Figure 1.
P wave and Left Atrial Area Quantification.
Representative examples of LA quantification methods: For ECG (top), total P wave area was quantified based on geometric area (green shading) between the electrical waveform and the isoelectric line. Corresponding indices of amplitude (red line) and duration (blue line) were measured within the total P wave complex, as well as its positive and negative components. For CMR (bottom), LA area was measured by planimetry of chamber borders (green line) at ventricular end-systole. Note heterogeneity in P wave morphology among patients with LA enlargement: Whereas both patient examples demonstrate LA dilation by CMR, a bimodal P wave with large negative terminal component is present in 1A, whereas a bifid but upright P wave is present in 1B.
Table 1.
Clinical and Imaging Characteristics in Relation to the Presence or Absence of Left Atrial Dilation.
Table 2.
Lead V1 P wave Measurements in Relation to the Presence or Absence of Left Atrial Dilation.
Figure 2.
Scatter plots relating CMR-quantified LA size to P wave morphology as measured in ECG lead V1. Data presented for total P wave area (1A), negative terminal area (1B), duration (1C), and maximum amplitude (1D). Patient data stratified based on normal (grey) and dilated (black) left atrial size on cine-CMR using an established diagnostic cutoff (>15 cm2/m2) [19].
Figure 3.
Mitral Regurgitation Severity.
P wave area in lead V1 (mean ± standard deviation) in relation to MR severity on cine-CMR (3A) and echo (3B). Note that P wave area increased stepwise in relation to MR severity as measured by both modalities, with greatest magnitude of increase at a threshold of moderate-severe MR (black bars).
Figure 4.
Pulmonary arterial systolic pressure (mean ± standard deviation) among population subgroups stratified based on lead V1 P wave area quartiles (≤1.92 | 1.93–2.70 | 2.71–3.65 | >3.65 mV·msec). Black bar = top P wave area quartile.
Table 3.
Multivariate Models for Prediction of Increased P wave Area in Lead V1* in Overall CMR Population.
Table 4.
Multivariate Models for Prediction of Increased P wave Area in Lead V1* in Echocardiography Sub-group.
Figure 5.
Atrial Fibrillation/Flutter Risk as Stratified by LA Remodeling Indices.
Kaplan-Meier plots relating baseline P wave area (5A) and body surface area indexed LA area (5B) to follow-up risk for AF/AFl. Note that both ECG and CMR indices demonstrated increased risk for AF/AFl among patients in the highest quartile of LA remodeling.