Stochastic spontaneous calcium release events and sodium channelopathies promote ventricular arrhythmias

Premature ventricular complexes (PVCs), the first initiating beats of a variety of cardiac arrhythmias, have been associated with spontaneous calcium release (SCR) events at the cell level. However, the mechanisms underlying the degeneration of such PVCs into arrhythmias are not fully understood. The objective of this study was to investigate the conditions under which SCR-mediated PVCs can lead to ventricular arrhythmias. In particular, we sought to determine whether sodium (Na⁺) current loss-of-function in the structurally normal ventricles provides a substrate for unidirectional conduction block and reentry initiated by SCR-mediated PVCs. To achieve this goal, a stochastic model of SCR was incorporated into an anatomically accurate compute model of the rabbit ventricles with the His-Purkinje system (HPS). Simulations with reduced Na⁺ current due to a negative-shift in the steady-state channel inactivation showed that SCR-mediated delayed afterdepolarizations led to PVC formation in the HPS, where the electrotonic load was lower, conduction block, and reentry in the 3D myocardium. Moreover, arrhythmia initiation was only possible when intrinsic electrophysiological heterogeneity in action potential within the ventricles was present. In conclusion, while benign in healthy individuals SCR-mediated PVCs can lead to life-threatening ventricular arrhythmias when combined with Na⁺ channelopathies.

Premature Ventricular Contractions Producing Brockenbrough-Braunwald Sign in Obstructive Cardiomyopathy

Increased dynamic flow in hypertrophic obstructive cardiomyopathy depicts a classic sign on invasive pressure tracings of the aorta and left ventricle, simultaneously known as the Brockenbrough-Braunwald sign, which is demonstrated in the presented case.

[Malignant bileaflet mitral valve prolapse syndrome in otherwise idiopathic ventricular fibrillation]

A 32-year-old, otherwise healthy woman was admitted after successful out-of-hospital resuscitation due to ventricular fibrillation. Established cardiac, pulmonary, metabolic, and toxicological causes were excluded. However, persisting (biphasic) negative T waves in the inferior ECG leads and premature ventricular contractions (PVC) were noted. PVC morphology indicated a focus alternating between the posterior papillary muscle/the left posterior fascicle and the left ventricular outflow tract region/anterior papillary muscle. Echocardiography revealed a bileaflet mitral prolapse with mild mitral valve regurgitation. This case is a typical presentation of the recently described malignant bileaflet mitral valve prolapse syndrome. The patient was discharged without overt neurological deficit after implantation of a cardioverter-defibrillator.

PVCs, PVC-Induced Cardiomyopathy, and the Role of Catheter Ablation

Premature ventricular contractions (PVCs) are common arrhythmias noticed in the clinical setting because of premature depolarization of the ventricular myocytes. Although often thought to be reflective of underlying disease rather than intrinsically harmful, PVCs have recently been linked with worse outcomes in patients without significant cardiac disease. Long-term exposure to a high PVC burden can lead to the development of PVC-induced cardiomyopathy. The pathogenesis of this condition is poorly understood at the current time. Many studies have suggested that catheter ablation of these PVCs may result in reversal of the PVC-induced cardiomyopathy. This article will go over the natural history of PVCs and PVC-induced cardiomyopathy, as well as review the current literature on the role of catheter ablation in treating PVC-induced cardiomyopathy.

[Ventricular arrhythmias in ion channel diseases]

In patients with ion channel disease the predominant arrhythmias are polymorphic ventricular tachycardias (VT), torsade de pointes tachycardia and ventricular fibrillation (VF). In only extremely rare cases is very rapid monomorphic ventricular tachycardia observed. This is why implantable cardioverter-defibrillators (ICDs) should always be programmed for treatment of VF only with high detection rates to avoid inappropriate discharges. In idiopathic VF and catecholaminergic polymorphic ventricular tachycardia (CPVT), no baseline electrocardiographic abnormalities can be detected, whereas in Brugada syndrome, long QT syndrome, early repolarisation syndrome and Anderson-Tawil syndrome alterations of the baseline ECG are very important to identify patients at risk.

Clinical and electrocardiographic characteristics of infarctional ventricular ectopic beats: An observational study

The purpose of this study was to explore the clinical and electrocardiographic characteristics of infarctional ventricular ectopic beats (IVEBs).Thirty-eight acute myocardial infarction (AMI) patients with IVEB and 109 AMI patients without IVEB were analyzed. The morphological changes of QRS complex, ST segment, and T wave were compared to IVEB with sinus rhythm from the same period and fully evolved phase.An IVEB QRS complex often revealed the right bundle branch block morphology, in addition to Q wave AMI; no-Q wave AMI also had IVEB. Single-factor analysis found that IVEB often appeared in early AMI (<6 hours), and they were more frequent in inferoposterior with/without right ventricular involvement, large area AMI and thrombolytic reperfusion than in anterior or anteroseptal myocardial infarction, small area AMI, and unthrombolytic nonreperfusion. Multifactors no conditional logistic regression analysis revealed a positive correlation between IVEB and early AMI, AMI size, Killip heart function degree, inferoposterior with/without right ventricular involvement, and thrombolytic reperfusion. The Q wave of IVEB was wider, and the ST segment elevation was higher than those of the same period in sinus rhythms. The infarctional morphological changes of IVEB could be found before the same period in sinus rhythm and elevated myocardial enzymes.IVEBs were not rare. They were useful for early diagnosis and location of AMI.

Characteristics of diurnal ventricular premature complex variation in right ventricular outflow tract arrhythmias after catheter ablation

Diurnal variations in ventricular tachyarrhythmias (VAs) have been demonstrated in idiopathic arrhythmogenic heart disease. The electrophysiological characteristics of diurnal variations in idiopathic right ventricular outflow tract (RVOT) VA have not previously been elucidated. Sixty-two consecutive patients undergoing catheter ablation for idiopathic RVOT VA (mean age: 42.8 ± 12.3 years, 35 females) were enrolled. The diurnal variation type (group 1, n = 36) was defined as those patients who had most ventricular premature contractions (VPCs) during the night hours by preprocedure Holter recordings. Group 2 (n = 26) was defined as those patients who did not have significant VPC variations. The baseline characteristics and electrophysiological properties were collected and analyzed, and the rates of recurrence after catheter ablation were compared between the 2 groups. In this study, heart rate variability analysis demonstrated lower low frequency/high frequency ratios in group 1 than in group 2 (3.95 ± 3.08 vs 6.26 ± 5.33; P = 0.042). There were no significant differences in baseline characteristics, echocardiography and electrophysiological characteristics between the 2 groups. During a mean follow-up period of 13.5 ± 11.0 months, a total of 16 patients had VA recurrences, including 13 patients from group 1 and 3 patients from group 2 (36.1% vs 12.5%, P = 0.039). This study demonstrated the effect of the autonomic nervous system in idiopathic RVOT VAs and that the diurnal variation type leads to a higher recurrence rate after catheter ablation.

Premature Ventricular Complex Ablation in Structural Heart Disease

Frequent premature ventricular complexes (PVCs) in patients with underlying structural heart disease, particular after myocardial infarction, can predict increased mortality. Use of antiarrhythmic medications to suppress PVCs in this setting can result in a further increase in mortality. High PVC burdens in patients with structural heart disease can cause or worsen cardiomyopathy and successful elimination of PVCs with catheter ablation can improve or, in some cases normalize, cardiac function. PVCs may also trigger more malignant ventricular arrhythmias, particularly in patients with previous myocardial infarction, and when identified can be mapped and ablated.

Use of self-gated radial cardiovascular magnetic resonance to detect and classify arrhythmias (atrial fibrillation and premature ventricular contraction)

BACKGROUND

Arrhythmia can significantly alter the image quality of cardiovascular magnetic resonance (CMR); automatic detection and sorting of the most frequent types of arrhythmias during the CMR acquisition could potentially improve image quality. New CMR techniques, such as non-Cartesian CMR, can allow self-gating: from cardiac motion-related signal changes, we can detect cardiac cycles without an electrocardiogram. We can further use this data to obtain a surrogate for RR intervals (valley intervals: VV). Our purpose was to evaluate the feasibility of an automated method for classification of non-arrhythmic (NA) (regular cycles) and arrhythmic patients (A) (irregular cycles), and for sorting of common arrhythmia patterns between atrial fibrillation (AF) and premature ventricular contraction (PVC), using the cardiac motion-related signal obtained during self-gated free-breathing radial cardiac cine CMR with compressed sensing reconstruction (XD-GRASP).

METHODS

One hundred eleven patients underwent cardiac XD-GRASP CMR between October 2015 and February 2016; 33 were included for retrospective analysis with the proposed method (6 AF, 8 PVC, 19 NA; by recent ECG). We analyzed the VV, using pooled statistics (histograms) and sequential analysis (Poincaré plots), including the median (medVV), the weighted mean (meanVV), the total number of VV values (VVval), and the total range (VVTR) and half range (VVHR) of the cumulative frequency distribution of VV, including the median to half range (medVV/VVHR) and the half range to total range (VVHR/VVTR) ratios. We designed a simple algorithm for using the VV results to differentiate A from NA, and AF from PVC.

RESULTS

Between NA and A, meanVV, VVval, VVTR, VVHR, medVV/VVHR and VVHR/VVTR ratios were significantly different (p values = 0.00014, 0.0027, 0.000028, 5×10-9, 0.002, respectively). Between AF and PVC, meanVV, VVval and medVV/VVHR ratio were significantly different (p values = 0.018, 0.007, 0.044, respectively). Using our algorithm, sensitivity, specificity, and accuracy were 93 %, 95 % and 94 % to discriminate between NA and A, and 83 %, 71 %, and 77 % to discriminate between AF and PVC, respectively; areas under the ROC curve were 0.93 and 0.89.

CONCLUSIONS

Our study shows we can reliably detect arrhythmias and differentiate AF from PVC, using self-gated cardiac cine XD-GRASP CMR.

Percutaneous Pulmonary Valve Implantation Alters Electrophysiologic Substrate

BACKGROUND

Percutaneous pulmonary valve implantation (PPVI) is first-line therapy for some congenital heart disease patients with right ventricular outflow tract dysfunction. The hemodynamics improvements after PPVI are well documented, but little is known about its effects on the electrophysiologic substrate. The objective of this study is to assess the short- and medium-term electrophysiologic substrate changes and elucidate postprocedure arrhythmias.

METHODS AND RESULTS

A retrospective chart review of patients undergoing PPVI from May 2010 to April 2015 was performed. A total of 106 patients underwent PPVI; most commonly these patients had tetralogy of Fallot (n=59, 55%) and pulmonary insufficiency (n=60, 57%). The median follow-up time was 28 months (7-63 months). Pre-PPVI, 25 patients (24%) had documented arrhythmias: nonsustained ventricular tachycardia (NSVT) (n=9, 8%), frequent premature ventricular contractions (PVCs) (n=6, 6%), and atrial fibrillation/flutter (AF/AFL) (n=10, 9%). Post-PPVI, arrhythmias resolved in 4 patients who had NSVT (44%) and 5 patients who had PVCs (83%). New arrhythmias were seen in 16 patients (15%): 7 NSVT, 8 PVCs, and 1 AF/AFL. There was resolution at medium-term follow-up in 6 (86%) patients with new-onset NSVT and 7 (88%) patients with new-onset PVCs. There was no difference in QRS duration pre-PPVI, post-PPVI, and at medium-term follow-up (P=0.6). The median corrected QT lengthened immediately post-PPVI but shortened significantly at midterm follow-up (P<0.01).

CONCLUSIONS

PPVI reduced the prevalence of NSVT. The majority of postimplant arrhythmias resolve by 6 months of follow-up.

Premature Ventricular Complexes in Apparently Normal Hearts

Premature ventricular complexes (PVCs) are consistently associated with worse prognosis and higher morbidity and mortality. This article reviews PVCs and their presentation in patients with an apparently normal heart. Patients with PVCs may be completely asymptomatic, whereas others may note severely disabling symptoms. Cardiomyopathy may occur with frequent PVCs. Diagnostic work-up is directed at obtaining 12-lead ECG to characterize QRS morphology, Holter monitor to assess frequency, and echo and advanced imaging to assess for early cardiomyopathy and exclude structural heart disease. Options for management include watchful waiting, medical therapy, or catheter ablation. Malignant variants of PVCs may induce ventricular fibrillation even in a normal heart.

Convolutional Neural Networks for patient-specific ECG classification

We propose a fast and accurate patient-specific electrocardiogram (ECG) classification and monitoring system using an adaptive implementation of 1D Convolutional Neural Networks (CNNs) that can fuse feature extraction and classification into a unified learner. In this way, a dedicated CNN will be trained for each patient by using relatively small common and patient-specific training data and thus it can also be used to classify long ECG records such as Holter registers in a fast and accurate manner. Alternatively, such a solution can conveniently be used for real-time ECG monitoring and early alert system on a light-weight wearable device. The experimental results demonstrate that the proposed system achieves a superior classification performance for the detection of ventricular ectopic beats (VEB) and supraventricular ectopic beats (SVEB).

Prognostic Role of Ventricular Ectopic Beats in Systemic Sclerosis: A Prospective Cohort Study Shows ECG Indexes Predicting the Worse Outcome

Background

Arrhythmias are frequent in Systemic Sclerosis (SSc) and portend a bad prognosis, accounting alone for 6% of total deaths. Many of these patients die suddenly, thus prevention and intensified risk-stratification represent unmet medical needs. The major goal of this study was the definition of ECG indexes of poor prognosis.

Methods

We performed a prospective cohort study to define the role of 24h-ECG-Holter as an additional risk-stratification technique in the identification of SSc-patients at high risk of life-threatening arrhythmias and sudden cardiac death (SCD). One-hundred SSc-patients with symptoms and/or signs suggestive of cardiac involvement underwent 24h-ECG-Holter. The primary end-point was a composite of SCD or need for implantable cardioverter defibrillator (ICD).

Results

Fifty-six patients (56%) had 24h-ECG-Holter abnormalities and 24(24%) presented frequent ventricular ectopic beats (VEBs). The number of VEBs correlated with high-sensitive cardiac troponin T (hs-cTnT) levels and inversely correlated with left-ventricular ejection fraction (LV-EF) on echocardiography. During a mean follow-up of 23.1±16.0 months, 5 patients died suddenly and two required ICD-implantation. The 7 patients who met the composite end-point had a higher number of VEBs, higher levels of hs-cTnT and NT-proBNP and lower LV-EF (p = 0.001 for all correlations). All these 7 patients had frequent VEBs, while LV-EF was not reduced in all and its range was wide. At ROC curve, VEBs>1190/24h showed 100% of sensitivity and 83% of specificity to predict the primary end-point (AUROC = 0.92,p<0.0001). Patients with VEBS>1190/24h had lower LV-EF and higher hs-cTnT levels and, at multivariate analysis, the presence of increased hs-cTnT and of right bundle branch block on ECG emerged as independent predictors of VEBs>1190/24h. None of demographic or disease-related characteristics emerged as predictors of poor outcome.

Conclusions

VEBS>1190/24h identify patients at high risk of life-threatening arrhythmic complications. Thus, 24h-ECG-Holter should be considered a useful additional risk-stratification test to select SSc-patients at high-risk of SCD, in whom an ICD-implantation could represent a potential life-saving intervention.

On the Influence of Heart Rate and Coupling Interval Prematurity on Heart Rate Turbulence

OBJECTIVE

Heart rate turbulence (HRT) has been successfully explored for cardiac risk stratification. While HRT is known to be influenced by the heart rate (HR) and the coupling interval (CI), nonconcordant results have been reported on how the CI influences HRT. The purpose of this study is to investigate HRT changes in terms of CI and HR by means of an especially designed protocol.

METHODS

A dataset was acquired from 11 patients with structurally normal hearts for which CI was altered by different pacing trains and HR by isoproterenol during electrophysiological study (EPS). The protocol was designed so that, first, the effect of HR changes on HRT and, second, the combined effect of HR and CI could be explored. As a complement to the EPS dataset, a database of 24-h Holters from 61 acute myocardial infarction (AMI) patients was studied for the purpose of assessing risk. Data analysis was performed by using different nonlinear ridge regression models, and the relevance of model variables was assessed using resampling methods. The EPS subjects, with and without isoproterenol, were analyzed separately.

RESULTS

The proposed nonlinear regression models were found to account for the influence of HR and CI on HRT, both in patients undergoing EPS without isoproterenol and in low-risk AMI patients, whereas this influence was absent in high-risk AMI patients. Moreover, model coefficients related to CI were not statistically significant, p > 0.05, on EPS subjects with isoproterenol.

CONCLUSION

The observed relationship between CI and HRT, being in agreement with the baroreflex hypothesis, was statistically significant ( ), when decoupling the effect of HR and normalizing the CI by the HR.

SIGNIFICANCE

The results of this study can help to provide new risk indicators that take into account physiological influence on HRT, as well as to model how this influence changes in different cardiac conditions.

Quantification of Left Ventricular Function With Premature Ventricular Complexes Reveals Variable Hemodynamics

BACKGROUND

Premature ventricular complexes (PVCs) are prevalent in the general population and are sometimes associated with reduced ventricular function. Current echocardiographic and cardiovascular magnetic resonance imaging techniques do not adequately address the effect of PVCs on left ventricular function.

METHODS AND RESULTS

Fifteen subjects with a history of frequent PVCs undergoing cardiovascular magnetic resonance imaging had real-time slice volume quantification performed using a 2-dimensional (2D) real-time cardiovascular magnetic resonance imaging technique. Synchronization of 2D real-time imaging with patient ECG allowed for different beats to be categorized by the loading beat RR duration and beat RR duration. For each beat type, global volumes were quantified via summation over all slices covering the entire ventricle. Different patterns of ectopy, including isolated PVCs, bigeminy, trigeminy, and interpolated PVCs, were observed. Global functional measurement of the different beat types based on timing demonstrated differences in preload, stroke volume, and ejection fraction. An average of hemodynamic function was quantified for each subject depending on the frequency of each observed beat type.

CONCLUSIONS

Application of real-time cardiovascular magnetic resonance imaging in patients with PVCs revealed differential contribution of PVCs to hemodynamics.

Use of an Implantable Loop Recorder in a Chimpanzee (Pan troglodytes) to Monitor Cardiac Arrhythmias and Assess the Effects of Acupuncture and Laser Therapy

Cardiovascular disease is a leading cause of death in captive chimpanzees and is often associated with myocardial fibrosis, which increases the risk of cardiac arrhythmias. In this case report, we present a 36-y-old male chimpanzee (Pan troglodytes) diagnosed with frequent ventricular premature complexes (VPC). We placed a subcutaneous implantable loop recorder for continual ECG monitoring to assess his arrhythmias without the confounding effects of anesthetics. During his initial treatment with the antiarrhythmia medication amiodarone, he developed thrombocytopenia, and the drug was discontinued. After reviewing other potential therapies for the treatment of cardiac arrhythmias, we elected to try acupuncture and laser therapy in view of the positive results and the lack of adverse side effects reported in humans. We used 2 well-known cardiac acupuncture sites on the wrist, PC6 (pericardium 6) and HT7 (heart 7), and evaluated the results of the therapy by using the ECG recordings from the implantable loop recorder. Although periodic increases in the animal's excitement level introduced confounding variables that caused some variation in the data, acupuncture and laser therapy appeared to decrease the mean number of VPC/min in this chimpanzee.

XD-GRASP: Golden-angle radial MRI with reconstruction of extra motion-state dimensions using compressed sensing

PURPOSE

To develop a novel framework for free-breathing MRI called XD-GRASP, which sorts dynamic data into extra motion-state dimensions using the self-navigation properties of radial imaging and reconstructs the multidimensional dataset using compressed sensing.

METHODS

Radial k-space data are continuously acquired using the golden-angle sampling scheme and sorted into multiple motion-states based on respiratory and/or cardiac motion signals derived directly from the data. The resulting undersampled multidimensional dataset is reconstructed using a compressed sensing approach that exploits sparsity along the new dynamic dimensions. The performance of XD-GRASP is demonstrated for free-breathing three-dimensional (3D) abdominal imaging, two-dimensional (2D) cardiac cine imaging and 3D dynamic contrast-enhanced (DCE) MRI of the liver, comparing against reconstructions without motion sorting in both healthy volunteers and patients.

RESULTS

XD-GRASP separates respiratory motion from cardiac motion in cardiac imaging, and respiratory motion from contrast enhancement in liver DCE-MRI, which improves image quality and reduces motion-blurring artifacts.

CONCLUSION

XD-GRASP represents a new use of sparsity for motion compensation and a novel way to handle motions in the context of a continuous acquisition paradigm. Instead of removing or correcting motion, extra motion-state dimensions are reconstructed, which improves image quality and also offers new physiological information of potential clinical value.

Consumption of Caffeinated Products and Cardiac Ectopy

BACKGROUND

Premature cardiac contractions are associated with increased morbidity and mortality. Though experts associate premature atrial contractions (PACs) and premature ventricular contractions (PVCs) with caffeine, there are no data to support this relationship in the general population. As certain caffeinated products may have cardiovascular benefits, recommendations against them may be detrimental.

METHODS AND RESULTS

We studied Cardiovascular Health Study participants with a baseline food frequency assessment, 24-hour ambulatory electrocardiography (Holter) monitoring, and without persistent atrial fibrillation. Frequencies of habitual coffee, tea, and chocolate consumption were assessed using a picture-sort food frequency survey. The main outcomes were PACs/h and PVCs/hour. Among 1388 participants (46% male, mean age 72 years), 840 (61%) consumed ≥1 caffeinated product per day. The median numbers of PACs and PVCs/h and interquartile ranges were 3 (1-12) and 1 (0-7), respectively. There were no differences in the number of PACs or PVCs/h across levels of coffee, tea, and chocolate consumption. After adjustment for potential confounders, more frequent consumption of these products was not associated with ectopy. In examining combined dietary intake of coffee, tea, and chocolate as a continuous measure, no relationships were observed after multivariable adjustment: 0.48% fewer PACs/h (95% CI -4.60 to 3.64) and 2.87% fewer PVCs/h (95% CI -8.18 to 2.43) per 1-serving/week increase in consumption.

CONCLUSIONS

In the largest study to evaluate dietary patterns and quantify cardiac ectopy using 24-hour Holter monitoring, we found no relationship between chronic consumption of caffeinated products and ectopy.

Image features of spectral correlation function for arrhythmia classification

Recently, computerized arrhythmia classification tools have been intensively used to aid physicians to recognize different irregular heartbeats. In this paper, we introduce arrhythmia CAD system exploiting cyclostationary signal analysis through estimation of the spectral correlation function for 5 different beat types. Two experiments were performed. Raw spectral correlation data were used as features in the first experiment while the other experiment which dealt with the spectral correlation coefficients as image included extraction of wavelet and shape features followed by fisher score for dimensionality reduction. As for the classification task, Support Vector Machine (SVM) with linear kernel was used for both experiments. The experimental results showed that both proposed approaches are superior compared to several state of the art methods. This approach achieved sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of 99.20%, 99.70%, 98.60%, 99.90% and 97.60% respectively.

Frequent Premature Ventricular Complexes Originating from the Left Ventricular Summit Successfully Ablated from the Proximal Great Cardiac Vein Using an Impedance-based Electroanatomical Mapping System

We herein report a 58-year-old woman with frequent premature ventricular complexes (PVCs) originating from the left ventricular summit. The earliest ventricular activation of spontaneous PVCs was recorded in the proximal site of the great cardiac vein, which was simultaneously mapped and conducted using an impedance-based electroanatomical mapping system. Irrigated radiofrequency with a starting power output of 20 W and maximal temperature set at 40°C was applied with 10 Ω impedance fall, resulting in total disappearance of the frequent PVCs. The patient has remained free from PVCs for 18 months without requiring antiarrhythmic drug therapy.

Ambulatory Monitoring and Arrhythmic Outcomes in Pediatric and Adolescent Patients With Duchenne Muscular Dystrophy

BACKGROUND

Patients with Duchenne Muscular Dystrophy (DMD) develop cardiac fibrosis and dilated cardiomyopathy. We described the frequency of significant Holter findings in DMD, the relationship between cardiac function and arrhythmia burden, and the impact of these findings on clinical management.

METHODS AND RESULTS

A retrospective review was done of patients with DMD who received a Holter from 2010 to 2014. Clinical and arrhythmic outcomes were analyzed. Patients were classified based on left ventricular ejection fraction (LVEF): ≥55%, 35% to 54% and <35%. Significant Holter findings included atrial tachycardia, ventricular tachycardia and atrial fibrillation/flutter. Logistic regression was used to assess predictors of significant Holter findings and change in care. The study included 442 Holters in 235 patients. Mean age was 14±4 years. Patients with cardiac dysfunction were older, and had increased late gadolinium enhancement and left ventricular dilation (P<0.01). There were 3 deaths (1%), all with normal function and none cardiac. Patients with LVEF <35% had more arrhythmias including nonsustained atrial tachycardia (P=0.01), frequent premature ventricular contractions, ventricular couplets/triplets, and nonsustained ventricular tachycardia (P<0.001) compared to the other groups. LVEF <35% (P<0.001) was the only predictor of clinically significant Holter finding. Four patients (40%) had change in medication in the LVEF <35% group compared to 9 (3%) in the ≥55% and 4 (4%) in the 35% to 54% groups (P<0.001).

CONCLUSIONS

Sudden cardiac events are rare in DMD patients with an LVEF >35%. Significant Holter findings are rare in patients with DMD who have an LVEF >35%, and cardiac dysfunction appears to predict significant Holter findings. Holter monitoring is highest yield among DMD patients with cardiac dysfunction.

Patients with exercise-associated ventricular ectopy present evidence of myocarditis

BACKGROUND

The origin and clinical relevance of exercise-induced premature ventricular beats (PVBs) in patients without coronary heart disease or cardiomyopathies is unknown. Cardiovascular magnetic resonance enables us to non-invasively assess myocardial scarring and oedema. The purpose of our study was to discover any evidence of myocardial anomalies in patients with exercise-induced ventricular premature beats.

METHODS

We examined 162 consecutive patients presenting palpitations and documented exercise-induced premature ventricular beats (PVBs) but no history or evidence of structural heart disease. Results were compared with 70 controls matched for gender and age. ECG-triggered, T2-weighted, fast spin echo triple inversion recovery sequences and late gadolinium enhancement were obtained as well as LV function and dimensions.

RESULTS

Structural anomalies in the myocardium and/or pericardium were present in 85 % of patients with exercise-induced PVBs. We observed a significant difference between patients with PVBs and controls in late gadolinium enhancement, that is 68 % presented subepicardial or midmyocardial lesions upon enhancement, whereas only 9 % of the controls did so (p < 0.0001). More patients presented pericardial enhancement (35 %) or pericardial thickening (27 %) compared to controls (21 % and 13 %, p < 0.0001). Myocardial oedema was present in 37 % of the patients and in only one control, p < 0.0001. Left ventricular ejection fraction did not differ between patients and controls (63.1 ± 7.9 vs. 64.7 ± 7.0, p = 0.13).

CONCLUSIONS

The majority of patients with exercise-associated premature ventricular beats present evidence of myocardial disease consistent with acute or previous myocarditis or myopericarditis.