Abstract 2746: Acute Heart Failure in the Course of Acute Myocardial Infarction: A Preventable Complication?
Background:patients sustaining an acute myocardial infarction (AMI) frequently develop acute heart failure (AHF) during admission. Recently it was shown that lung fluid overload (LFO) during the development of heart failure may be effectively monitored using impedance technique, either by using implantable pacemaker or by surface thoracic impedance monitor. LFO during AHF results in lower internal thoracic impedance (ITI). AHF evolves through 2 phases. In the first there is interstitial congestion with no clinical signs of edema (preclinical phase). The second phase, during which lung alveoli begin to fill with fluid, manifests as clinically overt alveolar edema. Treatment of AHF may be initiated only after the appearance of clinical signs of LFO.
Aim:we studied the ability of a new surface thoracic impedance monitor to determine LFO at the preclinical stage of AHF in the course of an AMI and of early impedance-guided treatment to prevent development of the overt phase of AHF.
Results:486 patients with AMI underwent impedance monitoring during the first 72 hours after admission. No clinical and rentgenological signs of AHF were present on admission. 364 patients did not develop signs of LFO during monitoring and their ITI decreased from initial level by 5.6% only (95%CI, 0 to 12%, p=0.6). 90 patients developed overt AHF. At the preclinical stage of AHF ITI decreased from initial value by 16.3% (CI,12.4 to 20.2%, p<0.001) while at the time of appearance of lung rales (clinical signs of AHF) ITI decrease was 19.9% (CI,13.1 to 26.7%, p<0.001) and at the peak of pulmonary congestion ITI decreased by 35.8%, (CI,20.6 to 51%, p<0.0001). After successful treatment ITI returned to its initial value. In 32 patients we started ITI guided treatment at the preclinical stage of AHF when ITI decrease was 15.5% (CI,12.1 to 18.9%, p<0.001). Only 4 patients of group 3 (12.5%) developed clinically overt AHF and in all others early treatment was successful. It means, early ITI guided treatment significantly reduced AHF development (χ2 < 0.001).
Conclusion. Using surface impedance monitoring in the course of AMI provides a reliable diagnosis of AHF at its preclinical stage and impedance guided initiation of treatment at this stage prevents the development of overt AHF in 87% of patients.