125 Cardiac Parasternal Long Axis View in Isolation: Is it Good Enough to Identify Pericardial Effusion, Left Ventricular Dysfunction and Right Ventricular dilation?

Abstract

Transthoracic focused cardiac ultrasound (FOCUS) is used clinically to identify etiologies of undifferentiated hypotension and shortness of breath in the emergency department (ED) and used to guide acute treatment. While a 4-view FOCUS examination is preferred to evaluate these patients, it is not always feasible due to patient body habitus, medical co-morbidities and clinician time constraints. The primary goal of this study was to determine the diagnostic accuracy of the parasternal long axis (PSLA) view in isolation for identifying pericardial effusion, left ventricular (LV) dysfunction and right ventricular (RV) dilation when compared to a 4-view FOCUS examination. This was a retrospective study looking at FOCUS images obtained on ED patients with a cardiovascular complaint. Examinations were blinded and randomized for review by point of care ultrasound faculty. Three faculty reviewed a full 4-view examination, while 2 others independently reviewed all PSLA images in isolation. Disagreements were adjudicated by a third reviewer. The primary objective was measured by comparing ultrasound findings on PSLA view in isolation to findings on a full 4-view FOCUS exam which served as the criterion standard. Sensitivity and specificity were calculated, as well as interobserver agreement using Kappa. We analyzed data on 100 FOCUS examinations; 16% had a pericardial effusion, 41% had an LV ejection fraction <50% (moderately reduced to poor LV function), 7% had RV dilation. Sensitivity and specificity for identifying pericardial effusion, LV dysfunction and RV dilation was 81% (confidence interval [CI] 0.54-0.95) and 98% (CI 0.91-0.99), 100% (CI 0.88-1) and 91% (CI 0.80-0.97), and 71% (CI 0.30-0.94) and 99% (CI 0.93-1), respectively. All moderate to large effusions were correctly identified. Interobserver agreement for faculty reviewing the PSLA images in isolation was k=0.72. Overall, there were 13 disagreements between PSLA alone and the 4-view interpretations. Four were clinically significant; 3 misclassifications of RV dilation, and 1 exam with normal LV ejection fraction on 4-view interpreted as severely reduced on PSLA view. The PSLA view in isolation is highly specific for identifying pericardial effusion and RV dilation, but only had moderate sensitivity. This single view had high sensitivity and specificity for diagnosing moderate to poor LVEF. This data supports the use of a single PSLA view for evaluating LVEF and ruling out moderate to large pericardial effusions. More views are necessary to rule out RV dilation.