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An abundance of literature describes physiological and pathological determinants of cardiac performance, building on the principles of excitation-contraction coupling. However, the mutual influencing of excitation-contraction and mechano-electrical feedback in the beating heart, here designated 'electromechanical reciprocity', remains poorly recognized clinically, despite the awareness that external and cardiac-internal mechanical stimuli can trigger electrical responses and arrhythmia. This review focuses on electromechanical reciprocity in the long-QT syndrome (LQTS), historically considered a purely electrical disease, but now appreciated as paradigmatic for the understanding of mechano-electrical contributions to arrhythmogenesis in this and other cardiac conditions. Electromechanical dispersion in LQTS is characterized by heterogeneously prolonged ventricular repolarization, besides altered contraction duration and relaxation. Mechanical alterations may deviate from what would be expected from global and regional repolarization abnormalities. Pathological repolarization prolongation outlasts mechanical systole in patients with LQTS, yielding a negative electromechanical window (EMW), which is most pronounced in symptomatic patients. The electromechanical window is a superior and independent arrhythmia-risk predictor compared with the heart rate-corrected QT. A negative EMW implies that the ventricle is deformed-by volume loading during the rapid filling phase-when repolarization is still ongoing. This creates a 'sensitized' electromechanical substrate, in which inadvertent electrical or mechanical stimuli such as local after-depolarizations, after-contractions, or dyssynchrony can trigger abnormal impulses. Increased sympathetic-nerve activity and pause-dependent potentiation further exaggerate electromechanical heterogeneities, promoting arrhythmogenesis. Unraveling electromechanical reciprocity advances the understanding of arrhythmia formation in various conditions. Real-time image integration of cardiac electrophysiology and mechanics offers new opportunities to address challenges in arrhythmia management.

An abundance of literature describes physiological and pathological determinants of cardiac performance, building on the principles of excitation–contraction coupling. However, the mutual influencing of excitation–contraction and mechano-electrical feedback in the beating heart, here designated ‘electromechanical reciprocity’, remains poorly recognized clinically, despite the awareness that external and cardiac-internal mechanical stimuli can trigger electrical responses and arrhythmia. This review focuses on electromechanical reciprocity in the long-QT syndrome (LQTS), historically considered a purely electrical disease, but now appreciated as paradigmatic for the understanding of mechano-electrical contributions to arrhythmogenesis in this and other cardiac conditions. Electromechanical dispersion in LQTS is characterized by heterogeneously prolonged ventricular repolarization, besides altered contraction duration and relaxation. Mechanical alterations may deviate from what would be expected from global and regional repolarization abnormalities. Pathological repolarization prolongation outlasts mechanical systole in patients with LQTS, yielding a negative electromechanical window (EMW), which is most pronounced in symptomatic patients. The electromechanical window is a superior and independent arrhythmia-risk predictor compared with the heart rate-corrected QT. A negative EMW implies that the ventricle is deformed—by volume loading during the rapid filling phase—when repolarization is still ongoing. This creates a ‘sensitized’ electromechanical substrate, in which inadvertent electrical or mechanical stimuli such as local after-depolarizations, after-contractions, or dyssynchrony can trigger abnormal impulses. Increased sympathetic-nerve activity and pause-dependent potentiation further exaggerate electromechanical heterogeneities, promoting arrhythmogenesis. Unraveling electromechanical reciprocity advances the understanding of arrhythmia formation in various conditions. Real-time image integration of cardiac electrophysiology and mechanics offers new opportunities to address challenges in arrhythmia management.

Aim Prolonged and dispersed left-ventricular (LV) contraction is present in patients with long-QT syndrome (LQTS). Electrical and mechanical abnormalities appear most pronounced in symptomatic individuals. We focus on the 'electromechanical window' (EMW; duration of LV-mechanical systole minus QT interval) in patients with genotyped LQTS. Profound EMW negativity heralds torsades de pointes in animal models of drug-induced LQTS. Methods and results We included 244 LQTS patients from three centres, of whom 97 had experienced arrhythmic events. Seventy-six matched healthy individuals served as controls. QT interval was subtracted from the duration of Q-onset to aortic-valve closure (QAoC) midline assessed non-invasively by continuous-wave echocardiography, measured in the same beat. Electromechanical window was positive in controls but negative in LQTS patients (22 +/- 19 vs. -43 +/- 46 ms; P

Sudden cardiac death (SCD) remains a daunting problem. It is a major public health issue for several reasons: from its prevalence (20% of total mortality in the industrialized world) to the devastating psycho-social impact on society and on the families of victims often still in their prime, and it represents a challenge for medicine, and especially for cardiology. This text summarizes the discussions and opinions of a group of investigators with a long-standing interest in this field. We addressed the occurrence of SCD in individuals apparently healthy, in patients with heart disease and mild or severe cardiac dysfunction, and in those with genetically based arrhythmic diseases. Recognizing the need for more accurate registries of the global and regional distribution of SCD in these different categories, we focused on the assessment of risk for SCD in these four groups, looking at the significance of alterations in cardiac function, of signs of electrical instability identified by ECG abnormalities or by autonomic tests, and of the progressive impact of genetic screening. Special attention was given to the identification of areas of research more or less likely to provide useful information, and thereby more or less suitable for the investment of time and of research funds. ? The Author 2014. Published by Oxford University Press on behalf of the European Society of Cardiology.

Sudden cardiac death (SCD) remains a daunting problem. It is a major public health issue for several reasons: from its prevalence (20% of total mortality in the industrialized world) to the devastating psycho-social impact on society and on the families of victims often still in their prime, and it represents a challenge for medicine, and especially for cardiology. This text summarizes the discussions and opinions of a group of investigators with a long-standing interest in this field. We addressed the occurrence of SCD in individuals apparently healthy, in patients with heart disease and mild or severe cardiac dysfunction, and in those with genetically based arrhythmic diseases. Recognizing the need for more accurate registries of the global and regional distribution of SCD in these different categories, we focused on the assessment of risk for SCD in these four groups, looking at the significance of alterations in cardiac function, of signs of electrical instability identified by ECG abnormalities or by autonomic tests, and of the progressive impact of genetic screening. Special attention was given to the identification of areas of research more or less likely to provide useful information, and thereby more or less suitable for the investment of time and of research funds.

Last year was the 20th anniversary of the first defibrillator implantation in a human being. Since then, the number of new defibrillator implants has gradually increased following an exponential curve. In 1998, nearly 50 000 new ICD implants were carried out worldwide. This tremendous increase was due to technological improvements in the device and the effectiveness of ICD therapy. Technological improvements in devices and leads included a gradual reduction in the size of the device, the introduction of the endocardial approach in 1988, the biphasic waveform and antitachycardia pacing in 1991, pectoral implantation in 1995, inclusion of DDD pacing in 1996 and finally, inclusion of DDDR and also atrial defibrillation in 1998. Efficacy assessment started with observational studies. In 1985, FDA approval for ICD implantation was obtained. Results of prospective randomized studies, which assessed the effectiveness of ICDs, were obtained in the late 1990s. The first reported trial was essentially an analysis of cost-effectiveness, which compared ICD implantation as first-choice therapy vs conventional strategy starting with antiarrhythmic drugs in postinfarct sudden death survivors. If drugs failed, the patient was treated with endocardial resection or a late defibrillator implant. The cost-effectiveness ratio, defined as costs per day of life, was significantly in favour of early ICD implantation. However, because the number of patients was relatively small, total mortality showed only a trend in favour of early ICD implantation.

This editorial refers to ‘Allele-specific RNA interference rescues the long-QT syndrome phenotype in human induced pluripotent stem cell cardiomyocytes’[†][1], by E. Matsa et al. , on page 1078 Congenital long-QT syndrome (LQTS) is a disorder of cardiac repolarization that manifests typically with ventricular arrhythmias such as torsades de pointes in patients with prolonged QT intervals in the ECG and structurally normal hearts. The known mutations affect genes encoding either subunits of cardiac ion channels or proteins involved in their regulation. Matsa and colleagues1 describe how they succeeded in using human induced pluripotent stem cell (hiPSC) technology not only to model a subtype of LQTS (LQT2), but also to evaluate a novel therapeutic approach using human cardiomyocytes derived from patient-specific hiPSCs. The authors generated cardiomyocytes from hiPSCs derived from a patient carrying a heterozygous mutation in the KCNH2 gene, corresponding to an A561T amino acid exchange in the KCNH2 -encoded protein hERG. Four hERG subunits co-assemble to form the pore of the ion channel generating the delayed rectifier potassium current IKr, an important determinant of the cardiac action potential duration. In accordance with the clinical phenotype of the patient, the hiPSC-derived cardiomyocytes displayed prolonged action potentials. The authors further demonstrated that, similar to other LQT2-causing ion channel mutations,2 the A561T mutation results in impaired ion channel trafficking: mutated subunits were not glycosylated properly and thus were retained in a perinuclear compartment instead of being integrated into the plasma membrane. Presumably due to co-assembly, the mutation also interfered with normal trafficking of the wild-type subunits in … [1]: #fn-2