Potential Significance of Spontaneous and Interventional ST-changes in Patients Transferred for Primary Percutaneous Coronary Intervention: Observations from the ST-MONitoring in Acute Myocardial Infarction Study (The MONAMI Study)

Aims: In patients with ST-elevation myocardial infarction (STEMI) scheduled for primary percutaneous coronary intervention (primary PCI), acute risk-assessment may be valuable for tailoring of adjunctive therapy at the time of coronary intervention. The present study was designed to quantify pre-, per-, and post-interventional ST-changes, to evaluate whether a pre-specified continuous ST-monitoring classification provides potential prognostic information in the pre- and per-interventional phase, and to compare post-interventional ST-resolution parameters derived from continuous ST-monitoring and snapshot ECGs, respectively.

Methods And Results: In 92 STEMI patients, continuous ST-monitoring was initiated in the pre-hospital phase and continued during and 90 min following PCI. Patients were divided into three groups: (A) patients achieving spontaneous ST-resolution before PCI; (B) patients with preserved ST-elevation immediately before PCI and with no increase in ST-elevation during PCI; and (C) patients with preserved ST-elevation immediately before PCI and with increase in ST-elevation during PCI. Groups A (n=22), B (n=43), and C (n=27) differed in peak level of troponin-T (1.4, 4.7, and 7.2 microg/L, P<0.001), creatinine kinase MB isoenzyme (35, 150, and 325 microg/L, P<0.001), and N-terminal pro-brain natriuretic peptide (Nt-pro-BNP) (183, 175, and 269 pmol/L, P=0.084) during admission, and left ventricular ejection fraction evaluated within 2 h of PCI (0.53, 0.48, and 0.45, P=0.047) and after 3 months (0.58, 0.54, and 0.45, P<0.001). Groups B and C also differed in time from first balloon inflation to > or =70% resolution of ST-elevation (14 vs. 42 min, P=0.002), whereas no differences were observed in traditional 90 min ST-resolution analysis or angiographically assessed parameters.

Conclusion: STEMI patients transferred for primary PCI are heterogeneous with respect to pre- and per-interventional ST-changes, and a pre-specified ST-monitoring classification seems useful for stratification of patients at time of PCI into groups with low, intermediate, and high risk profile. Furthermore, post-interventional ST-monitoring indicates that traditional 90 min ST-resolution analysis may have limited value in the era of primary PCI.