Association Between Early Q Waves and Reperfusion Success in Patients With ST-Segment–Elevation Myocardial Infarction Treated With Primary Percutaneous Coronary Intervention

Abstract

ST-segment-elevation myocardial infarction (STEMI) is treated with timely primary percutaneous coronary intervention (PCI) to improve the prognosis by reducing final infarct size and improving myocardial salvage. 1 In STEMI patients, cardiac magnetic resonance (CMR) has become an important method to quantify area at risk, 2-5 infarct size, 5,6 and myocardial salvage index.2,5,7 CMR does also allow for assessment of microvascular damage (microvascular obstruction [MVO]) within the infarct area. 8,9 Myocardial salvage index and MVO are both predictors for outcome in STEMI patients treated with primary PCI and therefore considered markers of successful reperfusion. 10A pathological Q wave (QW) in the ECG before reperfusion (early QW) is a frequent observation in patients presenting with STEMI. 11 The presence of QW is considered a surrogate for transmural infarction, whereas the absence of QW is interpreted as a sign of subendocardial infarction.12-15 However, previous studies have found transmural infarction in some patients Background-Pathological early Q waves (QW) are associated with adverse outcomes in patients with ST-segment-elevation myocardial infarction (STEMI). Primary percutaneous coronary intervention (PCI) may therefore be less beneficial in patients with QW than in patients without QW. Myocardial salvage index and microvascular obstruction (MVO) are markers for reperfusion success. Thus, to clarify the benefit from primary PCI in STEMI patients with QW, we examined the association between baseline QW and myocardial salvage index and MVO in STEMI patients treated with primary PCI. Methods and Results-The ECG was assessed before primary PCI for the presence of QW (early) in 515 STEMI patients.The patients underwent a cardiac magnetic resonance imaging scan at day 1 (interquartile range [IQR], 1-1) and again at day 92 (IQR,(89)(90)(91)(92)(93)(94)(95)(96). Early QW was observed in 108 (21%) patients and was related to smaller final myocardial salvage index ( and more extensive MVO than non-QW despite treatment within 12 hours after symptom onset. However, final myocardial salvage index in patients with QW was substantial, and patients with QW still benefit from primary PCI. 16,18,19 Furthermore, the presence of early QW in patients with STEMI treated with reperfusion (thrombolysis or primary PCI) is related to worse clinical outcome. 11,[20][21][22][23] Interestingly, the benefit from reperfusion with primary PCI compared with thrombolysis seems to be attenuated in patients with early QW. 24 It may therefore be speculated that patients with QW STEMI benefit to a lesser extent from primary PCI than non-QW. Evaluating the association between QW and myocardial salvage index and MVO may help to clarify the benefit from primary PCI in STEMI patients with baseline QW. However, to the best of our knowledge, there exist no data on the association between early QW and myocardial salvage index and MVO after primary PCI. Thus, the aim of this study was to evaluate the association between early QW and myocar...

Residual ST-segment elevation to predict long-term clinical and CMR-derived outcomes in STEMI

“…Lower percentage post-reperfusion ST resolution 8 , 27 – 29 and higher residual ST-segment elevation, either sum 30 or residual single-lead ST-deviation 29 , have been associated with worse short-term clinical outcomes after reperfused STEMI 31 . Also, Q waves (either on the presenting ECG or developing after STEMI) have also been associated with worse clinical outcomes 13 – 15 and more adverse early CMR-derived structural parameters 16 , 17 .…”

“…More recently it has also been associated with more severe structural consequences in cardiac magnetic resonance (CMR) performed soon after STEMI 11 , 12 . Presence of Q waves on the presenting ECG or its development after STEMI have also been associated with worse clinical outcomes 13 – 15 and more adverse early CMR-derived structural parameters 16 , 17 .…”

Clinical significance of R‐wave amplitude in lead V1 and inferobasal myocardial infarction in patients with inferior wall myocardial infarction

“…The LV infarcted size, expressed as a percentage of LV mass, can be computed using the modified Aldrich score = 3 × (0.6 (∑ST↑ II, III, aVF) + 2.0) + 3 × (1.5 (number of other leads with ST↑) − 0.4) (Clemmensen et al., 1991 ). The early Q wave before reperfusion defined as Q duration ≥40 ms and depth ≥25% of the R and the Sclarovsky–Birnbaum Ischemia Grade was recorded in lead III (Topal et al., 2017 ). The Sclarovsky–Birnbaum Ischemia Grading System (SB‐IG) is an electrocardiographic method evaluating the severity of ischemia based on QRS‐ST‐T changes, but inverted or biphasic T is excluded (Billgren et al., 2004 ).…”

“…In the context of STEMI, a pathological Q wave on the ECG prior to reperfusion is commonly noted. The prevalence of Q wave during the thrombolytic therapy era was between 33% and 53%, and during the percutaneous coronary intervention (PCI) era, it was between 21% and 72% (Andrews et al., 2000 ; Armstrong et al., 2009 ; Raitt et al., 1995 ; Topal et al., 2017 , 2020 ). Notably, in STEMI, an abnormal Q wave might not conclusively indicate irreversible myocardial damage.…”

“…It could signify intense, yet reversible, cellular ischemia or depict stunned and hibernating myocardium (Bateman et al., 1983 ; Sztajzel & Urban, 2000 ). Even though a baseline Q wave suggests a poor prognosis, STEMI patients with a Q wave still gain advantages from primary PCI (Topal et al., 2017 ), and effective reperfusion therapy can lead to Q‐wave regression or the return of R wave from hours to weeks post‐STEMI, hinting at recovered myocardial and improved left ventricular functions (Rijnierse et al., 2012 ; Sztajzel & Urban, 2000 ).…”