102 Detection of Acute Coronary Syndrome by Magnetocardiography

Abstract

To evaluate the use of magnetocardiography (MCG) for early identification or rule out of acute coronary syndromes (ACS) in emergency department (ED) patients with chest pain. Magnetocardiography is a noninvasive imaging method that measures the electromagnetic fields generated by the heart’s activity. MCG is rapid, easy to perform, and provides a radiation-free imaging assessment for patients with suspected ACS. This is a prospective, observational, multicenter trial comparing the accuracy and time to disposition of ED standard of care (SOC) vs. MCG. Patients were enrolled at 3 sites from January to May 2021. Inclusion criteria were ED patients with chest pain, age ≥ 18 years, modified heart score > 2, and signs/symptoms of ACS in the ED. Exclusion criteria were STEMI, unable to fit into the device, non-ambulatory, hemodynamically unstable, and unable to lie supine for up to 5 minutes. Additional exclusion criteria were patients with pacemakers, AICD, other active devices, or any ferromagnetic metal above the costal margins. Patients underwent a MCG scan in addition to ED SOC. MCG was performed within 4 hours of ED triage. We hypothesize that the use of MCG will lead to shorter ED length of stay (LOS), with equal or improved diagnosis of suspected ACS patients. Of 58 scans, 32 were available for evaluation. 26 were unevaluable due to either insufficient data or uninterpretable. Patients with any artifacts were considered unevaluable. With technical improvements, the arttifact on current scans may be decreased which will result in fewer unevaluable scans. Mean age was 51.3 (SD± 1 .9) years, 50% female, 59.4% Black, 37.5% White, 3.1% other. Mean HEART score was 4.2 (SD± 1.1). Mean number of cardiovascular risk factors was 3.0 (SD± 1.6). Mean LOS (minutes) for MCG was 187 (SD ± 122) vs. SOC 812 (SD ± 73) (P < 0.0001 by paired t-test) (95% CI difference: -882.0, - 368.1). Thus, when compared with standard of care evaluation alone, the mean length-of-stay could have been reduced by 10.6 hours without any significant change in diagnostic accuracy. MCG and SOC based on troponins were both negative in 28 patients.There were 2 false positives by SOC (6.2%, 2/32). In these two patients presumed to have ACS by SOC, both went to cardiac catheterization, which revealed no ACS. MCG correctly identified the patients to have no ACS. There were two false negatives by MCG. In these two patients, MCG was positive and SOC rule out by troponins was negative. No stress test or cardiac catheterization was done in these two patients. Eleven patients (34%) were placed in the observation unit (OU). The MCG done in the ED and the rule out in the OU were both negative for ACS. Furthermore, early MCG done in the ED as compared with standard of care evaluation alone, would potentially eliminate overnight observation unit stays in 34% of the study population. Magnetocardiography results in a significantly lower LOS for chest pain in the ED which could lead to decreased ED LOS, improved ED turnaround times and better ED efficiency. MCG may avoid an OU stay with resultant cost savings in about one-third of ED chest pain patients. More importantly, MCG detected patients who were false positive by SOC and could have avoided a cardiac catheterization. MCG had two false positives which were negative by troponins but no cardiac catheterization or stress test were done in these two patients.