Diagnostic value of the cardiac electrical biomarker,a novel ECG marker indicating myocardial injury,in patients with symptoms suggestive of non‐ST‐elevation myocardial infarction

Background

The cardiac electrical biomarker (CEB) is a novel electrocardiographic (ECG) marker quantifying the dipolar activity of the heart with higher levels indicating myocardial injury.

Methods

We prospectively enrolled 1097 patients presenting with suspected non‐ST‐elevation myocardial infarction (NSTEMI) to the emergency department (ED). Digital 12‐lead ECGs were recorded at presentation and the CEB values were calculated in a blinded fashion. The final diagnosis was adjudicated by two independent cardiologists. The prognostic endpoint was all‐cause mortality during 2 years of follow‐up.

Results

NSTEMI was the final diagnosis in 14% of patients. CEB levels were higher in patients with NSTEMI compared to other causes of chest pain (median 44 (IQR 21–98) vs. 30 (IQR 16–61), p < .001). A weak but significant correlation between levels of high‐sensitivity cardiac troponin T (hs‐cTnT) at admission to the ED and the CEB was found (r = .23, p < .001). The use of the CEB in addition to conventional ECG criteria improved the diagnostic accuracy for the diagnosis of NSTEMI as quantified by the area under the receiver operating characteristics curve from 0.66 to 0.71 (p < .001) and the sensitivity improved from 43% to 79% (p < .001).

Conclusion

In conclusion, the CEB, an ECG marker of myocardial injury, significantly improves the accuracy and sensitivity of the ECG for the diagnosis of NSTEMI.

     

Coarse fibrillatory waves in atrial fibrillation predict success of electrical cardioversion

Background

To determine whether the presence of “coarse” fibrillatory waves (Fw) seen on surface ECGs of patients with persistent atrial fibrillation (AF) predict maintenance of sinus rhythm (SR) at 6 weeks after electrical cardioversion (ECV).

Methods

Preprocedure ECGs from 94 consecutive patients with persistent AF scheduled to undergo ECV at a single centre were classified as having coarse Fw (≥0.1 mV) or fine Fw (<0.1 mV) in leads II or V₁. The primary outcome was ECG rhythm at 6‐week clinical follow‐up. Demographic and echocardiographic data were also collected.

Results

Thirty‐two patient ECGs (34%) had coarse Fw on baseline ECG in either or both leads II or V₁ with no significant differences in baseline demographics compared to those patients with fine Fw. At 6 weeks post‐ECV, in the coarse Fw group 72% of patients maintained SR vs. 42% in the fine Fw group (χ², p = .006) with the odds ratio (OR) of maintaining SR at 6 weeks in the presence of coarse Fw being 3.5 (95% CI: 1.4–8.9, p = .007). Across the overall study population, there were no other significant univariate predictors of SR at 6 weeks post‐ECV.

Conclusion

Classifying persistent AF using the maximal Fw amplitude on a surface ECG is a simple and reproducible method of predicting medium‐term success of ECV, independent of traditional risk factors.

     

Ranolazine reduces repolarization heterogeneity in symptomatic patients with diabetes and non–flow‐limiting coronary artery stenosis

Background

Experimental evidence suggests that ranolazine decreases susceptibility to ischemia‐induced arrhythmias independent of effects on coronary artery blood flow.

Objective

In symptomatic diabetic patients with non–flow‐limiting coronary artery stenosis with diffuse atherosclerosis and/or microvascular dysfunction, we explored whether ranolazine reduces T‐wave heterogeneity (TWH), an electrocardiographic (ECG) marker of arrhythmogenic repolarization abnormalities shown to predict sudden cardiac death.

Methods

We studied all 16 patients with analyzable ECG recordings during rest and exercise tolerance testing before and after 4 weeks of ranolazine in the double‐blind, crossover, placebo‐controlled RAND‐CFR trial (NCT01754259). TWH was quantified without knowledge of treatment assignment by second central moment analysis, which assesses the interlead splay of T waves in precordial leads about a mean waveform. Myocardial blood flow (MBF) was measured by positron emission tomography.

Results

At baseline, prior to randomization, TWH during rest was 54 ± 7 μV and was not altered following placebo (47 ± 6 μV, p = .47) but was reduced by 28% (to 39 ± 5 μV, p = .002) after ranolazine. Ranolazine did not increase MBF at rest. Exercise increased TWH after placebo by 49% (to 70 ± 8 μV, p = .03). Ranolazine did not reduce TWH during exercise (to 75 ± 16 μV), and there were no differences among the groups (p = .95, ANOVA). TWH was not correlated with MBF at rest before (r² = .07, p = .36) or after ranolazine (r² = .23, p = .06).

Conclusions

In symptomatic diabetic patients with non‐flow‐limiting coronary artery stenosis with diffuse atherosclerosis and/or microvascular dysfunction, ranolazine reduced TWH at rest but not during exercise. Reduction in repolarization abnormalities appears to be independent of alterations in MBF.

     

S‐R difference in V1‐V2 is a novel criterion for differentiating the left from right ventricular outflow tract arrhythmias

Aim

The correct estimation of the VA origin as RVOT or LVOT results in reduced ablation duration reduced radiation exposure and decreased number of vascular access. In our study, we aimed to detect the predictive value of S‐R difference in V1‐V2 for differentiating the left from right ventricular outflow tract arrhythmias.

Methods

We included 123 patients with symptomatic frequent premature ventricular outflow tract contractions who underwent successful catheter ablation (70 male, 53 female; mean age 46.2 ± 13.9 years, 61 RVOT, 62 LVOT origins). S‐R difference in V1‐V2 was calculated with this formula on the 12‐lead surface ECG: (V1S + V2S) – (V1R + V2R). Conventional ablation was performed in 101 (82.1%) patients, CARTO electroanatomic mapping system was used in 22 (17.9%) patients.

Results

V1‐2 SRd was found to be significantly lower for LVOT origins than RVOT origins (p < .001). The cutoff value of V1‐2 SRd obtained by ROC curve analysis was 1.625 mV for prediction of RVOT origin (sensitivity: 95.1%, specificity: 85.5%, positive predictive value: 86.5%, negative predictive value: 94.5%). The area under the curve (AUC) was 0.929 (p < .001).

Conclusion

S‐R difference in V1‐V2 is a novel and simple electrocardiographic criterion for accurately differentiating RVOT from LVOT sites of ventricular arrhythmia origins. The use of this simple ECG measurement could improve the accuracy of OTVA localization, could be beneficial for decreasing ablation duration and radiation exposure. Further studies with larger patient population are needed to verify the results of this study.

     

Use of fragmented QRS in prognosticating clinical deterioration and mortality in pulmonary embolism: A meta‐analysis

Background

Fragmented QRS (fQRS) on electrocardiography is potentially valuable in prognosticating acute pulmonary embolism (PE). ECG is one of the first tests performed in the emergency department, quickly interpretable, noninvasive, inexpensive, and available in remote areas. We aimed to review fQRS's role in PE prognostication.

Methods

We searched MEDLINE, EMBASE, Google Scholar, Web of Science, abstracts, conference proceedings, and reference lists until October 2017. Eligible studies used fQRS to prognosticate patients for the main outcomes of death and clinical deterioration or escalation of therapy. Two authors independently selected studies, with disagreement resolved by consensus. Ad hoc piloted forms were used to extract data and assess risk of bias. We used a random‐effects model to pool relevant data in meta‐analysis with odds ratios (OR) and 95% confidence intervals (CI), while all other data were synthesized qualitatively. Statistical heterogeneity was assessed using the I² index.

Results

We included five studies (1,165 patients). There was complete agreement in study selection. fQRS significantly predicted in‐hospital mortality (OR [95% CI], 2.92 [1.73–4.91]; p < .001), cardiogenic shock (OR [95% CI], 4.71 [1.61–13.70]; p = .005), and total mortality at 2‐year follow‐up (OR [95% CI], 4.42 [2.57–7.60]; p < .001). Adjusted analyses were generally consistent with these results.

Conclusion

Although few studies have explored the current study's question, they showed that fQRS is potentially valuable in PE prognostication. fQRS should be considered as an entry, along with other clinical and ECG findings, in a PE risk score.

     

Comparison of the predictive accuracy of four different ECG algorithms in identification of true ablation site for the idiopathic right ventricular outflow tract tachycardias

Background

We aimed to investigate the accuracy of four algorithms in prediction of right ventricular outflow tract (RVOT) tachycardias in patients who successfully underwent radiofrequency catheter ablation.

Methods

Four algorithms; two with easy‐applicability and having a memorable design (Dixit and Joshi), and two with more complex and detailed design (Ito and Zhang) were compared according to the predictive accuracy.

Results

Among 99 patients (mean age 36.5 ± 8.5 years, 39.4% male), there were 51 (51.5%) septal‐located and 48 (48.5%) free‐wall located RVOT tachycardia. Comparison of the predictive accuracy of the algorithms showed that Zhang (91.9%) was the best algorithm for prediction of either septal or free‐wall located tachycardia. The second best algorithm was the Ito (77.7%) compared to Dixit (75.8%) and Joshi (70.7%).

Conclusion

In patients with RVOT tachycardia, algorithms with a detailed design may predict the arrhythmia location better than the easy‐applicable algorithms.

     

Impact of ST‐segment resolution on clinical outcome in patients with ST‐segment elevation myocardial infarction and preserved left ventricular function

Background

Patients with successful reperfusion and preserved left ventricular ejection fraction (LVEF) after ST‐segment myocardial infarction (STEMI)have always been thought to have low risk for adverse events. Great interest is focused on finding simple, noninvasive tools to refine risk stratification among them.

Objectives

We hypothesized that degree of ST‐segment resolution (STR) after STEMI can identify high‐risk group among patients with LVEF ≥ 50% following STEMI.

Methods

During the period from January to July 2017, patients with successful reperfusion of STEMI and LVEF ≥ 50% were prospectively included. Patients were divided into two groups based on the percent of ST segment resolution using single lead STR method; group I (complete STR ≥ 70%) and group II (partial STR 50%–70%). The endpoint was a composite of cardiovascular mortality, re‐hospitalization for heart failure and urgent revascularization at 30‐day.

Results

After exclusion, 110 patients were left for final analysis. No significant differences in all baseline characteristics were found between both groups. The primary endpoint occurred in seven patients (12.7%) of group I versus 17 patients (30.9%) of group II (Relative risk = 2.43, 95%CI = 1.1–5.4, p = 0.021) driven by a significant reduction in rates of re‐hospitalization due to heart failure. A multivariate logistic regression analysis showed incomplete STR to be a significant independent predictor for 30‐dayMACEs (OR 3.25, 95% CI1.2–8.83, p = 0.02) even after adjustment for location of infarction.

Conclusion

Complete STR predicts 30‐day outcome in patients with preserved LVEF following successful reperfusion of STEMI.

     

Prognostic value of positive T wave in lead aVR in patients with non‐ST segment myocardial infarction

Background

Lead aVR provides prognostic information in various settings in patients with ischemia. We aim to investigate the role of a positive T wave in lead aVR in non‐ST segment myocardial infarction (NSTEMI).

Methods

In a prospective cohort study, we included 400 patients with NSTEMI. Presentation electrocardiogram (ECG) was investigated for presence of a positive T wave as well as ST segment elevation (STE) in aVR and study variables were compared. Predictors of primary outcome defined as hospital major adverse cardiovascular events (MACE) and secondary outcome, defined as three‐vessel coronary disease and/or left main coronary artery stenosis (3VD/LMCA) stenosis in angiography, were determined in multivariate logistic regression analysis.

Results

Patients with a positive T wave in aVR were significantly older and were more likely to be female. Left ventricular ejection fraction was significantly lower in patients of positive T group. Positive T group was more likely to have 3VD/LMCA stenosis (58.3% vs. 19.8%, p < .001). The prevalence of a positive T wave in aVR was significantly higher in MACE group (54.9 % vs. 24.8%, p < .001). However, in multivariate analysis, it was not an independent predictor of MACE (OR: 1.083 95% CI: [0.496–2.365], p: .841). Though, it was independently associated with presence of 3VD/LMCA stenosis (OR: 3.747 95% CI: [2.058–6.822], p < .001).

Conclusion

Though positive T wave in lead aVR was more common in patients with MACE; it was not an independent predictor. Additionally, a positive T wave in aVR was an independent predictor of 3VD/LMCA stenosis in NSTEMI.

     

Unshielded magnetocardiography: Repeatability and reproducibility of automatically estimated ventricular repolarization parameters in 204 healthy subjects

Background

Magnetocardiographic mapping (MCG) provides quantitative assessment of the magnetic field (MF) induced by cardiac ionic currents, is more sensitive to tangential currents, and measures vortex currents undetectable by ECG, with higher reported sensitivity of MCG ventricular repolarization (VR) parameters for earlier detection of acute myocardial ischemia. Aims of this study were to validate the feasibility of in‐hospital unshielded MCG and to assess repeatability and reproducibility of quantitative VR parameters, considering also possible gender‐ and age‐related variability.

Methods

MCG of 204 healthy subjects [114 males—mean age 43.4 ± 17.3 and 90 females—mean age 40.2 ± 15.7] was retrospectively analyzed, with a patented proprietary software automatically estimating twelve VR parameters derived from the analysis of the dynamics of the T‐wave MF extrema (five parameters) and from the inverse solution with the effective magnetic dipole model giving the effective magnetic vector components (seven parameters). MCG repeatability was calculated as coefficient of variation (CV) ±standard error of the mean (SEM). Reproducibility was assessed as intraclass correlation coefficient (ICC).

Results

The repeatability of all MCG parameters was 16 ± 1.2 (%) (average CV ± SEM). Optimal (ICC > 0.7) reproducibility was found for 11/12 parameters (mean values) and in 8/12 parameters (single values). No significant gender‐related difference was observed; six parameters showed a strong/moderate correlation with age.

Conclusion

Reliable MCG can be performed into an unshielded hospital ambulatory, with repeatability and reproducibility of quantitative assessment of VR adequate for clinical purposes. Wider clinical use is foreseen with the development of multichannel optical magnetometry.

     

Genotype–phenotype relationship and risk stratification in loss‐of‐function SCN5A mutation carriers

Introduction

Loss‐of‐function (LoF) mutations in the SCN5A gene cause multiple phenotypes including Brugada Syndrome (BrS) and a diffuse cardiac conduction defect. Markers of increased risk for sudden cardiac death (SCD) in LoF SCN5A mutation carriers are ill defined. We hypothesized that late potentials and fragmented QRS would be more prevalent in SCN5A mutation carriers compared to SCN5A‐negative BrS patients and evaluated risk markers for SCD in SCN5A mutation carriers.

Methods

We included all SCN5A loss‐of‐function mutation carriers and SCN5A‐negative BrS patients from our center. A combined arrhythmic endpoint was defined as appropriate ICD shock or SCD.

Results

Late potentials were more prevalent in 79 SCN5A mutation carriers compared to 39 SCN5A‐negative BrS patients (66% versus 44%, p = .021), while there was no difference in the prevalence of fragmented QRS. PR interval prolongation was the only parameter that predicted the presence of a SCN5A mutation in BrS (OR 1.08; p < .001). Four SCN5A mutation carriers, of whom three did not have a diagnostic type 1 ECG either spontaneously or after provocation with a sodium channel blocker, reached the combined arrhythmic endpoint during a follow‐up of 44 ± 52 months resulting in an annual incidence rate of 1.37%.

Conclusion

LP were more frequently observed in SCN5A mutation carriers, while fQRS was not. In SCN5A mutation carriers, the annual incidence rate of SCD was non‐negligible, even in the absence of a spontaneous or induced type 1 ECG. Therefore, proper follow‐up of SCN5A mutation carriers without Brugada syndrome phenotype is warranted.

     

Baseline fragmented QRS increases the risk of major arrhythmic events in hypertrophic cardiomyopathy: Systematic review and meta‐analysis

Background

Fragmented QRS reflects disturbances in the myocardium predisposing the heart to ventricular tachyarrhythmias. Recent studies suggest that fragmented QRS (fQRS) is associated with worse major arrhythmic events in hypertrophic cardiomyopathy (HCM). However, a systematic review and meta‐analysis of the literature has not been done. We assessed the association between fQRS and major arrhythmic events in hypertrophic cardiomyopathy by a systematic review of the literature and a meta‐analysis.

Methods

We comprehensively searched the databases of MEDLINE and EMBASE from inception to May 2017. Included studies were published prospective or retrospective cohort studies that compared major arrhythmic events (sustained ventricular tachycardia, sudden cardiac arrest, or sudden cardiac death) in HCM with fQRS versus non‐fQRS. Data from each study were combined using the random‐effects, generic inverse variance method of DerSimonian and Laird to calculate risk ratios and 95% confidence intervals.

Results

Five studies from January 2013 to May 2017 were included in this meta‐analysis involving 673 subjects with HCM (205 fQRS and 468 non‐fQRS). Fragmented QRS was associated with major arrhythmic events (pooled risk ratio = 7.29, 95% confidence interval: 4.00–13.29, p < .01, I² = 0%).

Conclusion

Baseline fQRS increased major arrhythmic events up to sevenfold. Our study suggests that fQRS could be an important tool for risk assessment in patients with HCM.

     

Prognostic value of T‐wave morphology parameters in coronary artery disease in current treatment era

Background

The prognostic value of T‐wave morphology parameters in coronary artery disease in the current treatment era is not well established.

Methods

The Innovation to reduce Cardiovascular Complications of Diabetes at the Intersection (ARTEMIS) study included 1,946 patients with angiographically verified coronary artery disease (CAD). The study patients underwent thorough examinations including 12‐lead digital electrocardiogram (ECG) at baseline.

Results

During a follow‐up period of 73 ± 22 months, a total of 201 (10.3%) patients died. Of the study patients, 95 (4.9%) experienced cardiac death (CD) consisting of 44 (2.3%) sudden cardiac deaths (SCD) and 51 (2.6%) nonsudden cardiac deaths (NSCD), and 106 (5.4%) patients experienced noncardiac death (NCD). T‐wave morphology dispersion (TMD), T‐wave area dispersion (TWAD), and total cosine R‐to‐T (TCRT) had a significant association with CD even after adjustment with relevant clinical risk markers in the Cox regression analysis (multivariate HRs: 1.015, 95% CI 1.007–1.023, p = .0003; 0.474, 95% CI 0.305–0.737, p = .0009; 0.598, 95% CI 0.412–0.866, p = .006, respectively). When including these parameters to the clinical risk model for CD, the C‐index increased from 0.810 to 0.823 improving the discrimination significantly (integrated discrimination index [IDI] = 0.0118, 95% CI 0.0028–0.0208, p = .01). These parameters were more closely associated with NSCD (multivariate p‐values from .016 to .001) than with SCD (univariate/multivariate p‐values for TMD .015/.197 and for TCRT .012/.43).

Conclusion

T‐wave morphology parameters describing repolarization heterogeneity improve the predictive power of the clinical risk model for CD in patients with CAD in the current treatment era.

     

The analysis of the parameters of 24‐hr ECG Holter monitoring in patients with blood neoplasms undergoing high‐dose chemotherapy and stem cell transplantation

Background

Hematopoietic stem cell transplantation (HSCT) is a widely used procedure in the treatment of malignant diseases, including blood neoplasms and has increased survival in hematological diseases. The aim of the study was to analyze parameters of 24‐hr ECG monitoring in patients with selected blood neoplasms in whom the procedure of hematopoietic stem cell transplantation was performed.

Methods

The study group consisted of 64 adults diagnosed with hematologic cancer qualified for HSCT with the previous high dose chemotherapy (HDC). In all patients 24‐hr Holter monitoring was carried out twice. First examination took place prior to the HSCT procedure, and the second after finishing the procedure of HSCT.

Results

The minimal and mean heart rate (HR min and HR max) from 24‐hr ECG recording was statistically significantly higher after the transplantation in comparison with the first test. The number of premature ventricular complexes (PVCs) was higher in the test after HSCT. In the second examination there was significantly higher percentage of premature ventricular complexes, incidents of tachycardia, and Mobitz type 1 second degree atrioventricular block. In regression analysis, in a group of patients with blood neoplasms after HSCT and HDC, administration of cyclophosphamide, fludarabine and total body irradiation were independent risk factors for electrocardiographic abnormalities in 24‐hr Holter monitoring, that is, the increase in HR min, HR mean and PVCs.

Conclusion

In patients with blood neoplasms undergoing HSCT more electrocardiographic abnormalities may be found after this procedure in comparison with the 24‐hr Holter monitoring before transplantation.

     

The effect of head‐up tilt upon markers of heart rate variability in patients with atrial fibrillation

Background

Heart rate variability (HRV) analysis is uncommonly undertaken in patients with atrial fibrillation (AF) due to an assumption that ventricular response is random. We sought to determine the effects of head‐up tilt (HUT), a stimulus known to elicit an autonomic response, on HRV in patients with AF; we contrasted the findings with those of patients in sinus rhythm (SR).

Methods

Consecutive, clinically indicated tilt tests were examined for 207 patients: 176 in SR, 31 in AF. Patients in AF were compared to an age‐matched SR cohort (n = 69). Five minute windows immediately before and after tilting were analyzed using time‐domain, frequency‐domain and nonlinear HRV parameters. Continuous, noninvasive assessment of blood pressure, heart rate and stroke volume were available in the majority of patients.

Results

There were significant differences at baseline in all HRV parameters between AF and age matched SR. HUT produced significant hemodynamic changes, regardless of cardiac rhythm. Coincident with these hemodynamic changes, patients in AF had a significant increase in median [quartile 1, 2] DFA‐α2 (+0.14 [?0.03, 0.32], p < .005) and a decrease in sample entropy (?0.17 [?0.50, ?0.01], p < .005).

Conclusion

In the SR cohort, increasing age was associated with fewer HRV changes on tilting. Patients with AF had blunted HRV responses to tilting, mirroring those seen in an age matched SR group. It is feasible to measure HRV in patients with AF and the changes observed on HUT are comparable to those seen in patients in sinus rhythm.

     

Baseline fragmented QRS increases the risk of major arrhythmic events in Brugada syndrome: Systematic review and meta‐analysis

Background

Fragmented QRS reflects disturbances in the myocardium predisposing the heart to ventricular tachyarrhythmias. Recent studies suggest that fragmented QRS (fQRS) is associated with major arrhythmic events in Brugada syndrome. However, a systematic review and meta‐analysis of the literature has not been done. We assessed the association between fQRS and major arrhythmic events in Brugada syndrome by a systematic review of the literature and a meta‐analysis.

Methods

We comprehensively searched the databases of MEDLINE and EMBASE from inception to May 2017. Included studies were published prospective or retrospective cohort studies that compared major arrhythmic events (ventricular fibrillation, sustained ventricular tachycardia, sudden cardiac arrest, or sudden cardiac death) in Brugada syndrome with fQRS versus normal QRS. Data from each study were combined using the random‐effects, generic inverse variance method of DerSimonian and Laird to calculate risk ratios and 95% confidence intervals.

Results

Nine studies from January 2012 to May 2017 were included in this meta‐analysis involving 2,360 subjects with Brugada syndrome (550 fQRS and 1,810 non‐fQRS). Fragmented QRS was associated with major arrhythmic events (pooled risk ratio =3.36, 95% confidence interval: 2.09‐5.38, p < .001, I² = 50.9%) as well as fatal arrhythmia (pooled risk ratio =3.09, 95% confidence interval: 1.40‐6.86, p = .005, I² = 69.7%).

Conclusions

Baseline fQRS increased major arrhythmic events up to 3‐fold. Our study suggests that fQRS could be an important tool for risk assessment in patients with Brugada syndrome.

     

Ultra‐short heart rate variability recording reliability: The effect of controlled paced breathing

Background

Recent studies have reported that Heart Rate Variability (HRV) indices remain reliable even during recordings shorter than 5 min, suggesting the ultra‐short recording method as a valuable tool for autonomic assessment. However, the minimum time‐epoch to obtain a reliable record for all HRV domains (time, frequency, and Poincare geometric measures), as well as the effect of respiratory rate on the reliability of these indices remains unknown.

Methods

Twenty volunteers had their HRV recorded in a seated position during spontaneous and controlled respiratory rhythms. HRV intervals with 1, 2, and 3 min were correlated with the gold standard period (6‐min duration) and the mean values of all indices were compared in the two respiratory rhythm conditions.

Results

rMSSD and SD1 were more reliable for recordings with ultra‐short duration at all time intervals (r values from 0.764 to 0.950, p < 0.05) for spontaneous breathing condition, whereas the other indices require longer recording time to obtain reliable values. The controlled breathing rhythm evokes stronger r values for time domain indices (r values from 0.83 to 0.99, p < 0.05 for rMSSD), but impairs the mean values replicability of domains across most time intervals. Although the use of standardized breathing increases the correlations coefficients, all HRV indices showed an increase in mean values (t values from 3.79 to 14.94, p < 0.001) except the RR and HF that presented a decrease (t = 4.14 and 5.96, p < 0.0001).

Conclusion

Our results indicate that proper ultra‐short‐term recording method can provide a quick and reliable source of cardiac autonomic nervous system assessment.

     

A “Jail Escape Technique” (JET) for distal side branch wiring during provisional stenting: Feasibility and first‐in‐man study

Objective

To evaluate the feasibility of a novel technique for achieving distal SB access and improve strut apposition during provisional stenting.

Background

While distal rewiring and stent expansion toward the side branch (SB) are associated with better results during provisional stenting of coronary artery bifurcation lesions, these techniques are technically challenging and often leave unopposed struts near the carina.

Methods

The “Jail Escape Technique” (JET) is performed by passing the proximal tip of the SB wire between the main vessel (MV) stent struts and balloon before implantation, allowing the MV stent to push the SB wire against the distal part of the carina. The MV stent can then be deployed without jailing the SB wire. Distal SB access and strut distribution at the carina were tested in phantom and swine models. Stent distortion, dislodgement forces, and material damage were evaluated with tensile testing. Human feasibility was then tested on 32 patients.

Results

Preclinical testing demonstrated that the SB wire was located at the most distal part of the carina and no strut malapposition at the carina was present after balloon inflation. Stent distortion, dislodgement forces, or material damage were not affected. JET was successfully performed in 30 of 32 patients. No major adverse cardiovascular events occurred in any patient at 6‐month follow‐up.

Conclusion

The “JET” enables distal SB access and eliminates strut malapposition at the carina. Further studies with larger numbers of patients are needed to further investigate this technique.

     

Efficacy and safety of intravenous vernakalant for the rapid conversion of recent‐onset atrial fibrillation: A meta‐analysis

Background

Atrial fibrillation is a common cardiac arrhythmia with increasing prevalence in the aging population. It is a major cause of emergency department visits worldwide. Vernakalant, a relatively new antiarrhythmic drug with selectively preferential effects on the atrial tissue is currently used in many European countries for the termination of recent‐onset atrial fibrillation. Presently, the drug is still not approved by the United States Food and Drug Administration due to safety concerns. We evaluate the efficacy and safety of vernakalant for the conversion of recent‐onset atrial fibrillation or atrial flutter into normal sinus rhythm (NSR).

Methods

PubMed/MEDLINE (1993–2017), the Cochrane Central Register of Controlled Trials (2000–2017), and reference lists of relevant articles were searched for randomized controlled trials (RCTs) comparing vernakalant to a control drug and extracted subsequently.

Results

Nine RCTs were identified and included in the meta‐analysis. Pooled analysis of events extracted for a total of 1421 patients with recent‐onset atrial fibrillation showed a statistically significant increase in cardioversion within 90 minutes from drug infusion (Relative Risk [RR], 6.61; 95% Confidence Interval [CI], 2.78 – 15.71; p < .00001). In terms of adverse events, vernakalant was considered safe in comparison to control drugs (RR, 0.80; 95% CI, 0.61–1.05; p = .11).

Conclusion

Vernakalant is effective for rapid conversion of recent‐onset atrial fibrillation into NSR. However, although it showed a safe profile in terms of side effects in this analysis, we are still hesitant about this conclusion and few safety issues should be addressed within specific patients’ subgroups.

     

Clinical aspects of the three major genetic forms of long QT syndrome (LQT1, LQT2, LQT3)

Background

A comprehensive report on the clinical course of the three major genotypes of the long QT syndrome (LQTS) in a large U.S. patient cohort is lacking.

Methods

Our study consisted of 1,923 U.S. subjects from the Rochester‐based LQTS Registry with genotype‐positive LQT1 (n = 879), LQT2 (n = 807), and LQT3 (n = 237). We evaluated the risk of a first cardiac event (syncope, aborted cardiac arrest, or sudden cardiac death, whichever occurred first) from birth through age 50 years. Cox proportional hazards regression models incorporating clinical covariates were used to assess genotype‐specific risk of cardiac events.

Results

For all three genotypes, the cumulative probability of a first cardiac event increased most markedly during adolescence. Multivariate analysis identified proband status and QTc > 500 ms as predictors of cardiac events in all three genotypes, and males <14 years and females >14 years as predictors of cardiac events in LQT1 and LQT2 only. Beta‐blockers significantly reduced the risk of cardiac events in LQT1 (HR: 0.49, p = .002) and LQT2 patients (HR: 0.48, p = .001). A trend toward beta‐blocker benefit in reducing cardiac events was found in LQT3 females (HR: 0.32, p = .078), but not in LQT3 males (HR: 1.37, p = .611).

Conclusion

Risk factors and outcomes in LQTS patients varied by genotype. In all three genotypes, proband status and prolonged QTc were risk factors for cardiac events. Younger males and older females experienced increased risk in LQT1 and LQT2 only. Beta‐blockers were most effective in reducing cardiac events in LQT1 and LQT2, with a potential benefit in LQT3 females.

     

Is myocardial repolarization duration associated with repolarization heterogeneity?

Background

Dispersion of repolarization is theorized as one mechanism by which myocardial repolarization prolongation causes lethal torsades de pointes, (TdP). Our primary purpose was to determine whether prolongation of myocardial repolarization as measured by the heart rate‐corrected J‐to‐T peak interval (JTpkc), is associated with repolarization heterogeneity as measured by transmural dispersion, defined as the median duration from the peak to the end of the T wave (TpTe).

Methods

A retrospective cohort study was performed at a single urban tertiary ED from July 2011–September 2012. Inclusion criteria included all consecutive ED patients with ECG based on QTc and QRS intervals. Automated measurements of all intervals were performed. The association of JTpkc with the dependent variable TpTe was assessed after adjustment for QRS and RR interval durations with a multiple linear regression model. A secondary analysis included a similar adjusted assessment of the association of JTpkc with QT dispersion, QTd. Finally, we constructed two multiple regression models to assess the association of clinical causative factors of TdP with TpTe and JTpkc.

Results

Eight hundred seventy‐four cases were included: 186 with QTc <500 ms, 118 with QTc ≥500 and QRS ≥120 ms, and 570 with QTc ≥500 and QRS <120 ms. The coefficient for association of JTpkc with TpTe was ?0.10 (95%CI ?0.15 to ?0.05), and for JTpkc with QTd was 0.03 (95% CI ?0.01 to 0.06). Clinical causative TdP factors were associated more with JTpkc than TpTe.

Conclusion

Repolarization duration as measured by JTpkc is not positively associated with dispersion of repolarization as measured by TpTe or QTd. Dispersion of repolarization may not be a critical mechanistic link between QTc prolongation and TdP.