A portable prototype magnetometer to differentiate ischemic and non-ischemic heart disease in patients with chest pain

Background: Magnetocardiography (MCG) is a non-invasive technique used to measure and map cardiac magnetic fields. We describe the predictive performance of a portable prototype magnetometer designed for use in acute and routine clinical settings. We assessed the predictive ability of the measurements derived from the magnetometer for the ruling-out of healthy subjects and patients whose chest pain has a non-ischemic origin from those with ischemic heart disease (IHD). Methods: MCG data were analyzed from a technical performance study, a pilot clinical study, and a young healthy reference group. Participants were grouped to enable differentiation of those with IHD versus non-IHD versus controls: Group A (70 IHD patients); Group B (69 controls); Group C (37 young healthy volunteers). Scans were recorded in an unshielded room. Between-group differences were explored using analysis of variance. The ability of 10 candidate MCG predictors to predict normal/abnormal cases was analyzed using logistic regression. Predictive performance was internally validated using repeated five-fold cross-validation. Results: Three MCG predictors showed a significant difference between patients and age-matched controls (P<0.001); eight predictors showed a significant difference between patients and young healthy volunteers (P<0.001). Logistic regression comparing patients with controls yielded a specificity of 35.0%, sensitivity of 95.4%, and negative predictive value for the ruling-out of IHD of 97.8% (area under the curve 0.78). Conclusion: This analysis represents a preliminary indication that the portable magnetometer can help rule-out healthy subjects and patients whose chest pain has a non-ischemic origin from those with IHD

Apparent and cross-validation performance of the logistic regression models.

<p>Apparent and cross-validation performance of the logistic regression models.</p

Histogram of the RS_peak predictors.

<p>A representative histogram of the RS_peak predictors for study participants enrolled in Group A, Group B, and Group C.</p

Average value for each predictor for patient and control groups.

<p>Average value for each predictor for patient and control groups.</p

CONSORT Diagram: Technical performance study.

<p>Participant flow through the technical performance study. Data were analyzed for 55/63 patients and 51/60 healthy controls.</p

Confusion matrix for a binary classifier.

<p>Confusion matrix for a binary classifier.</p

CONSORT Diagram: Pilot clinical study.

<p>Participant flow through the pilot clinical study. Data were analyzed for 15/21 patients and 18/21 healthy controls.</p