Combining baseline clinical descriptors and real-time response to therapy: the incremental prognostic value of continuous ST-segment monitoring in acute myocardial infarction.

Background: Clinical descriptors and ST-segment recovery variables hold prognostic information for clinical outcome after thrombolysis for acute myocardial infarction (MI). We sought to define the incremental prognostic value of continuous 12-lead ST-segment monitoring variables to clinical risk descriptors identified by the Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries (GUSTO-I) trial 30-day mortality analysis.

Methods: Of 1,777 patients enrolled in continuous ST-segment substudies from the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI-9), GUSTO-I, Duke University Clinical Cardiology Study (DUCCS-II), Integrilin to manage Platelet Aggregation to Combat Thrombus in Acute Myocardial Infarction (IMPACT-AMI), Promotion of Reperfusion by Inhibition of Thrombin During Myocardial Infarction Evolution (PRIME), and Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction (PARADIGM) trials, 825 patients qualified for assessment of time to recovery. ST recovery variables analyzed were time to stable ST-recovery and late ST elevation. Patients who were at low clinical risk (n = 261) had no high-risk descriptors, and patients at high clinical risk (n = 564) had at least 1 of these high-risk descriptors: age >or=70 years, systolic blood pressure or=90 beats/min, anterior MI, or previous MI. High (n = 90), moderate (n = 318), and low (n =417) ST-risk groups were defined by the presence of both slow ST recovery and late ST elevation, one or the other, or neither, respectively. End points analyzed were inhospital death and combined death, reinfarction, or congestive heart failure.

Results: There was a trend toward increased mortality rate in the high-clinical/high-ST-risk group. For the composite end point, ST subgrouping resulted in significant event stratification in both patients at low and high clinical risk. In multivariable analysis, age and heart rate were independent predictors of both mortality and the composite end point. Late ST elevation added incremental prognostic information.

Conclusion: Age, heart rate, and late ST elevation are powerful, independent predictors of adverse clinical outcome. Continuous monitoring allows noninvasive assessment of the response to therapy. Consequently, this technique will enhance the potential to risk-stratify individual patients in a real-time setting.