Occurrence of Transient Myocardial Ischemic Events Among Non-ST Segment Elevation Acute Coronary Syndrome Patients Before or After Invasive Coronary Angiography.

Background: The occurrence of transient myocardial ischemia (TMI) is an important pathology in patients with non-ST elevation acute coronary syndrome (NSTE-ACS), yet studies are scarce regarding when TMI occurs during hospitalization, particularly in relation to invasive coronary angiography (ICA). This study examined: (1) TMI before or after ICA; (2) patient characteristics and ischemic burden by TMI group (before or after ICA); and (3) major in-hospital complications (transfer to critical care, death) and length of stay by TMI group (before or after ICA).

Methods: Secondary data analysis in hospitalized NSTE-ACS patients with TMI event(s) identified from 12-lead electrocardiographic Holter. Patient records were reviewed to assess ischemic burden [TMI time (min) ÷ hours recording duration], outcomes, and TMI timing, before or after ICA.

Results: In 38 patients, 3 (8%) had TMI before and after ICA. Of the remaining 35 patients (92%), TMI occurred before ICA (16; 46%), and after ICA (9; 26%), and 10 (28%) did not have ICA. Patient characteristics, untoward outcomes, and TMI duration (minutes) did not differ by group. Ischemic burden was higher in patients with TMI after ICA (7.29 ± 8.82 min/h) compared to before ICA (2.54 ± 2.11 min/h), P = 0.039. Hospital length of stay by TMI group was 113 ± 113 (before), 226 ± 244 (after), and 85 ± 65 hours (no ICA); P = 0.172.

Conclusions: Almost half of the sample had TMI before ICA; one-third had TMI but did not have ICA. Patients with TMI after an ICA had a higher ischemic burden. Future studies with larger sample sizes are needed to investigate further the short- and long-term clinical significance of TMI among NSTE-ACS patients.