LA Strain for Categorization of LV Diastolic Dysfunction

Abstract

Objectives: This study sought to observe the relationship between left atrial (LA) strain and left ventricular diastolic function and determine whether LA strain could be used to detect diastolic dysfunction (DD) and classify its degree when present.

Background: The assessment of diastolic function is complex and multiparametric because most conventional parameters do not follow the progression of DD. Strain imaging is an emerging index of LA function, with recent data demonstrating that LA strain is diminished in diastolic heart failure. However, LA strain is not part of the standard assessment of diastolic function. We hypothesized that LA strain decreases with worsening DD in a stepwise fashion and could thus be useful in evaluating DD.

Methods: We performed a retrospective derivation and validation cohort study to derive and test LA strain thresholds for DD grades (0 to 3) in patients with preserved left ventricular ejection fraction (N = 229). Two-dimensional speckle tracking was used to measure peak LA strain, which was applied as a single parameter to classify DD. American Society of Echocardiography guidelines were used as the reference standard.

Results: In the derivation cohort (n = 90), peak LA strain was significantly different between DD groups, with gradual decreases seen with worsening DD. Receiver-operating characteristic analysis resulted in 3 distinct LA strain thresholds for categorization of DD grades, with good to excellent diagnostic utility (area under the curve: 0.86 to 0.91). In an independent validation group (n = 139) with a spectrum of diastolic function, 11 patients (8%) had indeterminate DD grades using standard criteria, whereas LA strain was measured in all patients and its cutoffs resulted in diagnostic accuracy up to 95%.

Conclusions: LA strain measurements are feasible and allow accurate categorization of DD, because unlike the traditional parameters, it changes progressively with severity of DD. LA strain may become a useful tool for diastolic assessment in future clinical practice.

Keywords: diastolic function; left atrial strain; left atrium; myocardial strain.

Figure 1. Example of Speckle Tracking Analysis of LA Strain

The apical 4-chamber view with the entirety of the left atrium (LA) is pictured, with the endocardium of the LA traced (left). LA strain over time curve and an electrocardiogram signal are shown on the right.

Figure 2. Composite LA Volume Curves by DD Grade

Left atrial (LA) volume curves generated using 2-dimensional speckle tracking software over a single cardiac cycle. With increasing diastolic dysfunction (DD) grade, LA volumes also increase. Note that there is overlap in the volume curves for grades 1 and 2 DD suggesting that it would not be possible to distinguish between these 2 DD grades by LA volumes alone.

Figure 3. Composite LA Strain Curves for Individual DD Grades

At the 4 corners, composite LA strain curves are depicted as mean of each subgroup (solid lines) with standard deviation (dotted lines). Center panel shows all 4 LA strain curves in a single plot to facilitate comparisons. Abbreviations as in Figures 1 and 2.

Figure 4. Composite LV Strain Curves for Individual DD Grades

Subset of patients with longitudinal left ventricular (LV) strain curves shown by diastolic dysfunction (DD) grade, demonstrating that with grade 3 DD dysfunction there is a significant decrease in peak longitudinal strain of the LV, despite preserved ejection fraction. However, there is overlap of LV strain curves observed between grades 1 and 2 DD.

Figure 5. ROC Curves for LA Strain

Three distinct curves were obtained to differentiate grade 0 from grades 1 to 3 DD (left), grade 0 to 1 DD from grades 2 to 3 DD (middle), and grades 0 to 2 DD from grade 3 DD (right). ROC = receiver-operating characteristic; other abbreviations as in Figures 1 and 2.