Postextrasystolic repolarization changes of ventricular premature beats correlate with structural heart disease and suggest prognostic implications.

Ventricular premature beats (VPBs) can potentially lead to life-threatening arrhythmias, especially in patients with structural heart disease (SHD). However, identifying dangerous VPBs has always been a topic and challenge in clinical research. This study aimed to evaluate the relationship of postextrasystolic repolarization changes of VPBs with SHD and its possible additional prognostic value. 125 cases of frequent VPBs with SHD and 156 cases without SHD were included. VPBs were stratified selected from 24 h Holter recording according to the scale of heart rate. Average QTDV (difference value of QT interval between the first beat follow VPB with beats preceding VPB) and max QTDV were significantly longer in SHD group than that in the non-SHD group. For identifying patients with SHD, the best cutoff value were 19 ms for average QTDV (AUC = 0.931) and 29 ms for max QTDV (AUC = 0.910) respectively. For Tu morphology analysis, PT2 (postextrasystolic T wave amplitude change ≥2 mV), reversed T wave, and Pu (postextrasystolic u wave) change were all highly specific, but low sensitive as identification of SHD. Compared with average QTDV < 19 ms patients, average QTDV ≥ 19 ms patients had significantly larger left heart size and wores left cardiac function. The presence of non-persistent ventricular tachycardia runs was higher in average QTDV ≥ 19 ms group and positive Pu change group than that in control groups. The findings indicated that postextrasystolic repolarization changes of VPBs correlated with SHD and suggested potential value in prognosis asssessment.

Electrocardiogram abnormalities in chronic Chagas cardiomyopathy correlate with scar mass and left ventricular dysfunction as assessed by cardiac magnetic resonance imaging.

Electrocardiographic (ECG) abnormalities are frequently identified in Chronic Chagas cardiomyopathy (CCC) patients and advanced abnormalities are related to a worse prognosis. Cardiac Magnetic Resonance (CMR) can precisely assess ventricular systolic dysfunction and quantify myocardial fibrosis (MF), both identified as prognostic factors. We sought to investigate if ECG abnormalities in CCC patients were associated with more severe myocardial involvement as evaluated by CMR. METHODS: CCC patients with 12­lead ECG and CMR closely obtained were included. ECG analysis evaluated rhythm, presence, and type of intraventricular conduction disturbances (IVCD) and, ventricular premature beats (VPB). CMR short-axis cine and late gadolinium enhancement images were evaluated to obtain left and right ventricular ejection fractions and MF mass, respectively. Statistical significance was set in 5%. RESULTS: 194 CCC patients (98 women, 56 ± 14 years) were evaluated, and no IVCD was detected in 71. The most common IVCD was the association of right bundle branch block and left anterior fascicular block (RBBB+LAFB) in 58 patients, followed by isolated RBBB in 34, isolated LAFB in 17, and left bundle branch block (LBBB) in 14 patients. Of patients with no IVCD, 63% had MF and the burden of fibrosis (no IVCD - 7.4 ± 8.6%; RBBB - 6.6 ± 6.5%; p = 1.00), as well as left ventricular ejection fraction (LVEF) (no IVCD - 52 ± 14%; RBBB - 55 ± 10%; p = 1.00) were similar to patients with isolated RBBB. Left conduction system impairment was associated with lower LVEF (LAFB - 39 ± 15%; RBBB+LAFB- 41 ± 15%; and LBBB - 35 ± 15%; p < 0.001) and more MF (RBBB+LAFB - 12.2 ± 10.4%; LBBB - 10.6 ± 7.5%; and LAFB - 12.0 ± 7.0%; p < 0.001). The univariable model showed that the presence of MF was related to RBBB+LAFB (OR 5.0; p = 0.001) and VPB (OR 6.3; p = 0.014). After adjustment for age, gender, and different risk factors in a multivariable model, the same findings were still significantly related to CMR myocardial fibrosis (RBBB+LAFB OR 5.0; p = 0.002 / VPB OR 6.9; p = 0.015). CONCLUSIONS: ECG without IVCD does not exclude serious cardiac abnormalities in CCC, and isolated RBBB seems to have a benign course. The presence of VPB and left branch conduction impairment, especially LAFB associated with RBBB, indicate a more severe cardiac involvement.

Clinical Significance of Ventricular Premature Contraction Provoked by the Treadmill Test.

Background and Objectives: The treadmill test (TMT) is a predictive tool for myocardial ischemia. Recently, exercise-provoked ventricular premature contracture (VPC) during TMT was shown to have a relation with coronary artery disease and cardiovascular mortality. Therefore, we evaluate clinical correlates of exercise-provoked VPC and compare the predictive power for myocardial ischemia and cardiovascular events. Method: Data of 408 patients (≥18 years of age) who underwent TMT for work up of angina, palpitation, dyspnea, syncope, or arrhythmia between February 2015, and January 2016, were collected with consent at Samsung Medical Center, Seoul, Republic of Korea. Among total of 408 patients, 208 were excluded according to the previous history of PCI or CABG, previous MI, decreased left ventricular ejection fraction lower than 50%, arrhythmia that could affect ST-segment change on ECG. Results: Among 200 patients, 32 (16.0%) developed exercise-provoked VPC (21 patients in the exercise phase, 20 patients in the recovery phase). Of them, 20 patients (10.0%) showed positive TMT, and 4 patients (2.0%) underwent revascularization after TMT. Among 21 patients showing exercise phase VPC, 5 (23.8%) showed positive TMT results. In patients younger than 65 years, exercise phase VPC was associated with positive TMT (odds ratio 6.879, 1.458-32.453) considering demographics and previous medical history in multivariable analysis. Among the 20 patients showing recovery phase VPC, 2 (10.0%) underwent revascularization after TMT. In multivariable analysis, recovery phase VPC was associated with revascularization (odds ratio 9.381, 1.144-76.948) considering age, sex, BMI, and TMT result. Conclusion: VPC during the treadmill test was a useful predictor of myocardial ischemia in this study.

Antiarrhythmic drug effects on premature beats are partly determined by prior cardiac activation frequency in perfused guinea-pig heart.

NEW FINDINGS: What is the central question of this study? Can antiarrhythmic drug effects on repolarization, conduction time and excitation wavelength in premature beats be determined by prior cardiac activation frequency? What is the main finding and its importance? In premature beats induced after a series of cardiac activations at a slow rate, antiarrhythmics prolong repolarization but evoke little or no conduction delay, thus increasing the excitation wavelength, which indicates an antiarrhythmic effect. Fast prior activation rate attenuates prolongation of repolarization, while amplifying the conduction delay induced by drugs, which translates into the reduced excitation wavelength, indicating proarrhythmia. These findings suggest that a sudden increase in heart rate can shape adverse pharmacological profiles in patients with ventricular ectopy. ABSTRACT: Antiarrhythmic drugs used to treat atrial fibrillation can occasionally induce ventricular tachyarrhythmia, which is typically precipitated by a premature ectopic beat through a mechanism related, in part, to the shortening of the excitation wavelength (EW). The arrhythmia is likely to occur when a drug induces a reduction, rather than an increase, in the EW of ectopic beats. In this study, I examined whether the arrhythmic drug profile is shaped by the increased cardiac activation rate before ectopic excitation. Ventricular monophasic action potential durations, conduction times and EW values were assessed during programmed stimulations applied at long (S1 -S1 [basic drive cycle length] = 550 ms) and short (S1 -S1  = 200 ms) cycle lengths in perfused guinea-pig hearts. The premature activations were induced with extrastimulus application immediately upon termination of the refractory period. With dofetilide, a class III antiarrhythmic agent, a prolongation in action potential duration and the resulting increase in the EW obtained at S1 -S1  = 550 ms were significantly attenuated at S1 -S1  = 200 ms, in both the regular (S1 ) and the premature (S2 ) beats. With class I antiarrhythmic agents (quinidine, procainamide and flecainide), fast S1 -S1 pacing was found to attenuate the drug-induced increase in action potential duration, while amplifying drug-induced conduction slowing, in both S1 and S2 beats. As a result, although the EW was increased (quinidine and procainamide) or not changed (flecainide) at the long S1 -S1 intervals, it was invariably reduced by these agents at the short S1 -S1 intervals. These findings indicate that the increased heart rate before ectopic activation shapes the arrhythmic profiles by facilitating drug-induced EW reduction.

Elimination of Benign Ventricular Premature Beats or Ventricular Tachycardia with Catheter Ablation versus Two Different Optimal Antiarrhythmic Drug Treatment Regimens (Sotalol or Verapamil/Flecainide).

BACKGROUND: Symptomatic idiopathic ventricular arrhythmias (VA), including premature beats (VPB) and nonsustained ventricular tachycardia (VT) are commonly encountered arrhythmias. Although these VA are usually benign, their treatment can be a challenge to primary and secondary health care providers. Mainstay treatment is comprised of antiarrhythmic drugs (AAD) and, in case of drug intolerance or failure, patients are referred for catheter ablation to tertiary health care centers. These patients require extensive medical attention and drug regimens usually have disappointing results. A direct comparison between the efficacy of the most potent AAD and primary catheter ablation in these patients is lacking. The ECTOPIA trial will evaluate the efficacy of 2 pharmacological strategies and 1 interventional approach to: suppress the VA burden, improve the quality of life (QoL), and safety. HYPOTHESIS: We hypothesize that flecainide/verapamil combination and catheter ablation are both superior to sotalol in suppressing VA in patients with symptomatic idiopathic VA. STUDY DESIGN: The Elimination of Ventricular Premature Beats with Catheter Ablation versus Optimal Antiarrhythmic Drug Treatment (ECTOPIA) trial is a randomized, multicenter, prospective clinical trial to compare the efficacy of catheter ablation versus optimal AAD treatment with sotalol or flecainide/verapamil. One hundred eighty patients with frequent symptomatic VA in the absence of structural heart disease or underlying cardiac ischemia who are eligible for catheter ablation with an identifiable monomorphic VA origin with a burden ≥5% on 24-h ambulatory rhythm monitoring will be included. Patients will be randomized in a 1:1:1 fashion. The primary endpoint is defined as >80% reduction of the VA burden on 24-h ambulatory Holter monitoring. After reaching the primary endpoint, patients randomized to one of the 2 AAD arms will undergo a cross-over to the other AAD treatment arm to explore differences in drug efficacy and QoL in individual patients. Due to the use of different AAD (with and without ß-blocking characteristics) we will be able to explore the influence of alterations in sympathetic tone on VA burden reduction in different subgroups. Finally, this study will assess the safety of treatment with 2 different AAD and ablation of VA.

Narrow QRS complexes within left bundle branche block in a patient with chest pain.

We present the case of a patient with chest pain, palpitations, atrial fibrillation, left bundle branch block (LBBB) and occasional early narrow QRS complexes. An intracardiac study revealed rate-dependent LBBB with additional hidden rate-dependent slowing in the contralateral bundle branch, resulting in normalization of the early conducted QRS complexes.

An unusual ectopic ventricular rhythm in a young woman.

A case of a 22-year-old young pregnant woman with palpitations and near syncope is presented. Holter monitoring showed very frequent premature beats and runs of wide complex tachycardia, refractory to antiarrhythmic drugs. Electrophysiologic evaluation disclosed spontaneous automatism arising in an atriofascicular pathway. Differential diagnosis is discussed.

Dietary intervention with a specific micronutrient combination for the treatment of patients with cardiac arrhythmias: the impact on insulin resistance and left ventricular function.

BACKGROUND: Cardiac arrhythmias (CA) are very common and may occur with or without heart disease. Causes of these disturbances can be components of the metabolic syndrome (MetS) or deficits of micronutrients especially magnesium, potassium, B vitamins and coenzyme Q10. Both causes may also influence each other. Insulin resistance (IR) is a risk factor for diastolic dysfunction. One exploratory outcome of the present pilot study was to assess the impact of a dietary intervention with specific micronutrients on the lowering of IR levels in patients with CA with the goal to improve the left ventricular (LV) function. METHODS: This was a post hoc analysis of the randomized double blind, placebo-controlled pilot study in patients with CA (VPBs, SVPBs, SV tachycardia), which were recruited using data from patients who were 18-75 years of age in an Outpatient Practice of Cardiology. These arrhythmias were assessed by Holter ECG and LV function by standard echocardiography. Glucose metabolism was measured by fasting glucose, fasting insulin level and the Homeostasis Model Assessment of IR (HOMA-IR) at baseline and after 6 weeks of dietary supplementation. RESULTS: A total of 54 randomized patients with CA received either a specific micronutrient combination or placebo. Dietary intervention led to a significant decrease in fasting insulin ≥58 pmol/l (p = 0.020), and HOMA-IR (p = 0.053) in the verum group after 6 weeks. At the same time, parameters of LV diastolic function were improved after intervention in the verum group: significant reduction of LV mass index (p = 0.003), and in tendency both a decrease of interventricular septal thickness (p = 0.053) as well as an increase of E/A ratio (p = 0.051). On the other hand, the premature beats (PBs) were unchanged under verum. CONCLUSIONS: In this pilot study, dietary intervention with specific micronutrient combination as add-on to concomitant cardiovascular drug treatment seems to improve cardio metabolic health in patients with CA. Further studies are required. STUDY REGISTRATION: The study was approved by the Freiburg Ethics Commission International and was retrospectively registered with the U.S. National Institutes of Health Clinical Trials gov ID NCT 02652338 on 16 December 2015.

Postimplantation ventricular ectopic burden and clinical outcomes in cardiac resynchronization therapy-defibrillator patients: a MADIT-CRT substudy.

BACKGROUND: Frequent ventricular ectopy on preimplantation Holter has been associated with attenuated benefit from cardiac resynchronization therapy (CRT). However, it is unclear whether ectopic burden measured post-CRT implantation can be utilized to evaluate long-term prognosis. We aimed to describe the association between post-CRT implantation ectopic burden and subsequent risk of clinical outcomes. METHODS: At the 12-month follow-up visit, 24-hour Holter recordings were performed in 698 CRT-D patients from the MADIT-CRT study. The mean number of ventricular premature complexes (VPCs/hour) was calculated. High ectopic burden was defined as >10 VPCs/hour and low burden as ≤10 VPCs/hour. Multivariate Cox proportional hazards models were utilized to assess the association between 12-month ectopic burden and the risk of the end points of heart failure (HF) or death and ventricular tachyarrhythmias (VT/VF). RESULTS: At 12 months, 282 (40%) patients presented with low ectopic burden and 416 (60%) patients presented with high ectopic burden. The 3-year risk of HF/death and VT/VF was lower in patients with a low burden (7% and 8%) and significantly higher (25% and 24%) in patients with high burden. In multivariate analyses, patients with a high ectopic burden had approximately threefold increased risk of both HF/death (HR=2.76 [1.62-4.70], p < .001) and VT/VF (HR=2.79 [1.69-4.58], p < .001). CONCLUSION: In CRT-D patients with mild heart failure, high ectopic burden at 12-month follow-up was associated with a high 3-year risk of HF/death and VT/VF and threefold increased risk as compared to patients with low burden. Ectopic burden at 12 months may be a valuable approach for evaluating long-term prognosis.

Double ventricular response in dual AV nodal pathways mimicking interpolated premature beat.

Double ventricular response in dual atrioventricular (AV) nodal pathways can result in nonreentrant supraventricular tachycardia. Since this condition was first described in 1979, around 20 cases have been reported. Here, we present the case of a patient with a confirmed diagnosis of double ventricular response in dual AV nodal pathways resembling an interpolated premature beat who underwent successful radiofrequency ablation of the slow pathway.

A correlative study of myocardial infarction scar characteristics by DE-MR and the Lown's classification of ventricular premature beats.

OBJECTIVE: Correlation between myocardial infarction (MI) scar by cardiac magnetic resonance and the Lown's classification of ventricular premature beats (VPBs) is poorly understood. This study aims to investigate the correlation between the MI scar characteristics by delayed-enhancement magnetic resonance imaging (DE-MRI) and the Lown's classification of VPBs. METHODS: Sixty-five patients, in the convalescence stage and consolidation phase of MI, were included in this retrospective study. All patient were divided into VPBs group (n = 39) and non-VPBs group (n = 26 patients) according to the clinical diagnostic criteria of Universal Definition of MI scar. VPBs patients were assigned to Lown's I-II group and Lown's III-IV subgroup in accordance with the Lown classification criteria. Cardiac function parameters and MI scar characteristics were detected by cardiac magnetic resonance (CMR) and DE-MRI, respectively. RESULTS: Lown's classification was negatively correlated with left ventricular ejection fraction (LVEF), peak ejection rate (PER) and peak filling rate (PFR) (-0.724, -0.628, -0.559), and positively correlated with MI area, MI integral, MI segments number and left ventricular end systolic volume (LVESV) (0.673, 0.655, 0.586, and 0.514), respectively.CONCLUSIONSThe study indicated that MI area and MI integral were strongly associated with Lown's classification.

Slow antegrade excitation and delayed retrograde activation through an "inexcitable zone": A basis for arrhythmia formation in infarcted myocardium ex vivo.

INTRODUCTION: The electrophysiologic mechanism for rate-dependent PVBs associated with double potentials (DPs) was investigated in infarcted canine hearts using bipolar and intracellular microelectrode recordings. METHODS AND RESULTS: Dogs exhibiting rate-related ventricular ectopic beats (coupling interval, 390 ± 54 milliseconds) during sinus rhythm or atrial pacing were studied 4-5 days (N = 63) or 25 days (N = 16) following anterior descending coronary artery ligation. Sites of DP and rate-dependent arrhythmia formation were identified in vivo using bipolar recordings for subsequent ex vivo studies. Rate-dependent conduction delays with increasing duration isoelectric intervals representing very slow conduction were observed at sites of DP formation, frequently provoking both manifest and concealed reentry (non-stimulated beats) over a narrow range of paced cycle lengths. Both slow antegrade and retrograde activation across an inexcitable gap (reflection) were integral components of extrasystole formation. Retrograde reflection to a region of very slow conduction (mid-potential) during antegrade activation was routinely observed at 4-5 days (42 of 63 preparations, 67%) and 25 days (22 of 26 preparations, 85%) postcoronary artery ligation. Reflection and premature re-activation of the proximal site was then observed in 6 of 63 (9%), and 3 of 26 preparations (12%). CONCLUSION: The present experiments demonstrate DP formation and rate-dependent constant-coupled late epicardial premature beats in infarcted dog hearts. Microelectrode recordings at DP sites demonstrating prolonged isoelectric intervals display very slow conduction preceding distal activation and "reentrant" re-activation of more proximal sites, representing reflection as an arrhythmia mechanism in ischemically injured epicardium during subacute myocardial infarction.

Slow conduction through an arc of block: A basis for arrhythmia formation postmyocardial infarction.

INTRODUCTION: The electrophysiologic basis for characteristic rate-dependent, constant-late-coupled (390 + 54 milliseconds) premature ventricular beats (PVBs) present 4-5 days following coronary artery occlusion were examined in 108 anesthetized dogs. METHODS AND RESULTS: Fractionated/double potentials were observed in injured zone bipolar and composite electrograms at prolonged sinus cycle lengths (1,296 ± 396 milliseconds). At shorter cycle lengths, conduction of the delayed potential decremented, separating from the initial electrogram by a progressively prolonged isoelectric interval. With sufficient delay of the second potential following an isoelectric interval, a PVB was initiated. Both metastable and stable constant-coupled PVBs were associated with Wenckebach-like patterns of delayed activation following an isoelectric interval. Signal-averaging from the infarct border confirmed the presence of an isoelectric interval preceding the PVBs (N = 15). Pacing from the site of double potential formation accurately reproduced the surface ECG morphology (N = 15) of spontaneous PVBs. Closely-spaced epicardial mapping demonstrated delayed activation across an isoelectric interval representing "an arc of conduction block." Rate-dependent very slow antegrade conduction through a zone of apparent conduction block (N = 8) produced decremental activation delays until the delay was sufficient to excite epicardium distal to the original "arc of conduction block," resulting in PVB formation. CONCLUSION: The present experiments demonstrate double potential formation and rate-dependent constant-coupled late PVB formation in infarcted dog hearts. Electrode recordings demonstrate a prolonged isoelectric period preceding PVB formation consistent with very slow conduction (<70 mm/s) across a line of apparent conduction block and may represent a new mechanism of PVB formation following myocardial infarction.

Supraventricular premature beats and risk of new-onset atrial fibrillation in coronary artery disease.

INTRODUCTION: The significance of premature atrial contraction (PAC) count and supraventricular runs (SVR) for the risk of development of new-onset atrial fibrillation (AF) in patients with coronary artery disease (CAD) is not well established. METHODS: The Innovation to Reduce Cardiovascular Complications of Diabetes at the Intersection (ARTEMIS) study cohort consisted of 1,946 patients with CAD who underwent clinical and echocardiographic examinations, 24-hour ambulatory ECG monitoring, and laboratory tests. After excluding patients who were not in sinus rhythm at baseline or were lost from the follow-up, the present study included 1,710 patients. SVR was defined as at least four PACs in a row with a duration <30 seconds. RESULTS: During a follow-up for an average 5.6 ± 1.5 years, new-onset AF was identified in 143 (8.4%) patients. In the univariate analysis, both SVR and PAC count were associated with the development of new-onset AF. When SVR and PAC count were adjusted with the established AF risk markers of the modified CHARGE-AF model in the Cox multivariate regression analysis, both parameters remained significant predictors of the occurrence of new-onset AF (HR = 2.529, 95 % CI = 1.763-3.628, P ˂ 0.001 and HR = 8.139 for ≥1,409 PACs [the fourth quartile] vs. ≤507 PACs [the first quartile], 95 % CI = 3.967-16.696, P ˂ 0.001, respectively). Together these parameters improved the C-index of the established AF risk model from 0.649 to 0.718, P < 0.001. CONCLUSION: Including SVR and PAC count to the established AF risk model improves the discrimination accuracy in predicting AF in patients with CAD.

[Treatment for ventricular arrhythmias in the absence of structural heart disease: from guidelines to clinical practice]. / Lechenie zheludochkovykh aritmii v otsutstvie strukturnoi patologii serdtsa: ot rekomendatsii k klinicheskoi praktike.

AIM: To determine criteria for choosing management tactics in patients with ventricular arrhythmias (VA) in the absence of structural heart disease from the point of view of physicians and patients in clinical practice and to compare the immediate results of antiarrhythmic drug therapy (ADT) and radiofrequency ablation (RFA) with the trends in arrhythmic syndrome in the non-treatment group. SUBJECTS AND METHODS: Examinations were made in 90 patients (23 men and 67 women) (mean age, 44 (31; 57) years) with VA in the absence of structural heart disease. Preference was given to RFA (n = 32 (36%)), ADT (n = 37 (41%)), and follow-up tactics (n = 21 (23%)). At baseline and 1 month, Holter ECG monitoring was done; quality of life (QOL) was assessed; and anxiety and depression levels were detected using the SF-36 and HADS questionnaires. In addition, 71 physicians were surveyed about their preferences to the treatment of VA in individuals without structural heart disease. RESULTS: In the total group of patients, VA was unambiguously accompanied by the symptoms only in 47%. The signs of anxiety and depression were identified in 41 and 14% of cases, respectively. The efficiency of RFA was comparable to that of ADT (p > 0.1): a positive antiarrhythmic effect was observed in 71.9% of the patients in the RFA group and in 67.6% in the ADT group. During one month, 38.1% of the patients in the follow-up group showed a spontaneous substantial reduction in the number of ventricular premature beats (VPBs) or disappearance of unstable ventricular tachycardia (UVT), which met the criteria for a positive effect. At baseline, the QOL indicators on a social functioning scale in the RFA group were worse than those in the ADT group. At the same time, most QOL indicators in the patients who have chosen a wait-and-see tactic were significantly higher than those in the RFA and ADT subgroups. The patients treated with ethacyzin in the ADT group more frequently achieved a positive effect. In the interviewed physicians' opinion, the choice of a tactic depended on the impact of arrhythmia on health status (68%), the number of VPBs per day (61%), and the presence of UVT (56%). RFA or ADT was most often recommended when there were 10,000-15,000 or more VPBs per day ((49 and 35% of the respondents, respectively). 46.5% of the respondents stated that ß-blockers were the drug of choice for idiopathic frequent VPBs. Only 30% of the respondents considered it appropriate to restrict to a follow-up in the presence of asymptomatic VPBs. CONCLUSION: Patient management in clinical practice generally complies with the current guidelines; however, much importance is attached to the severity of arrhythmia (the number of VPBs per day, the presence of UVT) in addition to the presence of symptoms. In the opinion of most physicians, the initiation of treatment is justified when there are 10,000-15,000 and more per day. QOL assessment may be promising in choosing the optimal management tactics for these patients. Treatment should not be initiated immediately in patients with a high level of QOL, especially in those with arrhythmia lasting less than 12 months, by taking into account that there can be a spontaneous improvement in 38% of cases within the next month. The immediate results of ADT and RFA are comparable in patients with VA in the absence of structural heart disease. The Class IC antiarrhythmic drug ethacyzin is the most effective agent that ensures positive changes in arrhythmic syndrome in 66.7% of cases with the rate of side effects being in 17.8%.

PULSE-SMART: Pulse-Based Arrhythmia Discrimination Using a Novel Smartphone Application.

BACKGROUND: Atrial fibrillation (AF) is a common and dangerous rhythm abnormality. Smartphones are increasingly used for mobile health applications by older patients at risk for AF and may be useful for AF screening. OBJECTIVES: To test whether an enhanced smartphone app for AF detection can discriminate between sinus rhythm (SR), AF, premature atrial contractions (PACs), and premature ventricular contractions (PVCs). METHODS: We analyzed two hundred and nineteen 2-minute pulse recordings from 121 participants with AF (n = 98), PACs (n = 15), or PVCs (n = 15) using an iPhone 4S. We obtained pulsatile time series recordings in 91 participants after successful cardioversion to sinus rhythm from preexisting AF. The PULSE-SMART app conducted pulse analysis using 3 methods (Root Mean Square of Successive RR Differences; Shannon Entropy; Poincare plot). We examined the sensitivity, specificity, and predictive accuracy of the app for AF, PAC, and PVC discrimination from sinus rhythm using the 12-lead EKG or 3-lead telemetry as the gold standard. We also administered a brief usability questionnaire to a subgroup (n = 65) of app users. RESULTS: The smartphone-based app demonstrated excellent sensitivity (0.970), specificity (0.935), and accuracy (0.951) for real-time identification of an irregular pulse during AF. The app also showed good accuracy for PAC (0.955) and PVC discrimination (0.960). The vast majority of surveyed app users (83%) reported that it was "useful" and "not complex" to use. CONCLUSION: A smartphone app can accurately discriminate pulse recordings during AF from sinus rhythm, PACs, and PVCs.

Exercise and Arrhythmias: A Double-Edged Sword.

Ample evidence indicates that moderate regular exercise is beneficial for both normal individuals and patients with cardiovascular (CV) disease. However, intense and strenuous exercise in individuals with evident or occult underlying CV abnormalities may have adverse effects with provocation and exacerbation of arrhythmias that may lead to life-threatening situations. Both of these aspects of exercise-induced effects are herein reviewed.

Sinus node injury during adjunctive superior vena cava isolation in a patient with triggered atrial fibrillation.

INTRODUCTION: Atrial fibrillation is the most common sustained heart arrhythmia. Premature beats arising from foci other than pulmonary veins have been related to its pathogenesis. METHODS AND RESULTS: A 64-year-old female underwent superior vena cava (SVC) isolation after triggers were identified originating from the SVC following pulmonary vein isolation; immediately after SVC isolation, she developed junctional rhythm with symptomatic hypotension requiring emergent management. Apical motion abnormalities were noticed in the echocardiography suggesting stress-induced cardiomyopathy which resolved 48 hours later. Although received a dual chamber pacemaker, intact sinus node function returned 2 weeks later. CONCLUSION: Superior vena cava isolation in those with trigger mediated atrial fibrillation following pulmonary vein isolation (PVI) is performed to enhance long-term outcomes. Sinus node injury has been related previously to this procedure. We present the first case of time course of recovery of sinus node function, injured during SVC isolation.

Successful ablation of frequent atrial premature beats from non-coronary aortic cusp with remote magnetic navigation.

A 59-year-old female with structurally normal heart was admitted to our hospital for treatment of highly symptomatic, drug refractory atrial premature beats (APB). ECG revealed atrial parasystolic trigeminy. The arrhythmogenic focus was mapped and ablated using magnetic remote navigation and 3D electroanatomical mapping system. To our knowledge, this is the first report on successful ablation of frequent APBs in the non-coronary aortic cusp.

Reappraisal of cardiac magnetic resonance imaging in idiopathic outflow tract arrhythmias.

INTRODUCTION: Because of prognostic and therapeutic implications, the distinction between idiopathic right ventricular (RV) outflow tract (iRVOT) and arrhythmogenic RV cardiomyopathy (ARVC) is clinically important. Over the last 2 decades multiple reports have identified RV abnormalities using CMR in patients with idiopathic VT, suggesting a link between these arrhythmias and ARVC. The purpose of this study was to assess for structural abnormalities in patients with iRVOT tachycardia using contemporary cardiac magnetic resonance (CMR) imaging. METHODS AND RESULTS: CMR was performed in 46 patients with iRVOT tachycardia and 16 normal controls, with quantitative evaluation of RV and left ventricular volumes and function, as well as assessment of myocardial fat and scar. iRVOT patients were similar to controls with respect to RV end-diastolic volumes (81 ± 19 mL/m(2) vs. 79 ± 18 mL/m(2) , P = 0.77) and RV ejection fraction (57 ± 8% vs. 59 ± 7%, P = 0.31). The prevalence of RV chamber dilation, defined using ARVC major task force criteria, was uncommon among iRVOT patients (9%) and controls (7%; P = 1.0). Regional RV wall motion abnormalities were present in 2 iRVOT patients who had concomitant RV dilation or dysfunction. CMR tissue characterization demonstrated absence of both myocardial scar and fat infiltration in all patients and controls. CONCLUSIONS: In patients with the clinical diagnosis of iRVOT tachycardia, CMR reveals RV structure, function, and myocardial tissue characteristics similar to normal controls. These findings suggest that the vast majority of patients with RVOT arrhythmias have a primary electrical disorder that is not a forme-fruste of ARVC.