Distinct spectral dynamics of implanted cardiac defibrillator signals in spontaneous termination of polymorphic ventricular tachycardia and fibrillation in patients with electrical and structural diseases.

AIMS: To determine the spectral dynamics of early spontaneous polymorphic ventricular tachycardia and ventricular fibrillation (PVT/VF) in humans. METHODS AND RESULTS: Fifty-eight self-terminated and 173 shock-terminated episodes of spontaneously initiated PVT/VF recorded by Medtronic implanted cardiac defibrillators (ICDs) in 87 patients with various cardiac pathologies were analyzed by short fast Fourier transform of shifting segments to determine the dynamics of dominant frequency (DF) and regularity index (RI). The progression in the intensity of DF and RI accumulations further quantified the time course of spectral characteristics of the episodes. Episodes of self-terminated PVT/VF lasted 8.6 s [95% confidence interval (CI): 8.1-9.1] and shock-terminated lasted 13.9 s (13.6-14.3) (P < 0.001). Recordings from patients with primarily electrical pathologies displayed higher DF and RI values than those from patients with primarily structural pathologies (P < 0.05) independently of ventricular function or antiarrhythmic drug therapy. Regardless of the underlying pathology, the average DF and RI intensities were lower in self-terminated than shock-terminated episodes [DF: 3.67 (4.04-4.58) vs. 4.32 (3.46-3.93) Hz, P < 0.001; RI: 0.53 (0.48-0.56) vs. 0.63 (0.60-0.65), P < 0.001]. In a multivariate analysis controlled by the type of pathology and clinical variables, regularity remained an independent predictor of self-termination [hazard ratio: 0.954 (0.928-0.980)]. Receiver operating characteristic (ROC) curve analysis of DF and RI intensities demonstrated increased predictability for self-termination in time with 95% CI above the 0.5 cut-off limit at about t = 8.6 s and t = 6.95 s, respectively. CONCLUSION: Consistent with the notion that fast organized sources maintain PVT/VF in humans, reduction of frequency and regularity correlates with early self-termination. Our findings might help generate ICD methods aiming to reduce inappropriate shock deliveries.

Panoramic Endocardial Optical Mapping Demonstrates Serial Rotors Acceleration and Increasing Complexity of Activity During Onset of Cholinergic Atrial Fibrillation.

Background Activation during onset of atrial fibrillation is poorly understood. We aimed at developing a panoramic optical mapping system for the atria and test the hypothesis that sequential rotors underlie acceleration of atrial fibrillation during onset. Methods and Results Five sheep hearts were Langendorff perfused in the presence of 0.25 µmol/L carbachol. Novel optical system recorded activations simultaneously from the entire left and right atrial endocardial surfaces. Twenty sustained (>40 s) atrial fibrillation episodes were induced by a train and premature stimuli protocol. Movies obtained immediately (Initiation stage) and 30 s (Early Stabilization stage) after premature stimulus were analyzed. Serial rotor formation was observed in all sustained inductions and none in nonsustained inductions. In sustained episodes maximal dominant frequency increased from (mean±SD) 11.5±1.74 Hz during Initiation to 14.79±1.30 Hz at Early Stabilization (P<0.0001) and stabilized thereafter. At rotor sites, mean cycle length (CL) during 10 prerotor activations increased every cycle by 0.53% (P=0.0303) during Initiation and 0.34% (P=0.0003) during Early Stabilization. In contrast, CLs at rotor sites showed abrupt decreases after the rotors appearances by a mean of 9.65% (P<0.0001) during both stages. At Initiation, atria-wide accelerations and decelerations during rotors showed a net acceleration result whereby post-rotors atria-wide minimal CL (CLmin) were 95.5±6.8% of the prerotor CLmin (P=0.0042). In contrast, during Early Stabilization, there was no net acceleration in CLmin during accelerating rotors (prerotor=84.9±11.0% versus postrotor=85.8±10.8% of Initiation, P=0.4029). Levels of rotor drift distance and velocity correlated with atria-wide acceleration. Nonrotor phase singularity points did not accelerate atria-wide activation but multiplied during Initiation until Early Stabilization. Increasing number of singularity points, indicating increased complexity, correlated with atria-wide CLmin reduction (P<0.0001). Conclusions Novel panoramic optical mapping of the atria demonstrates shortening CL at rotor sites during cholinergic atrial fibrillation onset. Atrial fibrillation acceleration toward Early Stabilization correlates with the net result of atria-wide accelerations during drifting rotors activity.

NT-proBNP levels in preeclampsia, intrauterine growth restriction as well as in the prediction on an imminent delivery.

OBJECTIVES: Studies of cardiovascular function in pregnancy have shown inconsistent and, in some cases, contradictory results, particularly regarding cardiac output. While some studies report preeclampsia associated with high cardiac output, other studies suggest that preeclampsia should be further subdivided into women with high or low cardiac output. This study was conducted to examine the NT-proBNP levels in preeclampsia, intrauterine growth restriction, and hypertensive pregnancies without preeclampsia. We also examined N-terminal pro-B natriuretic peptide (NT-proBNP) levels three to four months after delivery, in preeclamptic women as well as the prediction of delivery within 10 days. In a reduced number of preeclamptic women and controls we performed echocardiograms to study their diastolic function. METHODS: We investigated the NT-proBNP levels in 213 subjects with preeclampsia only, 73 with intrauterine growth restriction, 44 with preeclampsia and intrauterine growth restriction, 211 who were hypertensive and 662 unaffected pregnancies (controls). We also performed echocardiograms on 36 preeclampsia and 19 controls before delivery and three to five months after delivery. RESULTS: NT-proBNP levels are higher in early onset preeclampsia than in late onset preeclampsia. Intrauterine growth restriction pregnancies showed a NT-proBNP levels similar to hypertensive and unaffected pregnancies. Compared with healthy pregnancies, women with preterm preeclampsia (<37 gestational weeks) had altered left atrial segments. CONCLUSIONS: We observed that NT-proBNP levels are higher in early onset preeclampsia than in late onset. Moreover, diastolic dysfunction is higher in early onset than in late-onset term preeclampsia. An NT-proBNP value >136 pg/mL has a high positive predictive value for an imminent delivery within 10 days.

The clinical impact of untreated slow ventricular tachycardia in patients carrying implantable cardiac defibrillators.

INTRODUCTION: The clinical impact of slow ventricular tachycardia (VT), occurring in patients carrying implantable cardiac defibrillators (ICD), is still under debate. METHODS AND RESULTS: From the UMBRELLA registry (multicenter, observational, and prospective study on patients with ICD), 659 episodes of slow VT were observed in 97 patients. Untreated slow VT (n = 93) had longer duration (23.7 min, CI95%: 10-39), compared with episodes treated effectively by anti-tachycardia pacing (ATP; n = 527; 0.32 min, IC95%: 0.22-0, 48) or shock (n = 39; 1 min, CI95%: 0.8-1.2). Despite of longer duration, the time to the first contact with the medical services was similar to those episodes treated by ATP (50 days [CI95%: 45-55] vs. 41 days [CI95%: 39-44]). However, both were significantly longer than the time observed in episodes treated with shock (10 days, CI95%: 6-15). This tendency was maintained with successive interrogations of the device (2nd and 3rd). There were no significant differences in mortality during follow-up (48 ± 16 months), neither other adverse outcomes, between patients who presented untreated slow TV and those who did not (log-rank p = 0.28). In a Cox regression analysis, the variable "presenting untreated episodes of slow VT" was not able to predict mortality. However, being in sinus rhythm (vs. atrial fibrillation, OR: 0.31, p = 0.009), narrower QRS (OR: 1.036, p = 0.037) and diabetes (OR 4.673, p = 0.049) appropriately predict survival. CONCLUSIONS: Untreated slow VT does not significantly worsen patient prognosis. Our results support the limitation of therapies to ATP only, thus avoiding therapies that have been associated with increased risk of morbidity and mortality.

Congenital long QT syndrome: Should citric fruits be avoided? A case report of a cLQTS type 1 with unusual QTc prolongation with citric juices.

Congenital long QT syndromes (cLQTS) are relatively rare diseases in which QT interval is prolonged due to several mutations on ion channels involved in cardiac cell repolarization. This condition confers higher risk of malignant arrhythmias and sudden cardiac death, and it is widely accepted that substances that prolong QT interval should be avoided by these patients. Most of these substances are antibiotics and non-antibiotics drugs, but almost nothing is known about frequently consumed fruits and juices. We report the case of a patient with a previously asymptomatic cLQTS type 1 (cLQTS1) with unusual QT prolongation of 167 milliseconds (ms) related to the consumption of large amounts of citric juices (oranges and lemons). A literature review was done for better understanding of its influence on QT interval duration and to know the concentration of flavonoids on citric fruits. .

Sodium-Glucose Cotransporter-2 Inhibitors at Discharge from Cardiology Hospitalization Department: Decoding A New Clinical Scenario.

Sodium-glucose cotransporter-2 inhibitors (SGLT-2 inhibitors) are new glucose-lowering drugs (GLDs) with demonstrated cardiovascular benefits in patients with heart disease and type-2 diabetes mellitus (T2DM). However, their safety and efficacy when prescribed at hospital discharge are unexplored. This prospective, observational, longitudinal cohort study included 104 consecutive T2DM patients discharged from the cardiology department between April 2018 and February 2019. Patients were classified based on SGLT-2 inhibitor prescription and adjusted by propensity-score matching. The safety outcomes included discontinuation of GLDs; worsening renal function; and renal, hepatic, or metabolic hospitalization. The efficacy outcomes were death from any cause, cardiovascular death, cardiovascular readmission, and combined clinical outcome (cardiovascular death or readmission). The results showed that, the incidence rates of safety outcomes were similar in the SGLT-2 inhibitor or non-SGLT-2 inhibitor groups. Regarding efficacy, the SGLT-2 inhibitors group resulted in a lower rate of combined clinical outcomes (18% vs. 42%; hazard ratio (HR), 0.35; p = 0.02), any cause death (0% vs. 24%; HR, 0.79; p = 0.001) and cardiovascular death (0% vs. 17%; HR, 0.83; p = 0.005). No significant differences were found in cardiovascular readmissions. SGLT-2 inhibitor prescription at hospital discharge in patients with heart disease and T2DM was safe, well tolerated, and associated with a reduction in all-cause and cardiovascular deaths.

Spectral Analysis of the QT Interval Increases the Prediction Accuracy of Clinical Variables in Brugada Syndrome.

(1) Background: The clinical management of Brugada Syndrome (BrS) remains suboptimal. (2) Objective: To explore the role of standard electrocardiogram (ECG) spectral analysis in diagnosis and risk stratification. (3) Methods: We analyzed 337 patients-43 with a spontaneous type I ECG pattern (Spont-BrS), 112 drug induced (Induct-BrS), and 182 with a negative response to the drug challenge (negative responders (NR)). ECGs were processed using the wavelet transform (high frequency: 85 to 130 Hz). (4) Results: The power of the high-frequency content in the ST segment (Total ST Power; nV²Hz-¹10³) was higher in BrS compared with NR patients (Spont-BrS: 28.126 (7.274-48.978) vs. Induc-BrS: 26.635 (15.846-37.424) vs. NR: 11.13 (8.917-13.343); p = 0.002). No differences were observed between ECG patterns in BrS patients. However, the Total ST Power of the type II or III ECG in NR patients was lower than in the same ECG patterns recorded from BrS patients (BrS: 31.07 (16.856-45.283); vs. NR: 10.8 (7.248-14.352) nV²Hz-¹10³; p = 0.007). The Total ST Power, age, and family history of BrS were independent predictors of positive responses to drug testing. Comparing models with versus those without Total ST Power, the area under the received operator curve (ROC) curve increased (with 0.607 vs. without 0.528, p = 0.001). Only syncope was associated with an increased risk (follow-up 55.8 ± 39.35 months). However, the area under the ROC curve increased significantly when the Total ST Power was included as a covariate (with 0.784 vs. without 0.715, p = 0.04). (5) Conclusions: The analysis of the high-frequency content of ECG signals increases the predictive capability of clinical variables in BrS patients.

The QT Interval Dynamic in a Human Experimental Model of Controlled Heart Rate and QRS Widening.

Background: there is increasing interest for computing corrected QT intervals in patients with prolonged depolarization. We aimed to analyze the effect of prolonged QRS in the QT and in the diagnostic accuracy of frequency-correction. Methods and Results: in 28 patients admitted for self-expanding aortic valve implantation, sequential pacing was performed in the AAI mode in two different phases: before and immediately after the release of the prosthesis. We evaluated the accuracy of the Bazett, Fridericia, Framingham and Hodges formulas with the reference of the QT at 60 bpm (QTc/deviation). The widening of the QRS was the main contributor to the QT prolongation (Pearson 0.79; CI95%: 0.75-0.84). Prolongation in other intervals (ST segment and T-wave) significantly contribute in the higher frequency range (p < 0.05). The Bazett's formula displayed the highest QTc/deviation, while Framingham and Hodges retrieved the lowest QTc/deviation and the best fit (p < 0.001). In addition, the Bazett's formula displayed the highest correlation between variations in the QTc/deviation and the widening of the QRS (Pearson coefficient -0.54; p < 0.001) in comparison with the Fridericia, Framingham and Hodges formulas (-0.51, -0.37 and -0.38 respectively; p < 0.001). There was also a linear effect of the heart rate in the QTc/deviation obtained with the Bazett's formula (p = 0.015), not observed for other formulas. Conclusions: The prolonged depolarization of the ventricles introduces direct and linear prolongation in the QT interval, but also a non-linear distortion in cardiac repolarization that contributes for QT prolongation at the higher frequency range. The Bazett's formula displays significantly higher sensitivity to prolongation of ECG intervals.

Analysis of early failure of Biotronik Linox Smart implantable cardioverter-defibrillator leads: A comparative study of three defibrillator leads.

BACKGROUND AND OBJECTIVES: Early failure of Biotronik Linox and Linox Smart leads (Biotronik, Berlin, Germany) has been reported in numerous recent publications. The aim of this study was to assess the performance of this lead compared with that of two other contemporary leads. METHODS: We conducted an ambispective study of all consecutive first implantations of defibrillator leads carried out in our center: Endotak (model 148, 158, Boston Scientific, Marlborough, MA, USA) (n = 173), Sprint Quattro (model 6644, 6947, Medtronic, Dublin, Ireland) (n = 145), and Linox Smart (Biotronik, model SD 65/16) (n = 120). RESULTS: During a median follow-up of 4.6 ± 2.1 years, failure occurred in nine Linox Smart (7.5%), one Endotak Reliance (0.6%), and no Sprint Quattro leads. The survival probability of the Linox Smart group was significantly lower than that of the Endotak and Sprint Quattro groups measured by the log-rank test (Linox vs Endotak; P < 0.001 and Linox vs Sprint Quattro; P < 0.001). Nonphysiological signals not due to external interference were observed in all Linox Smart leads, with normal parameters and without visible anomalies on chest x-ray. CONCLUSIONS: In this single-center experience, the survival rate of Linox Smart leads was 88% at 5 years of follow-up, which was significantly lower than that of the other leads. Comprehensive vigilance of Linox Smart leads, including home monitoring, may be advisable to facilitate early detection of lead failure and avoid inappropriate shocks.

Analysis of the High-Frequency Content in Human QRS Complexes by the Continuous Wavelet Transform: An Automatized Analysis for the Prediction of Sudden Cardiac Death.

BACKGROUND: Fragmentation and delayed potentials in the QRS signal of patients have been postulated as risk markers for Sudden Cardiac Death (SCD). The analysis of the high-frequency spectral content may be useful for quantification. METHODS: Forty-two consecutive patients with prior history of SCD or malignant arrhythmias (patients) where compared with 120 healthy individuals (controls). The QRS complexes were extracted with a modified Pan-Tompkins algorithm and processed with the Continuous Wavelet Transform to analyze the high-frequency content (85-130 Hz). RESULTS: Overall, the power of the high-frequency content was higher in patients compared with controls (170.9 vs. 47.3 10³nV²Hz-1; p = 0.007), with a prolonged time to reach the maximal power (68.9 vs. 64.8 ms; p = 0.002). An analysis of the signal intensity (instantaneous average of cumulative power), revealed a distinct function between patients and controls. The total intensity was higher in patients compared with controls (137.1 vs. 39 10³nV²Hz-1s-1; p = 0.001) and the time to reach the maximal intensity was also prolonged (88.7 vs. 82.1 ms; p < 0.001). DISCUSSION: The high-frequency content of the QRS complexes was distinct between patients at risk of SCD and healthy controls. The wavelet transform is an efficient tool for spectral analysis of the QRS complexes that may contribute to stratification of risk.

The Prevalence of Patient-Prosthesis Mismatch Can Be Reduced Using the Trifecta Aortic Prosthesis.

BACKGROUND: Some important studies have shown that patient-prosthesis mismatch is a frequent occurrence after surgical aortic valve replacement that impairs survival. The Trifecta valve (St. Jude Medical Inc, St. Paul, MN) has special architecture designed to achieve the best hemodynamic profile. The aim of this study was to determine the prevalence of mismatch when using this prosthesis. METHODS: This study included 1,302 patients at 3 months postoperatively, 339 patients with a Trifecta prosthesis and 963 patients (the control group) with a Mitroflow aortic valve (Sorin Group Inc, Mitroflow Division, Vancouver, Canada). Multinomial multivariate logistic regression was calculated to estimate the association between the Trifecta prosthesis and moderate or severe patient-prosthesis mismatch. RESULTS: Any degree of mismatch was present in 5.9% of the Trifecta group and in 42.4% in the Mitroflow group. Moderate patient-prosthesis mismatch was present in 3.8% of the patients with a Trifecta valve and in 32.6% in the Mitroflow group. Severe mismatch was present in 2.1% of the patients with a Trifecta prosthesis and in 9.8% of the patients with a Mitroflow valve. All differences were statistically significant (p < 0.001). The odds ratio of the Trifecta prosthesis as protector against mismatch was 16.9 (95% confidence interval, 9.5 to 30.4) and 11.9 (95% confidence interval, 5.3 to 26.7) for moderate or severe mismatch, respectively. CONCLUSIONS: The prevalence of patient-prosthesis mismatch using the Trifecta aortic prosthesis is extraordinary low. This finding may have great clinical repercussions in patients undergoing surgical aortic valve replacement.

Anomalous right coronary artery origin with interarterial pathway-importance of morphological origin assessment and the role of percutaneous interventionism.

Anomalies in coronary arteries (CA) are an important issue in cardiology and cardiovascular surgery. Specifically the anomalous origin of the right coronary artery (RCA) is of special importance because it is the most frequent anomaly. Clinical practice guidelines recommend the revascularization treatment in cases of interarterial pathway and documented myocardial ischemia and when hypoplasia, compression or obstruction is evident. We report two different cases of patients with anomalous origin of RCA and associated interarterial pathway. With them we want to highlight the different presentation forms of these patients and the different diagnostic alternatives available in each of the steps. In the patient with anomalous origin of the RCA and associated interarterial pathway, the first step after establishing the diagnosis is to rule out the presence of inducible ischemia. In those patients in whom ischemia induction tests are negative, the second step is to adequately assess the interarterial pathway, in order to rule out obstructions or compressions that also justify revascularization. In those cases in which all the tests are negative, the current evidence does not recommend revascularization, but adequate periodic follow-up is recommended. For this reason, we believe that the stress echocardiogram and exercise perfusion scintigraphy (based on availability and experience in each center) are fundamental because of their high sensitivity and specificity. We would also like to highlight the role that percutaneous interventionism can play in this type of clinical cases. Especially with patients of high surgical risk and in whom the percutaneous approach is feasible.