A new method to determine the QRS axis—QRS axis determination

BACKGROUND: The development of a perfect method for determining the mean QRS axis (ÂQRS) is still lacking. HYPOTHESIS: We proposed a new simple method, whether this method is accurate is unknown. METHODS: The axis perpendicular to the mean QRS axis (P‐ÂQRS) divides six limb leads into two groups. All the leads that are in the range of 180° along the ÂQRS are positive, while all the leads in another 180° are negative, one lead is isodiphasic if it is on the P‐ÂQRS. If no lead is isodiphasic, then the P‐ÂQRS is located in the middle of two adjacent leads, which can help us determine the P‐ÂQRS. The six limb leads that fall in the range of −30° to 120° are as follows: aVL (−30°), I (0°), −aVR (30°), II (60°), aVF (90°), and III (120°). We can check an external lead (aVL or III) first. For example, if lead III is isodiphasic and lead aVF is positive, the P‐ÂQRS is 120°; if lead III is negative and lead aVF is positive, then the P‐ÂQRS is 105°. If more than one lead is negative, all such leads can be checked individually until a positive or isodiphasic lead is found. The ÂQRS can be easily decided once we know the P‐ÂQRS. In total, 200 recorded ECGs were investigated. We obtained the ÂQRS from our new method, computer interpretations, and a standard bipolar method. The Pearson correlation coefficient and Bland‐Altman analysis were performed. RESULTS: The mean and SDs were remarkably similar, the correlation coefficient between the P‐ÂQRS method and the bipolar method was 0.976 (P < .001). Mean bias (Bland‐Altman limits of agreement) between the two methods was 0.885 (−12.37 to 14.14). CONCLUSION: The new method is simple and is able to assess the mean QRS axis accurately.