Optimal electrocardiographic limb lead set for rapid emphysema screening

Figures & data

Table 1 Baseline characteristics of the study population

Variable	Emphysema patients (n = 100)	P value
Age (in years)	68.2 ± 9.86	–
Males (%)	41%	–
Frontal P axis (in degrees)	68.6 ± 11.4	–
Smoking history (%)	94%	–
Smoking pack-years	48.3 ± 28.5	–
FEV1 (%)	49.1 ± 17.8	–
r (FEV1 and frontal P axis)	−0.52	<0.001
Verticalization of P axis
By leads I and III (bipolar limb lead set)	88 (88%)	–
By lead aVL (unipolar limb lead)	66 (66%)	–

Notes: Data are represented as n, n (%), and mean ± standard deviation; r represents correlation coefficient between FEV₁ and P axis.

Abbreviation: FEV₁, forced expiratory volume in one second.

Table 2 P axis based on P wave morphology in leads I and III

P axis (n = 100)	Emphysema (n)
>60 degrees (P wave in lead III > I)	88 (88%)
60 degrees (P wave in lead III = I)	8 (8%)
<60 degrees (P wave in lead III < I)	4 (4%)

Note: Data are represented as n and n (%).

Table 3 P axis based on P wave morphology in lead aVL

P axis (n = 100)	Emphysema (n)
>60 degree (negative P wave in aVL)	66 (66%)
60 degree (equiphasic P wave in aVL)	22 (22%)
<60 degree (positive P wave in aVL)	12 (12%)

Note: Data are represented as n and n (%).

Figure 1 Electrocardiographic tracing representing a vertical P vector: P wave amplitude in lead III greater than P wave in lead I and an unequivocally negative P wave in aVL during sinus rhythm.