Patients with adult myotonic dystrophy type 1 are at high risk for arrhythmias and sudden death. A severe abnormality on the ECG and a diagnosis of an atrial tachyarrhythmia predict sudden death. (ClinicalTrials.gov number, NCT00622453.)

T-wave alternans is a strong independent predictor of spontaneous ventricular arrhythmias or death. It performed as well as programmed stimulation and better than SAECG in risk stratifying patients for life-threatening arrhythmias.

Purpose of reviewMyotonic dystrophy type 1 (DM1) is a severe, progressive genetic disease that affects between 1 in 3,000 and 8,000 individuals globally. No evidence-based guideline exists to inform the care of these patients, and most do not have access to multidisciplinary care centers staffed by experienced professionals, creating a clinical care deficit.Recent findingsThe Myotonic Dystrophy Foundation (MDF) recruited 66 international clinicians experienced in DM1 patient care to develop consensus-based care recommendations. MDF created a 2-step methodology for the project using elements of the Single Text Procedure and the Nominal Group Technique. The process generated a 4-page Quick Reference Guide and a comprehensive, 55-page document that provides clinical care recommendations for 19 discrete body systems and/or care considerations.SummaryThe resulting recommendations are intended to help standardize and elevate care for this patient population and reduce variability in clinical trial and study environments.

Background-Thoracic spinal cord stimulation (SCS) is a promising therapy in treating refractory angina. This study was designed to investigate SCS with regard to the risk of arrhythmias during myocardial ischemia and its cardiac electrophysiological effects. Methods and Results-We studied 22 dogs with healed anterior myocardial infarction (MI) and superimposed heart failure (HF) induced by rapid ventricular pacing. SCS was applied at the dorsal T 1 -T 2 segments of the spinal cord (at 50 Hz, 0.2 ms) for 15 minutes. Transient (2-minute) myocardial ischemia was induced on 2 separate occasions (no SCS and SCS) to provoke ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation; VT/VF). Ischemic episodes were separated by 90 minutes, and dogs were randomly assigned to receive SCS or no SCS before the first or second ischemic episode. SCS reduced the occurrence of VT/VF from 59% to 23% when SCS was applied during transient myocardial ischemia (odds ratio, 0.36; 95% confidence interval, 0.1626 to 0.5646; Pϭ0.0009). SCS also decreased sinus rate by 7.5Ϯ14 bpm (Pϭ0.048), increased the PR interval by 11.1Ϯ14.7 ms (Pϭ0.009), and reduced systolic blood pressure by 9.8Ϯ13.6 mm Hg (Pϭ0.02). Conclusions-Thoracic

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Atrial flutter involving either clockwise or counterclockwise rotation around the tricuspid annulus utilizing the subeustachian isthmus has been well described. However, macroreentrant atrial circuits in atypical atrial flutter in patients who have not undergone previous surgery or without atrial disease are not well defined. We describe a patient without structural heart disease who presented with an atrial macroreentrant rhythm. Entrainment mapping demonstrated a critical isthmus within the coronary sinus. Activation mapping demonstrated double potential throughout the length of the coronary sinus with disparate activation sequences. A circuit involving the myocardium of the coronary sinus, exiting in the lateral left atrium, down the interatrial septum, and reentering into the coronary sinus was identified. Successful ablation of the rhythm was accomplished by a circumferential radiofrequency application within the coronary sinus.

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The severity of skeletal and cardiac myopathy in myotonic dystrophy correlates with age and CTG repeat length, suggesting a similar mechanism causing a time-dependent degenerative process.