A Population-Based Study of Adherence to Guideline Recommendations and Appropriate-Use Criteria for Implantable Cardioverter Defibrillators.

Studies evaluating physician adherence to guideline recommendations for implantable cardioverter defibrillator (ICD) therapy are sparse, and none exist for the application of appropriate-use criteria (AUC) in clinical practice. As part of a quality improvement initiative, a review of all ICD procedures was performed from January 1, 2015 to December 31, 2016 in Alberta, Canada, to evaluate the proportion of patients receiving appropriate ICD therapy and to identify reasons for nonadherence. Our device-implant process involves an electrophysiologist or implanting cardiologist evaluation, reminders of ICD eligibility criteria on the device requisition, and peer-review consensus. Implants were classified according to the 2008 American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) ICD guidelines, 2013 Canadian Cardiovascular Society (CCS) Cardiac Resynchronization Therapy (CRT) guidelines, and 2013 AUC. There were 1,300 ICD procedures performed, and the mean age was 63.8 ± 12.9 years; 79% were male; the mean ejection fraction was 0.32 ± 0.13, and 69% were for primary prevention. Among all implants, < 1% were discordant with American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) recommendations. Among CRT implants, 10% were inconsistent with Canadian Cardiovascular Society (CCS) recommendations. According to AUC, 92% of implants were appropriate. Reasons for nonadherence to ACC/AHA/HRS recommendations included QRS width < 120 msec (n = 3), LVEF > 0.35 (n = 2) and recent myocardial infarction (MI) (n = 1). The most common reason for nonadherence to AUC was the absence of criteria for classification (n = 57, 4%). In this population-based study, we found that a process of specialist evaluation, eligibility reminders on device forms, and peer-review consensus may improve adherence to guideline recommendations and AUC for ICD therapy.

MELAS syndrome and cardiomyopathy: linking mitochondrial function to heart failure pathogenesis.

Heart failure remains an important clinical burden, and mitochondrial dysfunction plays a key role in its pathogenesis. The heart has a high metabolic demand, and mitochondrial function is a key determinant of myocardial performance. In mitochondrial disorders, hypertrophic remodeling is the early pattern of cardiomyopathy with progression to dilated cardiomyopathy, conduction defects and ventricular pre-excitation occurring in a significant proportion of patients. Cardiac dysfunction occurs in approximately a third of patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, a stereotypical example of a mitochondrial disorder leading to a cardiomyopathy. We performed unique comparative ultrastructural and gene expression in a MELAS heart compared with non-failing controls. Our results showed a remarkable increase in mitochondrial inclusions and increased abnormal mitochondria in MELAS cardiomyopathy coupled with variable sarcomere thickening, heterogeneous distribution of affected cardiomyocytes and a greater elevation in the expression of disease markers. Investigation and management of patients with mitochondrial cardiomyopathy should follow the well-described contemporary heart failure clinical practice guidelines and include an important role of medical and device therapies. Directed metabolic therapy is lacking, but current research strategies are dedicated toward improving mitochondrial function in patients with mitochondrial disorders.

Determinants of ventricular arrhythmias in human explanted hearts with dilated cardiomyopathy.

BACKGROUND: The molecular and cellular determinants of ventricular tachycardia (VT) in patients with nonischaemic dilated cardiomyopathy (NIDCM) remain poorly defined. MATERIALS AND METHODS: We examined 20 NIDCM hearts where VT was reported in 10 cases and VT was absent in 10 cases, using a double-blinded case-control study design, and assessed the molecular and cellular features of the adverse myocardial remodelling. RESULTS: Explanted hearts from patients with VT showed greater hypertrophic changes based on cardiomyocyte cross-sectional area and expression of disease markers, and increased myocardial fibrosis which extended into the left ventricular and right ventricular outflow tract regions. The VT group also showed increased oxidative stress with reduction in reduced glutathione levels. Connexin 43 levels in the intercalated discs showed increased levels in the VT group with reduced phosphorylation. Microarray mRNA analysis of gene expression in the left ventricle (LV) free wall revealed several families of genes which were differentially upregulated or downregulated in hearts with documented VT compared to hearts without VT. Notably, we identified reduced expression of the Ca(2+) -activated K(+) channel (KCNN2) and increased expression of the transient receptor potential cation channel 7 (TRPM7) and intracellular chloride channel 3. Western blot analysis on LV membrane fractions showed reduced KCNN2 and increased TRPM7 levels in hearts with VT. CONCLUSIONS: In explanted human hearts with NIDCM, VT is associated with greater hypertrophy, oxidative stress and myocardial fibrosis, differential gene expression, and altered ion channel levels indicative of a distinctive adverse myocardial remodelling process associated with clinically significant VT.

Predictive value of various Doppler-derived parameters of atrial conduction time for successful atrial fibrillation ablation.

Various Doppler-derived parameters of left atrial electrical remodeling have been demonstrated to predict recurrence of atrial fibrillation (AF) after AF ablation. The aim of this study was to compare three Doppler-derived measures of atrial conduction time in patients undergoing AF ablation, and to investigate their predictive value for successful procedure. In 32 prospectively enrolled patients undergoing the first AF ablation, atrial conduction time was estimated by measuring the time delay between the onset of P-wave on the surface ECG to the peak of the a'-wave on the pulsed-wave Doppler and color-coded tissue Doppler imaging of the left atrial lateral wall, and to the peak of the A-wave on the pulsed-wave Doppler of the mitral inflow. There was a significant difference in the baseline atrial conduction time measured by different echocardiographic techniques. Most (88%) patients had normal or only mildly dilated left atrium. At 6 months, 12 patients (38%) had recurrent AF/atrial tachycardia. The duration of history of AF was the only predictor of AF/atrial tachycardia recurrence following the first AF ablation (P=0.024; OR 1.023, CI 1.003-1.044). A combination of normal left atrial volume and history of paroxysmal AF of ≤48 months was associated with the best outcome. Predictive value of the Doppler derived parameters of atrial conduction time may be reduced in the early stages of left atrial remodeling. Future studies may determine which echocardiographic parameter correlates best with the extent of left atrial remodeling and is most predictive of successful AF ablation.

Ablación por radiofrecuencia de fibrilación auricular paroxística y persistente / Radiofrequency ablation of paroxysmal and persistent atrial fibrillation

La ablación por radiofrecuencia (ARF) es aceptada en la actualidad como tratamiento de la fibrilación auricular (FA) paroxística y persistente. El objetivo del presente trabajo es comparar los resultados de la ablación por radiofrecuencia con diferentes técnicas...

Radiofrequency catheter ablation (RFA) is one of the currently accepted treatments for paroxysmal and persistent atrial fibrillation (AF). Different approaches are currently used. To analyze the results of RFA in patients (pts.) with paroxysmal and persistent AF performing different techniques...

Cardiodefibrilador automático implantable: incidencia, causas y predictors de mortalidad. Valor de los registros prospectivos / Implantable automatic cardiodefibrillator: incidence causes and predictors of mortality. Value of the prospective records

The implantable automatic cardiodefibrilator (IACD) has proved to be an effective tool in the prevention of both primary and secondary sudden death. Even so, the mortality of patients receiving an IACD still remains elevated. Recent data, obtained from the secondary analysis of different studies, suggest that the discharges of the deice, between other clinical variables, both electrocardiiographic and ultrasonographic could be associated to a higher mortality, maybe due to a contribution to the progression of the cardiac insufficiency. The aims of this report were to evaluate the incidence of mortality, causes of death and the time since the implantation till the death, to analyze appropriate an inappropriate shocks and other variaables as potential predictors of mortality in patients with IACD. The results obtained in this study are detailed in the article