A Practical Method for QTc Interval Measurement.

Objective The various formulae used for QT correction by heart rate (HR) require the execution of operations with the aid of calculators or applications. This study aimed to evaluate the performance of a simple rule for QTc estimation, comparing the measurements obtained with those provided by the commonly used equations of Bazett, Fridericia, Framingham, and Hodges. Methods We used the database of a previous observational study, which analyzed patients prospectively with acute pulmonary edema admitted in an emergency service. One hundred four patients were included for QTc assessment, of whom 86 patients underwent two ECG: one ECG <24h and other >24h after admission. Thus, a total of 190 ECGs were analyzed by two observers that manually measured QT and HR. QTc was obtained using the known formulae and the proposed equations: QTc = QT+2 (FC-60) for HR ≤ 90 bpm and QTc=QT+2(FC-60)-10 for HR>90 bpm. Results Bland-Altman plots show good agreement between the simple rule and Hodges equation, with a mean difference of -3,4, SD of 4.96 and 95% limits of agreement from -9,9 to 3.2. There was not a good agreement between the simple method and the other formulae. Conclusion The proposed method has good agreement with the measures of QTc by the equation of Hodges in the HR range of 40 to 130bpm in acutely ill patients. Our method may be a plausible option for quick QT correction in these subjects.

Brugada phenocopy: Mechanisms, diagnosis, and implications.

Brugada phenocopies are Brugada-like ECG patterns induced by reversible clinical conditions. Baranchuk and colleagues characterized this condition in 2012, and since then the phenomenon has been increasingly reported. It has the same pattern classification of Brugada syndrome (i.e., types 1 and 2), but differs substantially regarding etiology and prognosis. Awareness of Brugada phenocopies must be sought to help understanding the mechanisms of ion channel dysfunction and to avoid misdiagnosis and mistreatment of Brugada syndrome.

Transient triangular QRS-ST-T waveform with good outcome in a patient with left main coronary artery stenosis: A case report.

Triangular QRS-ST-T waveform, also known as "shark fin pattern", is an ECG presentation of ST segment elevation myocardial infarction with a unique wave composed by the QRS complex, the ST segment, and the T wave. It is associated with very poor prognosis and recently has been shown to be more common in patients with left main coronary artery (LMCA) involvement. Nevertheless, data supporting this correlation is scant. Herein we present a case of a patient with LMCA subtotal occlusion who developed a transient triangular QRS-ST-T waveform after an initial ECG had shown subendocardial ischemia. Electrocardiographic findings resolved spontaneously, and the patient was successfully treated without major complications. It is uncertain what caused the change between patterns.

Cardiac Hemodynamics Abnormalities Induced by Intermittent Left Bundle-branch Block: A Case Report.

The left bundle-branch block (LBBB) is related to worsening cardiac performance. We describe a case of a patient with an intermittent left bundle-branch block who underwent biventricular pacemaker implantation. We noted a detrimental effect on the performance of her left ventricle with the presence of the LBBB as compared to the performance after she underwent biventricular pacing or after reversal of LBBB (i.e., native rhythm with narrow QRS). Her LBBB was accompanied by increased isovolumetric contraction time, longer pre-ejection period, and increased myocardial performance index (i.e., the Tei index) compared to her sinus rhythm with a narrow QRS complex with or under biventricular pacing.