Cardiac electrical biomarker (CEB), an indicator of ischaemia-induced change in myocyte polarity, has been proposed for diagnosis of acute coronary syndrome. However, effect of coronary occlusion on CEB has not been demonstrated. CEB was acquired before (CEB0), during maximal adenosine hyperaemia (CEBhyp), balloon inflations (CEBmax) and 1 (CEB1h), 2 (CEB2h) and 3 (CEB3h) h after percutaneous coronary intervention along with pre- and post-procedural troponin-I. CEB of subjects with non-cardiac chest pain without risk factors was used as controls (CEBc). “Late recovery” (LR) of CEB was defined as CEB3h > median-CEB0. CEB was recorded in 75 patients undergoing stenting (group 1) including 8 with FFR < 0.8 (group 1a), 25 with FFR ≥ 0.8 (group 2) and 49 controls. In group 1, CEB0 (median, IQR) was higher than CEBc (48.0; 29.5–88.3 vs 30.0; 17.0–44.0; p < 0.001). CEBmax (185; 105.0–331.0) was higher than CEB0 (p < 0.0001). CEB1h (78.0; 31.5–143.8; p < 0.0001) and CEB2h (63.0; 31.5–114.3; p = 0.039) were higher than CEB0 while CEB3h (54.0; 24.3–94.8, p = 0.152) was similar. LR occurred in 50.7% patients. CEBmax predicted LR (OR 1.01, 95% CI 1.00–1.01, p < 0.001) (AUC 0.759, p < 0.001). CEB0 in group 1a and group 2 were similar (p = 0.524). CEBhyp was higher than CEB0 in group 1a (126.0, 109.5–266.0 vs 47.5, 20.5–73.5; p = 0.016) and group 2 (44.0, 27.8–104.8 vs 39.0, 24.0–90.3; p = 0.014). CEBhyp was higher in group 1a than 2 (p = 0.039). CEBhyp (AUC 0.75, p = 0.017) accurately predicted FFR < 0.8. Coronary arterial occlusion increases CEB that retains a “memory” of the ischaemic event. CEBhyp was higher only when FFR was ischaemic and accurately identified FFR < 0.8.