Background
Treatment for unstable angina (UA) or non-STEMI (NSTEMI) is aimed at plaque stabilization to prevent infarction. Two treatment strategies are: (1) invasive (i.e., cardiac catheterization laboratory < 24 hours after admission), or (2) selectively invasive (i.e., medications with cardiac catheterization laboratory > 24 hours for recurrent symptoms). However, it is not known if the frequency of transient myocardial ischemia (TMI), or complications during hospitalization varies by treatment.
Purpose
We examine; (1) occurrence of TMI in UA/NSTEMI, (2) compare frequency of TMI by treatment pathway and (3) determine predictors of in-hospital complications (i.e., death, MI, pulmonary edema, shock, arrhythmia w/intervention).
Method
Hospitalized patients with CAD (i.e., history of MI, PCI/stent, CABG, > 50% lesion via angiogram, or positive troponin) were recruited and 12-lead ECG Holter initiated. Clinicians, blinded to Holter data, decided treatment strategy; off-line analysis was done post discharge. TMI was defined as > 1 mm ST-segment ↑ or ↓, in > 1 ECG lead, > 1 minute.
Results
Of 291 patients, 91% were white, 66% male, 44% prior MI, and 59% prior PCI/stent or CABG. Treatment pathway was early in 123 (42%), and selective in 168 (58%). Forty-nine (17%) had TMI; 19 (15%) early invasive, 30 (18%) selective (p = 0.637). Acute MI after admission was higher in patients with TMI regardless of treatment strategy (early no TMI 4% vs yes TMI 21%; p = 0.020; selective no TMI 1% vs yes TMI 13%; p = .0004). Predictors of major in-hospital complication were TMI (OR 9.9; 95% CI, 3.84 to 25.78), and early invasive (OR 3.5; 95% CI, 1.23 to 10.20).
Conclusions
In UA/NSTEMI patients treated with contemporary therapies, TMI in not uncommon. The presence of TMI and early invasive treatment are predictors of major in-hospital complications.