Cardiac resynchronization therapy (CRT) was originally established as an effective treatment for patients with systolic heart failure (HF) with New York Heart Association Class III–IV symptoms, reduced left ventricular ejection fraction and prolonged QRS duration ≥120 ms. Subsequent studies expanded the role of CRT to the treatment of patients with mildly symptomatic HF as these patients experienced similar improvement in clinical symptoms and reverse remodeling of the left ventricle. These clinical trial results were incorporated into the 2013 guidelines on cardiac pacing and CRT from the European Society of Cardiology and the 2012 American College of Cardiology Foundation/American Heart Association/Heart Rhythm Society Focused Update on Device-based Therapy of Cardiac Rhythm Abnormalities. Additional data from careful post hoc and substudy analyses as well as long-term follow-up of the original study cohorts have been performed. These results attempt to identify subgroups more likely to benefit from CRT, to define the association between response and QRS morphology/duration and to demonstrate the sustained benefit of CRT in this population. More importantly, these results highlight that patients with mildly symptomatic HF who respond to CRT not only have improvement in clinical symptoms but also receive a therapy that may prevent or delay progression of HF. A review of the clinical trials in mildly symptomatic HF and the results of subsequent post hoc analysis are summarized herein.

Pulmonary vein isolation (PVI) is the established cornerstone in catheter ablation for atrial fibrillation (AF). The traditional point-to-point ablation by focal radiofrequency (RF) catheter to achieve PVI was technically challenging, and the outcome remained suboptimal despite advancement in three-dimensional electroanatomical mapping systems and steerable sheaths. Different catheter designs including contact force, balloon-based catheters with other energy sources (cryothermal and laser energies), and circular RF catheters have been developed to make the ablation procedure more user-friendly and PVI more durable. Adjunctive techniques including detection of dormant conduction by adenosine triphosphate injection and pace-capture-guided ablation have also been studied to improve the durability of PVI and thus reduce the AF recurrence rate.

Atrial fibrillation is independently associated with an increased risk of thromboembolic stroke. While anticoagulants decrease this risk, they also carry a substantial risk of bleeding. Most left atrial thrombi arise from the left atrial appendage (LAA), which has led to several investigations into surgical and percutaneous methods of LAA exclusion for stroke reduction. The PubMed database was queried, and over 400 articles were considered for inclusion in this review. Of the surgical methods of LAA exclusion, complete excision is the most effective. Other methods, including ligation and stapling, may be incomplete and associated with left atrial thrombus formation. Surgical LAA exclusion has been commonly performed during mitral valve surgery although it has not been shown to prevent stroke in many retrospective studies. In patients unable to take warfarin, several percutaneous LAA exclusion devices have been studied, including the PLAATO system, Amplatzer Cardiac Plug (ACP), Watchman device, and Lariat. Both the ACP and Watchman have shown a significant stroke reduction and improved procedural safety with greater experience. The Lariat ligates the LAA using a combined endocardial and epicardial approach but is currently associated with substantial procedural risks. With better patient selection for the different options of LAA exclusion, thromboembolic stroke protection can be maximized with fewer complication risks.

Background: Cardiac contractility modulation (CCM) has been used in patients with heart failure and normal QRS duration to improve exercise tolerance and quality of life. The safety and efficacy of CCM have been previously tested in moderate to severe heart failure patients with various etiologies in the western population. However, limited data are available on the safety and efficacy of CCM in Chinese patients with dilated cardiomyopathy and heart failure. Methods: Eight patients with dilated cardiomyopathy were prospectively enrolled to receive CCM implants from 5 hospitals in China. All patients had the New York Heart Association (NYHA) functional class III and IV heart failure, with left ventricular ejection fraction (LVEF) ≤35%, and QRS ≤ 120 ms. All patients were followed up at the 3^rd and 6^th month. Evaluation included the NYHA functional class, 6-min hall walk test (6MHW), Minnesota Living with Heart Failure (MLWHF) Questionnaire, and CCM parameters. Results: CCM was successfully implanted in all eight patients (50 ± 11 years, 6 men), and no device-related complications were observed in all patients at 3- and 6-month follow-up besides one patient voluntarily received heart transplantation at the 2^nd month after CCM implantation and died from intracerebral hemorrhage during the perioperative period. Compared with baseline, the NYHA functional class (ΔNYHA: −1.0–−3.0, P= 0.016), the MLWHF quality of life scores (ΔMLWHF: −21.1 ± 17.5, P= 0.019), and 6MHW (Δ6MHW: 207.4 ± 202.5 m, P= 0.035) were significantly improved at 3-month follow-up. No significant change was observed in LVEF (ΔLVEF: −0.5%, 95% CI: −2.0%–12%, P= 0.813). All of these evaluations at 6-month follow-up were similar to those observed at 3-month, and no further improvement were observed from 3- to 6-month follow-up in the NYHA functional class (ΔNYHA 0; 0–1.0, P= 0.999), 6MHW (Δ6MHW: 39.2 ± 70.4 m, P= 0.231), MLWHF quality of life score (ΔMLWHF: 2.7 ± 3.9, P= 0.158), and LVEF (ΔLVEF: 2.0%, 95% CI: −2.0%–7.0%, P= 0.313). Conclusions: CCM might be a new choice of device treatment for Chinese patients with nonischemic cardiomyopathy and heart failure if they have normal QRS duration.

Background: Fragmented QRS (fQRS) complex on a 12-lead electrocardiogram (ECG) is reportedly associated with myocardial scar or fibrosis in patients with structural heart disease. In healthy persons, however, the prevalence, underlying mechanisms, and clinical implications of fQRS remain unknown. Methods: In this prospective study, the routine 12-lead resting ECGs of 1500 consecutive healthy adults (707 male, age [38 ± 12] years) were independently screened for fQRS by two ECG readers. fQRS was defined as ≥1 additional deflection or notching within the QRS complex, including the peak of the R-wave or the nadir of S-wave, in at least two continuous leads. Results: fQRS was identified in 76 participants (5.1%) in a mean of (2.3 ± 0.7) leads, most commonly inferior leads (86.8%, 66/76), followed by precordial leads (13.2%, 10/76). Longer QRS duration and left deviation of the frontal QRS axis of ≤30° were identified as independent predictors of fQRS. In addition, fQRS in the precordial leads covered the QRS transition lead (from R/S <1 to R/S >1) in all ten participants. Sixteen healthy volunteers who were found to have fQRS underwent late gadolinium enhancement–cardiac magnetic resonance scanning, which revealed no myocardial fibrosis, scar, or other abnormalities. Conclusions: fQRS is not rare in healthy adults. The underlying mechanisms of fQRS in healthy adults seem to be mainly related to left axis deviation (especially deviations ≤30°), rather than myocardial scar or fibrosis.

Purpose: This study aimed to investigate the intermediate- and short-term effects of transcatheter secundum atrial septal defect (ASD) closure on cardiac electric remodeling in children and adults. Methods: Fifty patients with secundum ASD referred for possible transcatheter device closure were subjected to history taking, proper physical examination, electrocardiographic assessment, and transthoracic echocardiographic examination and were evaluated before the ASD closure, 1 day, 3 months, and 6 months after closure. Results: During the 6-month follow-up, electrocardiographic parameters of remodeling were improved. P dispersion decreased from 49.73 ± 9.01 ms to 30.53 ± 5.08 ms (P = 0.004), QT dispersion decreased from 67.60 ± 5.31 to 51.13 ± 5.73 ms (P = 0.003), QRS duration decreased from 134.40 ± 4.97 ms to 116.20 ± 3.47 ms (P = 0.002), and PR interval decreased from 188.87 ± 6.06 ms to 168.00 ± 6.16 ms (P = 0.002). Electric remodeling was associated with remodeling of the cardiac chambers. At the end of follow-up, the right ventricular (RV) end-diastolic dimension decreased from 25.67 ± 5.50 mm to 17.80 ± 2.70 mm (P = 0.001) the left ventricular end-diastolic dimension increased from 33.17 ± 6.44 mm to 37.53 ± 5.15 mm (P = 0.002), mean pulmonary artery pressure decreased from 16.97 ± 3.37 mmHg to 9.22 ± 1.37 mmHg (P = 0.000), and RV systolic pressure decreased from 30.77 ± 4.69 mmHg to 18.8 ± 2.11 mmHg. After 6 months, 93.3% of the patients had normal RV size. Conclusion: Transcatheter ASD device closure leads to a significant improvement in the right-sided chambers' dimension and function and can reverse electrical changes in atrial and ventricular myocardium in children and adults after correcting hemodynamic status in short- and intermediate-term follow-up.

Implantable cardioverter-defibrillator lead failures are uncommon and predicting impending failure is challenging. We described a clinical case of a successful defibrillation despite initial detection of low high voltage impedance using Dynamic Tx algorithm, by withholding therapy if there is a short circuit and changing its shocking vector to an alternate one.