Impact of myocardial reperfusion status on QT dispersion after successful recanalization of the infarct-related artery in acute myocardial infarction

Prognostic value of infarct-related-lead Tpeak-Tend/QT ratio in patients with ST-segment elevation myocardial infarction

Tpeak-Tend/QT ratio (Tp-e/QT) in patients with ST-segment elevation myocardial infarction (STEMI) is reportedly associated with major adverse cardiac events (MACEs). However, Tp-e/QT measurement methods are controversial, and few studies have clarified the effect of different Tp-e/QT measures on prognosis. Our study is the first to investigate the advantages of the Tp-e/QT measured by infarct-related-lead method in predicting MACEs during hospitalization and long-term mortality in patients with STEMI. A total of 427 STEMI patients undergoing primary percutaneous coronary intervention (PCI) were included in this study. The Tp-e/QT before PCI was measured by traditional 12-lead method and infarct-related-lead method. Outcomes were tested using comparative statistics, logistic regression, receiver operating characteristic (ROC) curve and Kaplan-Meier survival analysis. There were 62 (14.5%) patients who had MACEs in-hospital. Logistic regression showed that the Tp-e/QT in infarct-related-lead was an independent predictor (p < 0.001). The area under the ROC curve (AUC) of the Tp-e/QT in infarct-related-lead was larger than that in the Tp-e/QT in traditional 12-lead (0.889 vs 0.741), and the optimal cutoff value was 0.32. The three-year survival rate of patients in the infarct-related-lead Tp-e/QT < 0.32 group was better than Tp-e/QT ≥ 0.32 group in Kaplan-Meier survival analysis (93.9 vs 87.0%). When stratified according to infarct-related arteries, the results showed that the common odds ratio of patients in Tp-e/QT ≥ 0.32 group occurred MACEs was 1.562, P = 0.038. The infarct-related-lead Tp-e/QT performed better than the traditional 12-lead Tp-e/QT in predicting poor prognosis.

Low Ankle-Brachial Index is Associated with Microvascular Coronary Obstruction After Primary PCI

Introduction

Percutaneous coronary intervention (PCI) has improved recanalization of infarct-related arteries (IRA); however, TIMI-III flow does not always mean an efficient myocardial reperfusion. Myocardial blush grade (MBG) is used as a predictor for coronary microvascular obstruction. We assessed the association between ankle-brachial index (ABI), a widely used method for diagnosis of peripheral arterial disease (PAD), and coronary microvascular obstruction (MVO) as detected by MBG after primary PCI.

Patients and Methods

The study included 335 patients with ST-elevation myocardial infarction who had primary PCI. History taking, clinical examination, laboratory assessment, ECG and Echocardiography were done for every participant. MBG was assessed for patients after PCI procedure. ABI for all participating patients was calculated.

Results

Two hundred and sixty-one patients fulfilled the inclusion criteria with mean age 58.8 ± 10.7 years, 84% were males. Sixty-one percent had anterior wall myocardial infarction. After primary PCI, despite achieving TIMI flow III in all study patients, only 37% had normal MBG. There was a statistically significant relationship between MBG and site of infarction, left ventricular ejection fraction and ABI. Low ABI was found to predict poor MBG.

Conclusion

Coronary artery disease (CAD) is well linked to PAD. MBG can be used to assess coronary MVO after primary PCI. Poor MBG is associated with low ABI. This could establish a relationship between PAD and coronary MVO after primary PCI.

Increased QT Dispersion Is Linked to Worse Outcomes in Patients Hospitalized for Out-of-Hospital Cardiac Arrest

Background The incidence and mortality of out-of-hospital cardiac arrest (OHCA) remains high, but predicting outcomes is challenging. Being able to better assess prognosis of hospitalized patients after return of spontaneous circulation would enable improved management of survival expectations. In this study, we assessed the predictive value of ECG indexes in hospitalized patients with OHCA. Methods and Results PR interval and QT interval corrected by the Bazett formula (QTc) for all leads were calculated from standard 12-lead ECGs 24 hours after return of spontaneous circulation in 93 patients who were hospitalized following OHCA. PR interval and QT and QTc duration did not differentiate OHCA survivors and nonsurvivors. However, QT and QTc dispersion was significantly increased in patients who died during hospitalization compared with survivors discharged from the hospital (P<0.01). Logistic regression indicated a strong association between increased QT dispersion and in-hospital mortality (P<0.0001; area under the curve, 0.8918 for QT dispersion and 0.8673 for QTc dispersion). Multinomial logistic regression indicated that the increase of QTc dispersion correlated with worse Cerebral Performance Category scores at discharge (P<0.001; likelihood ratio, 51.42). There was also significant correlation between dispersion measures and serum potassium at the time of measurement and between dispersion measures and cumulative epinephrine administration. No difference existed regarding the number of measurable leads. Conclusions Lesser QT and QTc dispersion at 24 hours after return of spontaneous circulation was significantly associated with survival and neurologic status at discharge. Routine evaluation of QT and QTc dispersion during hospitalization following return of spontaneous circulation might improve outcome prognostication for patients hospitalized for OHCA.

Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice

Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a challenge for the medical community due to the tragic outcomes in most cases. In the last two decades some ventricular repolarization (VR) markers have been found to be useful to predict malignant cardiac arrhythmias in several clinical conditions. The corrected QT, QT dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tp-e/QT have been studied and implemented in clinical practice for this purpose. These markers are obtained from 12 lead surface electrocardiogram. In this review we discuss how these markers have demonstrated to be effective to predict malignant arrhythmias in medical conditions such as long and short QT syndromes, Brugada syndrome, early repolarization syndrome, acute myocardial ischemia, heart failure, hypertension, diabetes mellitus, obesity and highly trained athletes. Also the main pathophysiological mechanisms that explain the arrhythmogenic predisposition in these diseases and the basis for the VR markers are discussed. However, the same results have not been found in all conditions. Further studies are needed to reach a global consensus in order to incorporate these VR parameters in risk stratification of these patients.

QT Dispersion after Thrombolytic Therapy

BACKGROUND

QT dispersion (QTd) is equal to longer QTc minus shorter QTc measured by 12-lead electrocardiogram (ECG). QTd reflects inhomogeneity in repolarization of ventricular myocardium and because of easy and fast measurement of QTd, it can be used to predict high-risk patients for dysrhythmia after Acute Myocardial Infarction (AMI).

OBJECTIVES

This study aimed to assess the effect of thrombolytic therapy on QTd before and 1 hour and 4 days after beginning of thrombolytic therapy.

PATIENTS AND METHODS

The patients with chest pain and ST Elevated Myocardial Infarction (STEMI) that underwent thrombolytic therapy were enrolled into this study. Streptokinase was the thrombolytic agent in all the patients. Standard 12-lead (ECG) was evaluated before beginning of thrombolytic therapy (QTd 1) and 1 hour (QTd2) and 4 days (QTd3) after thrombolytic therapy. First, ECG was magnified × 10 for exact calculation of QT and QTd. After all, the variables were compared using one-way analysis of variance (ANOVA). Besides, P ≤ 0.05 was considered as statistically significant.

RESULTS

This study was conducted on 160 patients. The results revealed no significant differences among QTd 1, QTd 2, and QTd 3 (P > 0.05). At inferior AMI, however, a significant difference was observed among QTd1, QTd2, and QTd3 (P = 0.031).

CONCLUSIONS

Thrombolytic therapy had no significant effects on QTd. Thus, thrombolytic therapy does not increase the risk of arrhythmia.