Cardiac resynchronization therapy in patients with heart failure and narrow QRS complexes (≤ 130 ms): role of speckle tracking echocardiography and different interventricular (VV) pacing intervals.

PURPOSE: Response to cardiac resynchronization therapy (CRT) in patients with heart failure with reduced ejection fraction (HFrEF) depends on the degree of correction of interventricular (VV) electromechanical dyssynchrony between the left and right ventricles (LV, RV). Wide (> 130 ms [ms]) QRS interval is used as a qualifying ECG parameter for CRT device implantation. In this study, we aimed to evaluate myocardial strain (S) and myocardial strain patterns (SP) and strain rate (SR) by speckle tracking echocardiography (STE) and mechanical characteristics at different VV intervals in acute settings and long-term outcome from "sequential LV-RV" pacing programming in patients with narrow (< 130 ms) and wide (> 130 ms) QRS complexes as a basis for extending CRT in select patients with narrow QRS. METHODS: From a previously established cohort of patients who had undergone CRT device implantation, we identified patients with narrow (< 130 ms) and wide (> 130 ms) QRS complexes, groups A and B respectively. In all patients, we assessed myocardial SP and SR by STE, and mechanical characteristics at VV intervals: "LV Off," "VV0," "VV60," and "RV Off" to provide "RV-only," "simultaneous BiV," "sequential LV-RV," and "LV-only" pacing in the acute settings, and subsequently long-term clinical outcomes with CRT devices programmed to VV60. We compared acute STE characteristics and long-term clinical outcomes between the groups. RESULTS: The study cohort comprised 271 patients (age 69.2 ± 10.3 years [mean ± SD], male-60%). Group A (n = 69) and group B (n = 202) were well matched for the clinical variables, including distribution of patients with ischemic versus non-ischemic cardiomyopathies. QRS width and left ventricular ejection fraction (LVEF) in groups A and B were 120.1 ± 12.3 ms and 152.1 ± 12.9 ms (p < 0.05), and 22.3 ± 9.4%, and 23.3 ± 10.2% (p = not significant [NS]). With VV0, VV60, and LV-only timings, corresponding LVEF rates in the acute settings were 31.45 ± 10.9%, 40.08 ± 8.3%, and 44.32 ± 7.98% (p < 0.01) in group A, and 38.94 ± 8.5%, 46.91 ± 7.33%, and 49.9 ± 8.94% (p < 0.01) in group B, and accounted for similar incremental percentage increase in LVEF compared to baseline in group A (43.2 ± 51.7%, 80.9 ± 61.4%, and 93.4 ± 65.6% respectively) and group B (67.3 ± 82.0%, 100.6 ± 94.3%, and 112.9 ± 95.7% respectively) (p = NS). Abnormal SP and SR were consistently observed with RV pacing that improved with VV60 and LV-only pacing in both groups. Strain scores at different VV timings were similar between the groups (p = NS). At 1-year follow-up, LVEF improved from 22.4 ± 8.0% to 39.8 ± 11.5% (p ≤ 0.001) for the total cohort with similar increments observed in both groups (p = NS). There were fewer NYHA III-IV class patients at 1 year in both groups. CONCLUSIONS: Comparable myocardial SP and SR characteristics and LVEF improvement with VV60 and LV-only pacing in the acute setting and long-term outcome of CRT by "sequential LV-RV" pacing seen in patients with both narrow and wide QRS duration suggest that CRT device implantation may be justified in select patients with HFrEF and narrow QRS duration (< 130 ms) who have demonstrable dyssynchrony and abnormal myocardial SP and SR characteristics.

Myocardial strain characteristics at different interventricular pacing timings: implications for device programming and long-term clinical outcomes in patients with cardiac resynchronisation therapy.

AIMS: Response to cardiac resynchronisation therapy (CRT) in patients with heart failure depends on the degree of correction of electromechanical dyssynchrony between the left and right ventricles (LV, RV). It is not known whether chronic programming of interventricular (VV) intervals based on characterisation of myocardial strain at different pacing intervals performed acutely would have better long-term clinical outcomes. We hence aimed to evaluate this relationship between speckle tracking strain patterns and rates at different VV intervals and long-term clinical outcomes of programmed VV pacing in patients with CRT in a prospective, longitudinal follow-up study. METHODS: We assessed echocardiographic effects, myocardial strain patterns and rates in acute settings at VV intervals; 'LV Off', 'VV0', 'VV60' and 'RV Off' to provide 'RV-only', 'simultaneous BiV', 'sequential LV-RV' and 'LV-only' pacing respectively in 338 patients (age, 67.5 ± 10.3 years; male, 70%) with CRT. Thereafter, devices were programmed chronically to VV60, and long-term clinical outcomes were assessed. RESULTS: With VV0, VV60 and LV only pacing, LVEF improved to 33.6 ± 12.3%, 40.0 ± 11.4% and 42.6 ± 11.2%, respectively, from 23.7 ± 10.2% at baseline (p < .001). Incremental improvement in strain occurred with VV0, VV60 and LV only pacing; greatest with LV only pacing. At 1 year, 23% patients had NYHA III-IV compared to 96% at baseline (p < .001). CONCLUSIONS: In patients with CRT, different VV timings show significant differences in acute myocardial strain patterns and rates, and LVEF. These changes are markedly favourable with LV-only and sequential LV-RV pacing, the latter with chronic programming also results in long-term clinical improvement.

Coronary intervention and arteria lusoria-Not simple as it may seem.

We reviewed the letter from Dr. Walter W. Woody and would like to thank him for showing his interest in our article and providing his opinion and point of view. However, we respectfully disagree with few points that have been raised. Switching to a femoral approach was considered to be a safer alternative for percutaneous intervention due to the presence of arteria lusoria. Risks and possible complications would include increased contrast use, increased radiation exposure, aortic dissection and even cerebral stroke, all of which have been reported extensively in literature. One single procedural methodology cannot be applied to a particular clinical scenario, whether simple or challenging. We have multiple different catheters and multiple different interventional approaches at our disposal to help and guide us through a case, in the best interest of the patient.

Incidental finding of arteria lusoria during transradial coronary catheterization: Significance in interventional cardiology.

Arteria lusoria is the most common anomaly of the aortic arch with an incidence of 0.5%-2.5%. It is mostly diagnosed incidentally while performing imaging for evaluation of other unrelated medical conditions. The aberrant right subclavian artery arises beyond the origin of the left subclavian artery from the aortic arch. This results in a complex right-subclavian-aortic anatomy which leads to difficulty in transradial coronary angiography. This can lead to prolonged procedure time and increased use of catheters by unaware interventionists. This is even more important if this is encountered in the setting of an acute myocardial infarction. Our review takes into account clinical significance of this uncommon anomaly in the field of interventional cardiology.

Pacing to prevent atrial fibrillation.

PURPOSE OF REVIEW: Pacemakers are frequently implanted in patients with atrial fibrillation. Many patients with pacemakers also develop atrial fibrillation. Over a period of time, through many studies on different pacing modes, sites, and algorithms, significant insights have been gained in the field of treatment and prevention of atrial fibrillation. The purpose of this review is to discuss some aspects of the scientific basis, current standards and possible future research related to cardiac pacing for prevention of atrial fibrillation. RECENT FINDINGS: Trials involving pacing at the alternative pacing site per se or in combination with specific algorithms for prevention of atrial fibrillation have not shown consistent results. Recently, a new generation of antitachycardia pacing therapies has brought on a new optimism with promising outcome data of reduction in permanent atrial fibrillation, cardiovascular hospitalizations, and mortality. SUMMARY: Multiple trials and clinical observational studies of different pacing methods and algorithms, with the exception of newer therapies in conjunction with atrial pacing algorithms, have not been shown to prevent atrial fibrillation. Hence, while permanent pacing is indicated for sinus node dysfunction and conduction abnormalities in patients with or without atrial fibrillation, the prevailing data in the literature does not support implantation of a permanent pacemaker for prevention of atrial fibrillation per se.

Early repolarisation and J wave syndromes.

J wave syndrome has emerged as a significant cause of Idiopathic ventricular fibrillation (IVF) responsible for sudden cardiac death. A large body of data is now available on genesis, genetics and ionic mechanisms of J wave syndromes. Two of these viz., Early repolarization syndrome (ER) and Brugada syndrome (BrS) are fairly well characterized enabling correct diagnosis in most patients. The first part of repolarization of ventricular myocardium is governed by Ito current i.e., rapid outward potassium current. The proposed mechanism of ventricular fibrillation (VF) and ventricular tachycardia (VT) storms is the faster Ito current in the epicardium than in the endocardium results in electrical gradient that forms the substrate for phase 2 reentry. Prevention of Ito current with quinidine supports this mechanism. Majority of ER patterns in young patients are benign. The key issue is to identify those at increased risk of sudden cardiac death. Association of both ER syndrome and Brugada syndrome with other disease states like coronary artery disease has also been reported. Individuals resuscitated from VF definitely need an implantable cardiac defibrillator (ICD) but in others there is no consensus regarding therapy. Role of electrophysiology study to provoke ventricular tachycardia or fibrillation is not yet well defined. Radiofrequency ablation of epicardial substrate in right ventricle in Brugada syndrome is also under critical evaluation. In this review we shall discuss historical features, epidemiology, electrocardiographic features, ionic pathogenesis, clinical features and current status of proposed treatment of ER and BrS.

J Wave Syndrome: Clinical Diagnosis, Risk Stratification and Treatment.

J wave syndrome has emerged from a benign electrocardiographic abnormality to a proarrythmic state and a significant cause of idiopathic ventricular fibrillation responsible for sudden cardiac death. Electrical genesis, genetics and ionic mechanisms of J wave syndromes are active areas of research. Typically two of these viz., Early repolarization syndrome (ER) and Brugada syndrome (BrS) are fairly well characterized enabling correct diagnosis in most patients. In early repolarization syndrome, J waves are seen in inferior (2,3, avF) or lateral leads (V4, V5, V6), while in Brugada syndrome they are best seen in right precordial leads (V1-V3). The first part of repolarization of ventricular myocardium is governed by Ito current i.e., rapid outward potassium current. The proposed mechanism of ventricular fibrillation (VF) and ventricular tachycardia (VT) storms is faster Ito current in the epicardium than in the endocardium resulting in electrical gradient that forms the substrate for phase 2 re-entry. Prevention of Ito current with quinidine supports this mechanism. Morphological features of benign variety of J wave syndrome and malignant/ proarrythmic variety have now been fairly well characterized. J waves are very common in young, athletes and blacks; risk stratification for VF/sudden cardiac death (SCD) is not easy. Association of both ER syndrome and Brugada syndrome with other disease states like coronary artery disease is being reported frequently. Those with ECG abnormality as the only manifestation are difficult to manage. Certain ECG patterns are more proarrythmic. Individuals resuscitated from VF definitely need an implantable cardiac defibrillator (ICD) but in others there is no consensus regarding therapy. Role of electrophysiology study to provoke ventricular tachycardia or fibrillation is not yet well defined. Radiofrequency ablation of epicardial substrate in right ventricle in Brugada syndrome is reported and is also under critical evaluation. In this review we shall discuss some interesting historical features, epidemiology, electrocardiographic features, and ionic mechanisms on pathogenesis, clinical features, risk stratification and treatment issues in J wave syndromes. Brugada syndrome is not discussed in this review.

Simultaneous ST-segment elevation in inferior and precordial leads following ingestion of a lethal dose of desipramine: a novel Brugada-like EKG pattern.

The typical Brugada electrocardiographic (EKG) pattern includes ST-segment elevation in the right precordial leads (V1-V3) associated with right bundle branch block (rSR') like morphology. Recently, a Brugada-like EKG pattern with ST-segment elevation in inferior leads called the "Brugada variant" has been reported. We report a case of simultaneous typical and variant Brugada EKG patterns with ST-segment elevation in the inferior as well as the precordial leads following ingestion of a lethal dose of desipramine.

Atrial fibrillation: current concepts.

Atrial fibrillation (AF) is the most common arrhythmia which is a focus of newer modalities of treatment, especially ablation techniques using innovative mapping techniques. Its incidence and prevalence increases with aging and presence of structural heart disease, the latter being less than 1% prior to age 40, rising to 8% at age 80. Concomittant morbidity and excessive mortality is related to the increased incidence of stroke and congestive heart failure. Once developed in a clinical setting, it tends to either persist or recur. Pharmacotherapy to control rate or rhythm tends to have a secondary failure, and therefore there is a growing interest in ablation techniques. The use of anticoagulation is also associated with bleeding risks and therefore the management of AF needs to be individualized in every patient. In this article, we shall be discussing clinical types of AF, etiology, the mechanism of genesis, symptoms, complications and approach to treatment in various clinical scenarios.