Reduction of QTD--A Novel Marker of Successful Reperfusion in NSTEMI. Pathophysiologic Insights by CMR

Defective recovery of QT dispersion due to no-reflow following acute interventional therapy in patients with ST-segment elevation myocardial infarction

Background

Previous studies have suggested that adequate myocardial reperfusion after percutaneous coronary intervention (PCI) can improve the inhomogeneity of myocardial repolarization. However, it remains unclear whether no-reflow (NR) following emergency PCI involves disadvantages related to ventricular repolarization indices. The present study aimed to determine the effect of NR on QT dispersion (QTd) in patients with ST-segment elevation myocardial infarction (STEMI) and to evaluate the prognostic value of the relative reduction of QTd on ventricular arrhythmia events (VAEs).

Methods

A prospective case-control study was conducted. According to the inclusion criteria, 275 patients with STEMI who underwent primary PCI treatment at the First People's Hospital of Anqing affiliated to Anhui Medical University from January 2020 to May 2023 were enrolled. According to whether NR occurred during PCI, these patients were divided into two groups: an NR group and a non-NR group. Subsequently, the QT intervals were measured before and at 12 hours after PCI. Afterward, the QTd, corrected QTd (QTcd), and the relative reduction of QTd and QTcd 12 hours pre- and postprocedure (ΔQTd-R and ΔQTcd-R, respectively) were calculated. Finally, multivariable logistic regression analysis was performed to predict the risk of VAE occurrence.

Results

In the non-NR group, there was a significant decrease from baseline in postprocedure QTd (48±17 vs. 73±22 ms; P=0.009) and QTcd (54±19 vs. 80±23 ms; P=0.01); in contrast, the NR group showed no significant difference in QTd (64±20 vs. 75±23 ms; P=0.58) or QTd (70±22 vs. 82±26 ms; P=0.45). Furthermore, the ΔQTd-R and ΔQTcd-R were both lower in the NR group than in the non-NR group (P<0.05); however, the rate of VAEs was higher in the NR group than in the non-NR group (15.2% vs. 6.2%; P=0.02). The multivariable logistic regression analysis results revealed that each increase of 12% in ΔQTcd-R was an independent predictor of VAEs (odds ratio: 0.547; 95% confidence interval: 0.228-0.976).

Conclusions

The NR phenomenon following primary PCI in patients with STEMI leads to the defective recovery of QTd and QTcd. Furthermore, ΔQTcd-R can be viewed as an effective indicator for evaluating the myocardial repolarization inhomogeneity, and short-term clinical outcomes.

QT interval Independently Predicts Mortality and Heart Failure in Patients with ST-Elevation Myocardial Infarction

OBJECTIVES

Heart-rate corrected QT (QTc) interval predicts cardiovascular mortality or all-cause mortality in the general population. Little is known about the best cut-off value of QTc interval for predicting clinical events in patients with ST-elevation myocardial infarction (STEMI).

METHODS

We enrolled 264 patients with STEMI who received measurement of QTc intervals at ER (QTc-ER), on day 2 (QTc-D2), and on day 3 (QTc-D3) of hospitalization. Clinical events, including all-cause death and readmission for heart failure, were followed for 2 years.

RESULTS

Prolonged QTc-ER, but not QTc-D2 or QTc-D3, well predicted clinical events with the best cut-off value of 445 ms. Patient with QTc-ER > 445 ms had lower left ventricular ejection fraction at baseline and at 6 months. Kaplan-Meier survival curves showed that the combination of QTc-ER > 445 ms and N-terminal pro-brain natriuretic peptide (NT-pro BNP) > 936 pg/mL was a strong predictor of clinical events (p<0.001). In multivariable Cox regression analysis, the independent predictors of death and heart failure were QTc-ER (p<0.001), log NT-proBNP (p<0.001), diabetes mellitus (p<0.001), history of stroke (p=0.001), and left ventricular end diastolic volume index (p<0.001).

CONCLUSION

QTc-ER > 445 ms independently predicts clinical events in STEMI, providing incremental prognostic value to established clinical predictors and NT-proBNP.