The delayed activation wave in non-ST-elevation myocardial infarction

Non‐ST‐elevated myocardial infarction with “N” wave on electrocardiogram and culprit vessel in left circumflex has a risk equivalent to ST‐elevated myocardial infarction

“…The detection sensitivity is very low (approximately 32%~50%) for acute occlusion in the LCX, electrocardiogram was mostly NSTEMI . This may be because LCX is located on the posterolateral side of the heart, mainly supplying the lateral and posterior walls of the basal part of the left ventricle, far from the chest wall, and lacking suitable leads for electrocardiogram, called the “blind area.” Niu et al were the first to report delayed activation wave (“N” wave) in NSTEMI patients with culprit vessel in LCX. Angiography showed that in NSTEMI patients with “N” wave on electrocardiogram, 77% of the culprit vessels were in the circumflex artery, 6% were in the left anterior descending and 18% were in the right coronary artery, and the sensitivity and specificity of “N” wave for detection the left circumflex artery lesions were 77% and 96%.…”

“…According to the following criteria, a “N” wave was considered present in the ECG: (a) a notch or deflection in the terminal QRS complex of the surface ECG (Figure , red arrow, A1, A2, A3); (b) the height of notch or deflection of ≥2 mm (the point of deflection was measured with reference to the PR segment); (c) a continuous change of the notch (the point of deflection shifted ≥2 mm with reference to the PR segment, ≥2 leads) in 24 hours, even disappeared or come into the “s” wave (Figure , red arrow, B1, B2, B3); (d) with a prolongation of QRS wave duration in these leads. We list the electrocardiograms and coronary angiograms of three N‐NSTEMI cases in Figure , the results of coronary angiography corresponding to ECG before PCI are shown in Figure (red arrow, C1, C2, C3), and the coronary angiography results of these three patients after PCI are shown in Figure (red arrow, D1, D2, D3).…”

“…Recently, there has been a shift in the literature towards finding novel electrocardiogram (ECG) changes, which are highly suggestive of total coronary artery occlusion, but lack ST‐elevation in contiguous leads . These ST‐elevated myocardial infarction (STEMI)‐equivalents include delayed activation wave (N wave, notch in terminal QRS wave complex II, III, aVF, or I, aVL).…”

“…These ST‐elevated myocardial infarction (STEMI)‐equivalents include delayed activation wave (N wave, notch in terminal QRS wave complex II, III, aVF, or I, aVL). In their preliminary study, Niu et al reported an ECG phenomenon in acute non‐ST‐elevated myocardial infarction (NSTEMI) patients with the culprit vessel in left circumflex artery (LCX): a turning point or notch appeared at the terminal part of the QRS wave complex in leads II, III, and AVF or leads I and AVL, which was called “N” wave. The sensitivity and specificity of “N” wave for detection of circumflex artery lesions were 77% and 96%.…”

“…The sensitivity and specificity of “N” wave for detection of circumflex artery lesions were 77% and 96%. The specificity of the “N” wave on the relevant ECG leads detecting acute NSTEMI with LCX culprit vessel was 96% . However, the role of “N” wave in NSTEMI patients with culprit LCX artery has not yet fully understood.…”