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.

     

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.

     

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.

     

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.

     

Marked exercise‐induced T‐wave heterogeneity in symptomatic diabetic patients with nonflow‐limiting coronary artery stenosis

Background

T‐wave heterogeneity (TWH) independently predicted cardiovascular mortality in Health Survey 2000 based on 12‐lead ECGs recorded at rest. We investigated whether TWH is elevated during exercise tolerance testing (ETT) in symptomatic diabetic patients with nonflow‐limiting coronary artery stenosis compared to control subjects without diabetes.

Methods

Cases were all patients (n = 20) with analyzable ECG recordings during both rest and ETT who were enrolled in the Effects of Ranolazine on Coronary Flow Reserve (CFR) in Symptomatic Patients with Diabetes and Suspected or Known Coronary Artery Disease (RAND‐CFR) study (NCT01754259); median CFR was 1.44; 80% of cases had CFR <2. Control subjects (n = 9) were nondiabetic patients who had functional flow reserve (FFR) >0.8, a range not associated with inducible ischemia. TWH was analyzed from precordial leads V₄, V₅, and V₆ by second central moment analysis, which assesses the interlead splay of T‐waves about a mean waveform.

Results

During exercise to similar rate‐pressure products (p = .31), RAND‐CFR patients exhibited a 49% increase in TWH during exercise (rest: 49 ± 5 μV; exercise: 73 ± 8 μV, p = .003). By comparison, in control subjects, TWH was not significantly altered (rest: 52 ± 11 μV; ETT: 38 ± 5 μV, p = .19). ETT‐induced ST‐segment depression >1 mm (p = .11) and T_peak‐T_end (p = .18) and QTc intervals (p = .80) failed to differentiate cases from controls.

Conclusions

TWH is capable of detecting latent repolarization abnormalities, which are present during ETT in diabetic patients with nonflow‐limiting stenosis but not in control subjects. The technique developed in this study permits TWH analysis from archived ECGs and thereby enables mining of extensive databases for retrospective studies and hypothesis testing.

     

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.

     

Propensity score matching analysis of the impact of Syntax score and Syntax score II on new onset atrial fibrillation development in patients with ST segment elevation myocardial infarction

Background

New‐onset atrial fibrillation (NOAF) is a common complication in the setting of ST segment elevation myocardial infarction (STEMI), and worsened short/long‐term prognosis. Several clinical parameters have already been associated with NOAF development. However, relationship between NOAF and coronary artery disease (CAD) severity in STEMI patients is unclear. This study evaluates the relationship between NOAF and CAD severity using Syntax score (SS) and Syntax score II (SSII) in STEMI patients who were treated with primary percutaneous coronary intervention (pPCI).

Method

We enrolled 1,565 consecutive STEMI patients who were treated with pPCI. Patients with NOAF were compared to patients without NOAF in the entire study population and in a matched population defined by propensity score matching.

Results

Patients with NOAF had significantly higher SS and SSII than those without, both in the matched population (18.6 ± 4 vs 16.75 ± 3.6; p < .001 and 42 ± 13.4 vs 35.1 ± 13.1; p < .001, respectively), and in all study population (18.6 ± 4 vs 16.5 ± 4.6; p < .001 and 42 ± 13.3 vs 31.5 ± 11.9; p < .001 respectively). SSII, compared to its components, was the only independent predictor of NOAF (OR: 1,041 95% CI: 1.015–1.068; p = .002). In the long‐term follow‐up, all‐cause long‐term mortality was significantly higher in patients with NOAF than those without NOAF (23.3% vs. 11%; p = .032).

Conclusion

This is the first study to comprehensively examine the relationship between NOAF development and CAD severity using SS and SSII. We demonstrated that, in STEMI patients, high SSII was significantly related to NOAF and was an independent predictor of NOAF. Furthermore, patients with NOAF were associated with poor prognosis.

     

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.

     

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.

     

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.

     

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.

     

Fine versus coarse atrial fibrillation in rheumatic mitral stenosis: The impact of aging and the clinical significance

Background

Atrial fibrillation (AF) as the most rhythm disturbance in patients with rheumatic mitral stenosis (MS), is classified in to coarse and fine subtypes according to the height of fibrillatory wave amplitude. The aim of this study is to identify the factors associated with the presence of fine versus coarse morphology in patients with rheumatic MS.

Methods

In this cross‐sectional study, patients with confirmed diagnosis of severe rheumatic MS admitted between March 2013 and March 2017 were screened. Patients were categorized to sinus rhythm (SR) and AF rhythm (coarse and fine subtypes) groups according to the admission electrocardiogram. The association between various clinical and echocardiographic factors and the development of fine versus coarse AF were examined.

Results

Among 754 patients with the diagnosis of rheumatic MS, 288 (198 female) were found to have AF (38%). Among them 206 (71.5%), and 82 (28.5%) patients had fine and coarse morphology respectively. Patient in these two groups were quite similar in terms of echocardiographic parameters and comorbidities. However, patients with fine morphology AF were significantly older. (p‐Value=.007).

Conclusion

Coarse morphology of AF is common in patients with rheumatic MS. While echocardiographic or most clinical parameters do not seem to associate with the occurrence of coarse or fine morphology, age seems to be the only independent factor correlated with the presence of fine subtype of AF in this population.

     

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.

     

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.

     

The impact of successful revascularization of coronary chronic total occlusions on long‐term clinical outcomes in patients with non‐ST‐segment elevation myocardial infarction

Objectives

The purpose of this study was to assess the long‐term clinical impact of revascularization of coronary concomitant coronary chronic total occlusion (CTO) in patients with Non‐ST‐segment elevation myocardial infarction (NSTEMI).

Background

CTO is associated with poorer prognosis in patients with NSTEMI. The evidence of revascularization of CTO in patients with NSTEMI is still conflicting.

Methods

Consecutive patients with NSTEMI and CTO who underwent percutaneous coronary intervention (PCI) within 72 h of admission from 2006 to 2015 were retrospectively recruited and analyzed. A total of 967 patients underwent PCI for NSTEMI. Among them, 106 (11%) patients had concomitant CTO and were recruited for analysis. CTO lesions were revascularized successfully in 67 (63.2%) patients (successful CTO PCI group), while the CTO in the remaining 39 patients were either not attempted or failed (No/failed CTO PCI group).

Results

The 30‐day cardiac death and major adverse cardiac events (MACE) were significantly lower in the successful CTO PCI group (both cardiac death and MACE were 3% vs 30%, P < 0.001, respectively). A landmark analysis set at 30th day for 30‐day survivals was performed. After a mean of 2.5‐year follow‐up, the long‐term cardiac death was still significantly lower (16.9% vs 42.3%, P < 0.001), whereas the MACE showed a trend toward lower incidence (26.2% vs 40.7%, P = 0.051) in the successful CTO PCI group. In multivariate Cox regression analysis, successful revascularization of CTO is an independent protective predictor for long‐term cardiac death (HR 0.310, 95% CI, 0.109‐0.881, P = 0.028) in all population and in propensity‐score matched cohort (P = 0.007).

Conclusions

Successful revascularization of CTO was associated with reduced risk of long‐term cardiac death in patients with NSTEMI and concomitant CTO.

     

Heart rate recovery fast‐to‐slow phase transition: Influence of physical fitness and exercise intensity

Background

Postexercise heart rate (HR) recovery presents an exponential decay, with two distinct phases: a fast phase, characterized by abrupt decay of HR, and determined by parasympathetic reactivation; and a slow phase, characterized by gradual decay of HR, and predominantly determined by sympathetic withdrawal. Although several methods have been proposed to assess postexercise HR recovery, none of those methods selectively assesses the time of transition from the fast to the slow phase of the HR recovery curve (HRR_PT), and the magnitude of decay prior to (HRR_FP) and after this point (HRR_SP). Therefore, the aim of the present study was to propose a method to identify HRR_PT, HRR_FP, and HRR_SP and to verify the effects of exercise intensity and physical fitness on such parameters.

Methods

Ten healthy young participants (24 ± 3 years; 23.6 ± 1.7 kg/m²) randomly underwent two exercise sessions (30 min of cycling), at moderate (MI) and high intensity (HI); followed by 5 min of inactive recovery. HR was continuously recorded during the sessions. The algorithm for HRR_PT analysis was written in Python and is freely available online.

Results

HRR_PT and HRR_SP were increased in HI session compared with MI (81 ± 24 vs. 60 ± 20 s; 8 ± 10 vs. 1 ± 5 bpm; p = .04), and there was no difference in HRR_FP between sessions (49 ± 15 vs. 46 ± 10 bpm; p = .17). In addition, HRR_PT for MI exercise session was significantly and negatively associated with VO_2max (r = ‐0.85, p < .05).

Conclusion

The method herein presented was sensitive to exercise intensity, and partially responsive to aerobic fitness. Next studies should perform the pharmacological and clinical validations of the method.

     

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.

     

Coronary sinus lead delay index for optimization of coronary sinus lead placement

Aim

Optimization of coronary sinus (CS) lead position to the latest activated left ventricular (LV) area is important to increase cardiac resynchronization therapy (CRT) response. We aimed to detect the relationship between coronary sinus lead delay index (CSDI) and echocardiographic, electrocardiographic response to CRT treatment.

Methods

We prospectively included 137 consecutive patients with heart failure (HF) diagnosis, QRS ≥ 120 ms, left bundle branch block (LBBB), New York Heart Association score (NYHA) II–IV, LV ejection fraction (LVEF) <35% and scheduled for CRT (84 male, 53 female; mean age 65.1 ± 10.1 years). Echocardiographic CRT response was defined as ≥15% reduction in LV end‐systolic volume (LVESV). CS lead sensing delay was calculated as the time interval from the onset of surface QRS wave to the onset of depolarization wave recorded from the CS lead by using the CS pacing lead as a bipolar electrode. CSDI was calculated by dividing the CS lead sensing delay by the QRS duration.

Results

LVESV reduction was associated with baseline QRS width (r = .257, p = .002), QRS narrowing (r = .396, p < .001), CSDI (r = .357, p < .001), and NT‐proBNP (r = ?0.213, p = .022) in bivariate analysis. In logistic regression analysis, CSDI was found to be only independent parameter for predicting significant LVESV reduction (Beta = 0.318, p < .001). CSDI was also found to be significantly associated with LVEF increase (r = .244, p = .004) and QRS narrowing (r = .178, p = .046).

Conclusion

CSDI may be used as a marker to predict the favorable response to CRT. It may be useful to integrate CSDI to CRT implantation procedure in order to minimize nonresponders.

     

A new modality for the estimation of corrected flow time via electrocardiography as an alternative to Doppler ultrasonography

Background

Evaluation of corrected flow time (FTc) via ultrasonography is one of the suggested modalities for the assessment of intravascular volume status. This study aimed to compare the results of FTc of carotid artery measured via ultrasonography, as a measure of mechanical outcome of the cardiac cycle, with the results of FTc estimation from a new modified formula via electrocardiography (ECG), as a measure of electrical function of the cardiac cycle.

Methods

Healthy volunteers were evaluated before and after a passive leg raising (PLR) maneuver. FTc was measured concurrently before and after PLR via a modified method from ECG and via ultrasonography of the carotid artery.

Results

A total number of 98 healthy volunteers (51 women and 47 men) with a mean age of 30.69 ± 6.28 years were included. There was a significant correlation between FTc measured by ultrasonography and estimated by ECG both before PLR and after PLR (r = .878, p < .0001 and r = .797, p < .0001, respectively). Changes in FTc were slightly higher in measurements by ultrasonography compared to estimations by ECG (22.33 ± 17.15 ms^0.5 vs. 15.86 ± 14.25 ms^0.5, p = .001).

Conclusion

Estimation of FTc via ECG is potentially an effective and feasible method for the assessment of volume status at the clinical settings. Further investigations should determine the significance of differences that may be observed between ultrasonography and ECG in patients with either dehydration or volume overload and in the need of real‐time volume status assessment.

     

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.