Occult etiologies of complete atrioventricular block: Report of two cases

AbstractIn patients presenting with complete atrioventricular (AV) block, the common causes are degeneration of the conduction system, acute myocardial infarction, congenital and metabolic disorders (such as azotemia). However, at times, no cause can be ascribed and the label congenital or degenerative is applied depending on the patient's age and the QRS complex width. We present two cases of patients with complete AV block, who were subsequently found to have rare etiologies – sarcoidosis (with isolated feature of AV block) and non-Hodgkin's lymphoma

Comparison of the spatial QRS-T angle derived from digital ECGs recorded using conventional electrode placement with that derived from Mason-Likar electrode position

Background: The spatial QRS-T angle is ideally derived from orthogonal leads. We compared the spatial QRS-T angle derived from orthogonal leads reconstructed from digital 12-lead ECGs and from digital Holter ECGs recorded with the Mason-Likar (M-L) electrode positions. Methods and results: Orthogonal leads were constructed by the inverse Dower method and used to calculate spatial QRS-T angle by (1) a vector method and (2) a net amplitude method, in 100 volunteers. Spatial QRS-T angles from standard and M-L ECGs differed significantly (57° ± 18° vs 48° ± 20° respectively using net amplitude method and 53° ± 28° vs 48° ± 23° respectively by vector method; p < 0.001). Difference in amplitudes in leads V4–V6 was also observed between Holter and standard ECGs, probably due to a difference in electrical potential at the central terminal. Conclusion: Mean spatial QRS-T angles derived from standard and M-L lead systems differed by 5°–9°. Though statistically significant, these differences may not be clinically significant

A pilot study comparing two sites for incision during pacemaker implantation and their influence on the scar

Objective: There are two most common incisions that are used during most pacemaker implantation procedures, with the first type of incision being inferior and parallel to the clavicle (Group C) and the second type of incision along the deltopectoral groove (Group D). We evaluated the scars resulting from the two types of incision to objectively evaluate the degree of superiority in cosmetic outcomes, between these two types of incisions. Methods: Seventy-six patients who underwent left pre-pectoral pacemaker insertion were evaluated, close to 6 months after the date of the pacemaker implantation, using a simple scoring system based on atrophy, contour and colour of the scar. The likelihood of reduced severity in scar scores were compared between the two groups and the number of patients with elevation or inversion of the scar and with keloid formation were quantified. Results: Seventy-six patients, with 47 belonging to the ‘Group C’ and 29 belonging to the ‘Group D’ were evaluated. The average length (C: 25 ± 2 mm; D: 24 ± 3 mm) and thickness (C: 25 ± 3 mm; D: 26 ± 2 mm) of the scars were not significantly different. The mean cumulative total scores in ‘Group C’ (1.98 ± 1.50) and ‘Group D’ (1.93 ± 1.31) were comparable. The odds ratio (OR) estimate showed that outcomes for atrophy (OR:0.73), contour (OR:0.53) and the cumulative total scores (OR:0.72) were also comparable. Conclusion: This pilot study showed that the deltopectoral groove incision as a site of incision is comparable to the infraclavicular incision. Keywords: Bradyarrhythmia, Surgical scar, Cardiac implantable electronic device

Choice of an alternative lead for QT interval measurement in serial ECGs when Lead II is not suitable for analysis

Introduction: Conventionally, QT interval is measured in lead II. There are no data to select an alternative lead for QT measurement when it cannot be measured in Lead II for any reason. Methods and results: We retrospectively analyzed ECGs from 1906 healthy volunteers from 41 phase I studies. QT interval was measured on the median beat in all 12 leads. The mean difference in QT interval between lead aVR and in Lead II was the least, followed by aVF, V5, V6 and V4; lead aVL had maximum difference. The T wave was flat (<0.1 mV) in Lead II in 6.9% of ECGs; it was also flat in 20% of these ECGs (1.4% of all ECGs) in Leads aVR, aVF and V5. Conclusions: When QT interval cannot be measured in Lead II, the best alternative leads are aVR, aVF, V5, V6 and V4 in that sequence. It differs maximally from that in Lead II in Lead aVL

Estimating Myocardial Infarction Size With a Simple Electrocardiographic Marker Score

© 2020 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley. Background: Myocardial infarction (MI) size is a key predictor of prognosis in post-MI patients. Cardiovascular magnetic resonance (CMR) is the gold standard test for MI quantification, but the ECG is less expensive and more widely available. We sought to quantify the relationship between ECG markers and cardiovascular magnetic resonance infarct size. Methods and Results: Patients with prior MI enrolled in the DETERMINE (Defibrillators to Reduce Risk by Magnetic Resonance Imaging Evaluation) and PRE-DETERMINE Trial and Registry were included. ECG leads were analyzed for markers of MI: Q waves, fragmented QRS, and T wave inversion. DETERMINE Score=number of leads with [Q waves×2]+[fragmented QRS]+[T wave inversion]. Left ventricular ejection fraction (LVEF) and infarct size as a percentage of left ventricular mass (MI%) were quantified by cardiovascular magnetic resonance. The Modified Selvester Score estimates MI size from 37 ECG criteria. In 551 patients (aged 62.1±10.9 years, 79% men, and LVEF=40.3±11.0%), MI% increased as the number of ECG markers increased (P\u3c0.001). By univariable linear regression, the DETERMINE Score (range 0–26) estimated MI% (R2=0.18, P\u3c0.001) with an accuracy approaching that of LVEF (R2=0.22, P\u3c0.001) and higher than the Modified Selvester Score (R2=0.09, P\u3c0.001). By multivariable linear regression, addition of the DETERMINE Score improved estimation of MI% over LVEF alone (P\u3c0.001) and over Modified Selvester Score alone (P\u3c0.001). Conclusions: In patients with prior MI, a simple ECG score estimates infarct size and improves infarct size estimation over LVEF alone. Because infarct size is a powerful prognostic indicator, the DETERMINE Score holds promise as a simple and inexpensive risk assessment tool

Validation of electrocardiographic criteria for identifying left ventricular dysfunction in patients with previous myocardial infarction

Background Eleven criteria correlating electrocardiogram (ECG) findings with reduced left ventricular ejection fraction (LVEF) have been previously published. These have not been compared head‐to‐head in a single study. We studied their value as a screening test to identify patients with reduced LVEF estimated by cardiac magnetic resonance (CMR) imaging. Methods ECGs and CMR from 548 patients (age 61 + 11 years, 79% male) with previous myocardial infarction (MI), from the DETERMINE and PRE‐DETERMINE studies, were analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each criterion for identifying patients with LVEF ≤ 30% and ≤ 40% were studied. A useful screening test should have high sensitivity and NPV. Results Mean LVEF was 40% (SD = 11%); 264 patients (48.2%) had LVEF ≤ 40%, and 96 patients (17.5%) had LVEF ≤ 30%. Six of 11 criteria were associated with a significant lower LVEF, but had poor sensitivity to identify LVEF ≤ 30% (range 2.1%–55.2%) or LVEF ≤ 40% (1.1%–51.1%); NPVs were good for LVEF ≤ 30% (range 82.8%–85.9%) but not for LVEF ≤ 40% (range 52.1%–60.6%). Goldberger's third criterion (RV4/SV4  124 ms + either Goldberger's third criterion or Goldberger's first criterion (SV1 or SV2 + RV5 or RV6 ≥ 3.5 mV) had high specificity (95.4%–100%) for LVEF ≤ 40%, although seen in only 48 (8.8%) patients; predictive values were similar on subgroup analysis. Conclusions None of the ECG criteria qualified as a good screening test. Three criteria had high specificity for LVEF ≤ 40%, although seen in < 9% of patients. Whether other ECG criteria can better identify LV dysfunction remains to be determined