Coronary artery disease
Usefulness of Lung Impedance-Guided Pre-Emptive Therapy to Prevent Pulmonary Edema During ST-Elevation Myocardial Infarction and to Improve Long-Term Outcomes

https://doi.org/10.1016/j.amjcard.2012.03.009Get rights and content

Patients sustaining an ST-segment elevation myocardial infarction (STEMI) frequently develop pulmonary congestion or pulmonary edema (PED). We previously showed that lung impedance (LI) threshold decrease of 12% to 14% from baseline during admission for STEMI marks the onset of the transition zone from interstitial to alveolar edema and predicts evolution to PED with 98% probability. The aim of this study was to prove that pre-emptive LI-guided treatment may prevent PED and improve clinical outcomes. Five hundred sixty patients with STEMI and no signs of heart failure underwent LI monitoring for 84 ± 36 hours. Maximal LI decrease throughout monitoring did not exceed 12% in 347 patients who did not develop PED (group 1). In 213 patients LI reached the threshold level and, although still asymptomatic (Killip class I), these patients were then randomized to conventional (group 2, n = 142) or LI-guided (group 3, n = 71) pre-emptive therapy. In group 3, treatment was initiated at randomization (LI = −13.8 ± 0.6%). In contrast, conventionally treated patients (group 2) were treated only at onset of dyspnea occurring 4.1 ± 3.1 hours after randomization (LI = −25.8 ± 4.3%, p <0.001). All patients in group 2 but only 8 patients in group 3 (11%) developed Killip class II to IV PED (p <0.001). Unadjusted hospital mortality, length of stay, 1-year readmission rate, 6-year mortality, and new-onset heart failure occurred less in group 3 (p <0.001). Multivariate analysis adjusted for age, left ventricular ejection fraction, risk factors, peak creatine kinase, and admission creatinine and hemoglobin levels showed improved clinical outcome in group 3 (p <0.001). In conclusion, LI-guided pre-emptive therapy in patients with STEMI decreases the incidence of in-hospital PED and results in better short- and long-term outcomes.

Section snippets

Methods

This randomized 2-center study included patients admitted to the coronary care unit for STEMI without signs of acute heart failure on admission, i.e., with no dyspnea, at Killip class I with a normal chest x-ray, and without previous heart failure. During hospitalization, repeated lung auscultations were done, and respiratory rate, heart rate, blood pressure, and oxygen saturation were recorded every hour. Diagnosis of PED was based on chest x-rays and a modified Killip classification: class I,

Results

In the preliminary phase of the study, we evaluated 65 patients with STEMI (60 ± 12 years old) who had no clinical (Killip class I) or radiographic signs of PED at admission. During 72 hours of monitoring 33 patients with STEMI did not develop clinical and radiologic signs of PED and another 32 well-matched monitored patients developed PED (Killip classes IIA to IV). LI decreased in the former group during hospitalization by 0% to 14% from the initial value and in the latter group by 12% to 27%

Discussion

Current guidelines categorize acute heart failure into 6 different overlapping presentations,11 with PED in the course of AMI an important exception because it is a relatively uniform syndrome, especially for de novo acute heart failure. In this study we have reconfirmed our previous findings regarding LI changes throughout the evolution of PED in patients with STEMI and used LI as a trigger to initiate pre-emptive treatment. Use of a monitored signal to instigate therapy for evolving PED is of

Acknowledgment

We acknowledge the nursing staff and echocardiographic technicians of the Heart Institute, Hillel Yaffe Medical Center for their valuable contribution.

References (24)

  • M. Shochat et al.

    Prediction of cardiogenic pulmonary edema onset by monitoring right lung impedance

    Intensive Care Med

    (2006)
  • T.J. Noble et al.

    Diuretic induced change in lung water assessed by electrical impedance tomography

    Physiol Meas

    (2000)
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    Dr. Shochat and Dr. Rabinovich are members of the advisory board of the RSMM Company, Tel Aviv, Israel.

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