Our study included 218 NSTEMI patients who presented to our institution and underwent coronary angiography within 24 hours of admission. For convenience, ¡®N¡¯ wave was defined as a notch or deflection in the terminal QRS complex of the surface ECG. The duration of QRS with N wave before PCI was more prolonged than the duration of QRS without N wave (121 ¡À 12 ms vs 106 ¡À 11 ms, P < 0.01). In the LCX group, 66(77 % ) patients had N wave in leads II, III and aVF, whereas only 5(6 % ) patients in the LAD group and 9(18 % ) patients in the RCA group had such ECG feature (P < 0.001). A greater proportion of patients in the LCX group also had N waves in leads I and aVL (P < 0.001). N wave in leads II, III and aVF was associated with 77 % sensitivity and 89 % specificity, respectively. N wave in leads I and aVL was associated with 64 % sensitivity and 96 % specificity, respectively.
The abnormal waveform in terminal QRS complex in NSTEMI ,which is described above, is the delayed activation wave of left ventricular basal region which the left circumflex artery supplies. It is associated with a higher specificity and higher sensitivity for culprit LCX in non-ST-elevation myocardial infarction. The delayed activation wave is a new pattern of ischemia in ECG.