislodged leads. We report a case of 75 years old woman with Reel syndrome presenting with syncope.

Piperacillin and vancomycin induced severe thrombocytopenia in a hospitalized patient.

In hospitalized patients with complex medical problems on numerous drugs, thrombocytopenia may have a multiple confounding etiology. Keeping this in mind, it is of utmost importance to monitor the platelet count regularly during hospitalization and on subsequent follow-up visits, even after the most probable etiology has been identified/most likely causative drug has been withdrawn. Isolated thrombocytopenia with no evidence of microangiopathic hemolysis on the peripheral blood smear in an acutely ill hospitalized patient implicated sepsis, disseminated intravascular coagulation and drugs as the most probable causes. Our patient represents an uncommon case of antibiotic-induced severe immune thrombocytopenia, as he developed both vancomycin-dependent and piperacillin-dependent antibodies, while being treated for cellulitis (vancomycin-specific antibodies of the IgG isotype, and both IgG and IgM antibodies specific for piperacillin were identified in laboratory testing). Vancomycin was stopped before the reports were available. Following this, the patient's platelet count showed a transient upward trend, but then the thrombocytopenia worsened drastically reaching a nadir of 10,000/µL. The platelet count returned to normal only after piperacillin/tazobactam was stopped after a week, thus establishing it as the cause of the more severe thrombocytopenia, which occurred later on; this was subsequently confirmed by the laboratory results. Vancomycin is an established cause of drug-induced immune thrombocytopenias, especially in acutely ill, hospitalized or elderly patients, whereas incidents of piperacillin/tazobactam-induced immune thrombocytopenia are uncommon. In case clinical suspicion is high, workup should include immunoprecipitation and flow cytometry studies to confirm antiplatelet antibodies.