B-Lines by Lung Ultrasound Can Predict Worsening Heart Failure in Acute Myocardial Infarction During Hospitalization and Short-Term Follow-Up

Abstract

Background: Acute myocardial infarction (AMI) with pulmonary edema shows a worse prognosis. Lung ultrasound (LUS) is a new tool for evaluating subclinical pulmonary congestion. It has been proved to predict prognosis in heart failure; however, whether it can be used as a short-term prognostic marker in AMI and provide incremental value to Killip classification is unknown.

Methods: We performed echocardiography and LUS by the 8-zone method in patients enrolled in Guangdong Provincial People's Hospital undergoing percutaneous coronary intervention for AMI from March to July 2021. The lung water detected by LUS was defined as B-lines, and the sum of the B-line number from 8 chest zones was calculated. Besides, the classification into LUS according to the pulmonary edema severity was as follows: normal (B-line numbers <5), mild (B-line numbers ≥5 and <15), moderate (B-line numbers ≥15 and <30), and severe (B-line numbers ≥30). The NT-proBNP analysis was performed on the same day. All patients were followed up for 30 days after discharge. The adverse events were defined as all-cause death, worsening heart failure in hospitalization, or re-hospitalization for heart failure during the follow-up.

Results: Sixty three patients were enrolled consecutively and followed up for 30 days. The number of B-lines at admission (median 7[3-15]) was correlated with NT-proBNP (r = 0.37, p = 0.003) and negatively correlated with ejection fraction (r = -0.43; p < 0.001) separately. In the multivariate analysis, B-line number was an independent predictor of short-term outcomes in AMI patients (in-hospital, adjusted OR 1.13 [95% CI: 1.04-1.23], P = 0.006; 30-day follow-up, adjusted OR 1.09 [95% CI: 1.01-1.18], P = 0.020). For in-hospital results, the area under the receiver operating characteristic curves (AUCs) were 0.639 (P = 0.093), 0.837 (P < 0.001), and 0.847 (P < 0.001) for Killip, LUS and their combination, respectively. For the diagnosis of 30-day adverse events, the AUCs were 0.665 for the Killip classification (P = 0.061), 0.728 for LUS (P = 0.010), and 0.778 for their combination (P = 0.002).

Conclusion: B-lines by lung ultrasound can be an independent predictor of worsening heart failure in AMI during hospitalization and short-term follow-up and provides significant incremental prognostic value to Killip classification.

Keywords: B-lines; acute myocardial infarction; heart failure; lung ultrasound; pulmonary edema.

Figure 1

Percentage of adverse events occurrence according to the LUS classification. LUS classification, the total number of B-lines was divided into four groups according to the severity of pulmonary edema (normal, B-line numbers <5; mild, B-line numbers ≥5 and <15; moderate, B-line numbers ≥15 and <30; severe, B-line numbers ≥30); In-hospital, during the hospitalization; 30 days, during 30 days follow-up.

Figure 2

Proportion of the severity of lung water in patients with Killip I–IV. Normal, B-line numbers <5; Mild, B-line numbers ≥5 and <15; Moderate, B-line numbers ≥15 and <30; Severe, B-line numbers ≥30.

Figure 3

Receiver operating characteristic curves for “Killip”, “LUS”, and “Killip+LUS” classification to predict the in-hospital and 30 days composite outcome. AUC, the area under the curve. In-hospital, during the hospitalization; 30 days, during 30 days follow-up; Killip, Killip classification; LUS, LUS classification; Killip+LUS, the combination of LUS and Killip classification.