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B-lines in lung ultrasound scores were a viable tool for identifying heart failure in patients experiencing chronic obstructive pulmonary disease exacerbations.
Quantifying B-lines on lung ultrasound is a viable tool for identifying heart failure in patients with COPD who are experiencing exacerbations, according to findings published in the International Journal of Chronic Obstructive Pulmonary Disease.
Heart failure is estimated to contribute to as many as 30% of acute exacerbations in COPD, but current methods for detecting heart failure in this setting are limited.
Opportunity for Improved Heart Failure Identification
“Identifying cardiac origin in [acute exacerbations of] COPD is challenging and necessary for appropriate management of these patients. The coexistence of several comorbidities and pathologies causing dyspnea makes etiological diagnosis more difficult,” Fadwa Lajili, a researcher at Monastir University, Monastir, Tunisia, and colleagues wrote.
“Conventional, complementary tests such as chest X-ray and brain natriuretic peptide BNP lack specificity and/or sensitivity while cardiac ultrasound requires training and [is] not always… available in the ED. [Lung ultrasound score], an easily feasible and non-invasive tool performed by clinicians at the bedside with portable devices, might enhance the diagnosis accuracy… However, its value in AECOPD patients has not been well evaluated.”
The researchers conducted a multicenter, cross-sectional, prospective cohort study of 380 adults who presented at three emergency rooms in Tunisia with acute exacerbations of COPD. Patients who were hemodynamically unstable, respiratorily unstable, or who were in altered states of unconsciousness as measured by a Coma Score of 13 or greater were excluded from the study, as were patients whose exacerbations were a result of trauma and those who did not consent to participate in the study.
All patients in the study underwent lung ultrasound scoring and were divided into two subgroups: those with heart failure (41.4%; n=157) and those without heart failure (58.6%; n=223). Two qualified emergency room physicians performed lung ultrasounds on each patient, assigning a score derived from the total of B-lines found in four zones of each lung. A score of 15 or greater indicated the presence of heart failure.
The researchers independently diagnosed heart failure by performing clinical examinations, evaluating pro-brain natriuretic peptide levels, and consulting echocardiographic findings.
The patients were a mean of 68 years old; however, the two subgroups were lopsided, with the average age of patients in the heart failure group being 70 years old, compared with 66.5 years in the non-heart failure group (P=.04). Hypertension was the most common comorbidity, occurring in 44.5% of patients, followed by diabetes (35%) and chronic heart failure (17.9%). The heart failure group also had a significantly greater incidence of comorbidities such as renal failure, coronary artery disease, diabetes, and hypertension.
The researchers reported that patients in the heart-failure group had an average left-ventricular ejection fraction (LVEF) of 47.2, whereas those in the non-heart failure group had an average LVEF of 58.6. LVEF was reportedly preserved in 35.6% of patients with heart failure.
Lung Ultrasound B-lines Performed
The heart failure group had a mean lung ultrasound score of 26.8, significantly higher than that of the non-heart failure group’s average of 15.3, according to Lajili and colleagues (P<0.01).
The researchers wrote that more than half of the total study population (52.1%) had a lung ultrasound score of more than 15. They added that lung ultrasound B-lines were useful in identifying heart failure, with a reported area under the ROC curve of 0.71 (0.65–0.76) for diagnosing heart failure.
With a threshold score of 15, “which appears to be associated with the best performance,” the lung ultrasound score had a sensitivity of 73% (68.5–77.5) and a specificity of 62% (57.1–66.9). Lung ultrasound also showed a positive predictive value of 58% (53–63) and a negative predictive value of 75% (70.6–79.4).
The best sensitivity in the study reportedly occurred at a threshold score of 5, with a sensitivity of 89% (85.9–92.1), whereas the best specificity occurred at a threshold of 30, with a specificity of 85% (81.4–88.6).
“Our study showed that discriminatory power of the lung ultrasound score in the diagnosis of [heart failure] in [acute exacerbations of] COPD is acceptable,” the researchers wrote. “At a cutoff of 5, [lung ultrasound score] had a good sensitivity; and at a cutoff of 30, [lung ultrasound] score had a good specificity. More precisely, a [lung ultrasound] score below 5 can help to exclude [heart failure], while patients with [lung ultrasound] score[s] over 30 are more likely to have [heart failure]. Lung ultrasound score values were not different between patients with [heart failure and reduced] LVEF and those with [preserved] LVEF; they were correlated with the E/e’ ratio, which is considered a surrogate parameter of left ventricular filling pressure.”
