Changes in cardiac electrical biomarker with hyperaemic stress: an experimental perspective

Abstract

Abstract Background "Cardiac electrical biomarker" (CEB) is a numerical index measured by the Vectraplex ECG (vECG) System with Vectraplex AMI software that measures changes in the cardiac electrical field vectors from dipolar to multipolar during myocardial ischemia. CEB performs well in detecting NSTEMI and STEMI against physician adjudicated diagnosis. Purpose To assess changes in CEB during adenosine stress induced ischaemia. Method Thirty-three patients, in the VECTRA-PCI trial, with normal surface ECG (sECG) had CEB measured before (CEB0), at maximal hyperaemia (CEBh)) and 1-(CEB1), 2-(CEB2) and 3-(CEB3) hours after standard fractional flow reserve (FFR) assessment using intravenous adenosine. vECGs were adjudicated for quality by 2 blinded observers. vECGs with artefacts and arrhythmias were discarded and CEBs from best traces were analysed. Forty-nine individuals with non-cardiac chest pain, without past medical history or risk factors for CAD, on no medications, normal ECGs, normal blood profile acted as controls. CEBs (median, IQR) were compared using appropriate tests. Results FFR was normal (>/=0.80) (nFFR) in 25 and ischaemic (<0.80) (iFFR) in 8 patients. CEB0 in nFFR and iFFR groups were similar to each other (p=0.785) (Fig 1) and to controls (30.0; IQR 17.0-44.0, vs nFFR: p=0.057, vs iFFR: p=0.241). Compared to CEB0, CEBh was higher in nFFR (p=0.014) (Fig 1A) and iFFR (p=0.016) groups (Fig 1B). CEBh in iFFR (126.0; 109.5-216.0) higher than nFFR (44.0; 27.8-104.8), (p=0.039). In nFFR group, CEB1, 2 and 3, though numerically lower, were statistically similar to CEBh and CEB0 (Fig 1A) suggesting quick recovery. In iFFR group CEB1 was similar to and CEB2 and 3 were lower than CEBh (Fig 1B) suggesting a slower recovery of CEB. Both CEBh and change from CEB0 to CEBh (δCEB0-h), but not CEB0, predicted ischaemic FFR with similar accuracy (p=0.570) (Fig 2). CEBh >96 and δCEB0-h >28 had similar sensitivity of 87.5% with specificity of 68% and 80% respectively. Conclusion Obstructive coronary atheroma is associated with higher CEB than non-obstructive atheroma under hyperaemic stress. Both CEBh and δCEB0-h accurately predict ischaemic FFR with higher specificity of δCEB0-h. This is the first study to measure CEB changes with hyperaemic stress in patients with coronary artery disease and could have potential for wider clinical application. Figure 1. Changes in the CEB during and after hyperaemic stress in patients with normal (A) and ischaemic (B) FFR. Figure 2. Area under the ROC curve to determine the diagnostic accuracy of pre-procedural CEB, hyperaemic CEB and change in CEB from baseline to hyperaemia in determining ischaemic FFR.Fig 1. Changes in CEB with stress.Fig 2. CEB for ischaemic FFR