ST-elevation myocardial infarction (STEMI) is a severe type of heart attack that occurs when a coronary artery becomes fully blocked, cutting off blood flow to the heart muscle. Restoring that blood flow quickly, known as reperfusion, is critical to limiting damage. Two common reperfusion approaches exist: primary percutaneous coronary intervention (PCI), an immediate catheter-based procedure to open the blocked artery, and a pharmacoinvasive strategy, which combines clot-dissolving medication with a follow-up catheter procedure. Previous research suggested that Q waves, a specific pattern on an electrocardiogram (ECG) that can signal more advanced muscle damage, may predict outcomes better than duration of symptoms as reported by the patient. Whether the choice of reperfusion strategy can be influenced by Q wave status on the baseline ECG remains to be determined.
In this recently published study, researchers examined 967 patients from Alberta’s STEMI Vital Heart Response registry (2017–2021), grouping them by the presence (or absence) of baseline Q waves and by reperfusion strategy received. They measured ST-segment resolution, an ECG marker of how well blood flow was restored to the heart muscle, and tracked a combined outcome of death, heart failure, cardiogenic shock, and repeat heart attack.
Baseline Q waves were present in 21.8% of patients. Compared with those who had Q waves, patients without them showed significantly better blood flow restoration and fewer adverse events at 30 days. Regardless of Q wave status, the pharmacoinvasive strategy was associated with better blood flow restoration than primary PCI, with the strongest one-year outcomes seen in patients without Q waves who received the pharmacoinvasive approach. These patterns were consistent across male and female patients.
These findings suggest that baseline Q wave status could help identify which STEMI patients stand to benefit most from an early pharmacoinvasive strategy, though the authors note these associations require further confirmation.
This study was led by Robert Kay, MD, MSc, under the supervision of Kevin Bainey, MD, MSc. The CVC team also included Yinggan (Gray) Zheng, MA, MEd; Eric Ly, BHK; Cynthia Westerhout, PhD; Tracy Temple, RN; Robert Welsh, MD; and Paul Armstrong, MD, alongside Josh Perka, BSc (University of Calgary) and Ajay Sidhu, BSc (University of Alberta).
