Utility of electrocardiogram to predict the occurrence of the no-reflow phenomenon in patients undergoing primary percutaneous coronary intervention (PPCI): a systematic review and meta-analysis

Background

The no-reflow phenomenon affects about one out of five patients undergoing Primary Percutaneous Coronary Intervention (PPCI). As the prolonged no-reflow phenomenon is linked with unfavorable outcomes, making early recognition is crucial for effective management and improved clinical outcomes in these patients. Our review study aimed to determine whether electrocardiogram (ECG) findings before PCI could serve as predictors for the occurrence of the no-reflow phenomenon.

Methods and materials

We systematically searched MEDLINE, Scopus, and Embase to identify relevant studies. The random-effect model using inverse variance and Mantel-Haenszel methods were used to pool the standardized mean differences (SMD) and odds ratios (OR), respectively.

Result

Sixteen eligible articles (1,473 cases and 4,264 controls) were included in this study. Based on our meta-analysis of baseline ECG findings, the no-reflow group compared to the control group significantly had a higher frequency of fragmented QRS complexes (fQRS) (OR (95% CI): 1.35 (0.32-2.38), P-value = 0.01), and Q-waves (OR (95% CI): 1.97 (1.01-2.94), P-value <0.001). Also, a longer QRS duration (QRSD) (SMD (95% CI): 0.72 (0.21, 1.23), p-value <0.001) and R wave peak time (RWPT) (SMD (95% CI): 1.36 (0.8, 1.93), P < 0.001) were seen in the no-reflow group. The two groups had no significant difference regarding P wave peak time (PWPT), and P wave maximum duration (Pmax) on baseline ECG.

Conclusion

Our findings suggest that prolonged QRSD, delayed RWPT, higher fQRS prevalence, and the presence of a Q wave on baseline ECG may predict the occurrence of the no-reflow phenomenon in patients undergoing PPCI.

Coronary No-Reflow after Primary Percutaneous Coronary Intervention-Current Knowledge on Pathophysiology, Diagnosis, Clinical Impact and Therapy

Coronary no-reflow (CNR) is a frequent phenomenon that develops in patients with ST-segment elevation myocardial infarction (STEMI) following reperfusion therapy. CNR is highly dynamic, develops gradually (over hours) and persists for days to weeks after reperfusion. Microvascular obstruction (MVO) developing as a consequence of myocardial ischemia, distal embolization and reperfusion-related injury is the main pathophysiological mechanism of CNR. The frequency of CNR or MVO after primary PCI differs widely depending on the sensitivity of the tools used for diagnosis and timing of examination. Coronary angiography is readily available and most convenient to diagnose CNR but it is highly conservative and underestimates the true frequency of CNR. Cardiac magnetic resonance (CMR) imaging is the most sensitive method to diagnose MVO and CNR that provides information on the presence, localization and extent of MVO. CMR imaging detects intramyocardial hemorrhage and accurately estimates the infarct size. MVO and CNR markedly negate the benefits of reperfusion therapy and contribute to poor clinical outcomes including adverse remodeling of left ventricle, worsening or new congestive heart failure and reduced survival. Despite extensive research and the use of therapies that target almost all known pathophysiological mechanisms of CNR, no therapy has been found that prevents or reverses CNR and provides consistent clinical benefit in patients with STEMI undergoing reperfusion. Currently, the prevention or alleviation of MVO and CNR remain unmet goals in the therapy of STEMI that continue to be under intense research.

Neutrophil extracellular traps in ischemia-reperfusion injury-induced myocardial no-reflow: therapeutic potential of DNase-based reperfusion strategy

Emerging evidence suggests a potential role of neutrophil extracellular traps (NETs) in linking sterile inflammation and thrombosis. We hypothesized that NETs would be induced during myocardial ischemia-reperfusion (I/R), and NET-mediated microthrombosis may contribute to myocardial "no-reflow". Male Wistar rats were randomly divided into I/R control, DNase (DNase I, 20 μg/rat), recombinant tissue-type plasminogen activator (rt-PA, 420 μg/rat), DNase + rt-PA, and sham control groups after 45-min myocardial ischemia. In situ NET formation, the anatomic "no re-flow" area, and infarct size were evaluated immediately after 3 h of reperfusion. Long-term left ventricular (LV) functional and histological analyses were performed 45 days after operation. Compared with the I/R controls, the DNase + rt-PA group exhibited reduced NET density [8.38 ± 1.98 vs. 26.86 ± 3.07 (per 200 × field), P < 0.001] and "no-flow" area (15.22 ± 0.06 vs. 34.6 ± 0.05%, P < 0.05) in the ischemic region, as well as reduced infarct size (38.39 ± 0.05 vs. 71.00 ± 0.03%, P < 0.001). Additionally, compared with the I/R controls, DNase + rt-PA treatment significantly ameliorated I/R injury-induced LV remodeling (LV ejection fraction: 64.22 ± 3.37 vs. 33.81 ± 2.98%, P < 0.05; LV maximal slope of the LV systolic pressure increment: 3,785 ± 216 vs. 2,596 ± 299 mmHg/s, P < 0.05). The beneficial effect was not observed in rats treated with DNase I or rt-PA alone. Our study provides evidence for the existence of NETs in I/R-challenged myocardium and confirms the long-term benefit of a novel DNase-based reperfusion strategy (DNase I + rt-PA), which might be a promising option for the treatment of myocardial I/R injury and coronary no-reflow.