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Aims: The aim of the study was to verify in what proportion of patients, device-detected atrial high rate (AHR) episodes are indeed atrial arrhythmias (AAs). We investigated also the reasons for inappropriate arrhythmia classification and assessed if patients with misdiagnosed arrhythmias have distinct characteristics that would help to identify them.Methods and Results: The study population consisted of 304 consecutive patients implanted with cardiac resynchronization therapy defibrillators (CRT-Ds) and subsequently monitored via remote monitoring for a median follow-up (FU) of 30.5 months. Intracardiac electrograms of every recorded AHR episode were assessed and classified (AA vs. no AA) by two experienced cardiologists. During FU, 14 386 episodes of AHR were recorded and classified in 176 (57.9%) patients. In 89.2% of them, these episodes were true AA (94% atrial fibrillation, 62% de novo). The reasons for AHR misdiagnosis were atrial far-field signals (89.5%) and noise (10.5%). The mean per cent of day spent in AHR (54.9 vs. 5.86%; P < 0.001) and the occurrence of periods with low CRT pacing (82.8 vs. 55%; P = 0.003) were significantly higher in AA subjects than in those with misdiagnosed AHR. Episode duration of properly detected AHRs was longer than that of misdiagnosed AHRs. Higher per cent of time spent in AHR was an independent marker of appropriate arrhythmia detection [adjusted hazard ratio (HR) 1.04; P = 0.023].Conclusion: Nearly two-thirds of CRT-D patients had AHR episodes within 2.5 years after implantation. Almost 90% of AHRs were indeed AA. Misdetections were caused by far-field sensing or noise. A two-step diagnostic algorithm (>9% of time spent in AHRs and episode duration >36 s) allowed for proper detection of AA with a high hit-rate and specificity. [ABSTRACT FROM AUTHOR]

Aim To assess incidence, predisposing factors and outcomes of cardiac device-related infective endocarditis (CDRIE) in patients undergoing cardiac resynchronization therapy (CRT). Methods and results High-volume, single-center cardiology database was screened to identify all CDRIE cases, based on modified Duke criteria, amongst 765 consecutive CRT implantations between 2002 and 2015 (70.8% de novo implantations, 13.7% and 15.5% up-grades from pacemaker and implantable cardioverter–defibrillator [ICD], respectively). During the median follow-up (FU) of 1207 days (range: 256–2664) overall 38 CDRIE (4.97%) cases were identified (incidence: 15/1000 person-years). Multivariate Cox regression model, incorporating significant baseline differences as covariates (model 1), demonstrated that both up-grade from ICD to CRT and higher baseline NYHA class were independently associated with increased risk of CDRIE (adjusted HR 4.29, 95%CI 1.93–9.57; and HR 2.43, 95%CI 1.32–4.49, respectively). In the second model (including all differences with P < 0.2) up-grade from ICD (HR 4.36, 95%CI 1.96–9.69), higher NYHA class (HR 2.04, 95%CI 1.11–3.75), hypertrophic cardiomyopathy (HR 5.85, 95% CI 1.46–23.52), lower baseline hemoglobin level (HR 0.68, 95%CI 0.50–0.94) and chronic obstructive pulmonary disease (HR 2.46, 95%CI 1.05–5.77) were all independently associated with higher risk of CDRIE. All-cause mortality in patients with CDRIE was significantly higher than in subjects without infective complications (68.4% vs. 33.7%, P < 0.001), and 50% of patients with CDRIE died during index hospitalization. Conclusions The prevalence of CDRIE in CRT recipients is almost 5% within 3.5 years post implantation. Up-grade from ICD and high baseline NYHA class flag up patients at high-risk of CDRIE. CRT-related infective complications are associated with very poor prognosis. [ABSTRACT FROM AUTHOR]

Background Incidence and clinical significance of transient, daily fluctuations of biventricular pacing percentage (CRT%) remain unknown. We assessed the value of daily remote monitoring in identifying prognostically critical burden of low CRT%. Methods and results Prospective, single-centre registry encompassed 304 consecutive heart failure patients with cardiac resynchronization therapy defibrillators (CRT-D). Patients with 24-h episodes of CRT% loss < 95% were assigned to quartiles depending on cumulative time spent in low CRT%: quartile 1 (1–8 days), 2 (9–20 days), 3 (21–60 days) and quartile 4 (> 60 days). During median follow-up of 35 months 51,826 transmissions were analysed, including 15,029 in 208 (68.4%) patients with episodes of low CRT%. Overall, mean CRT% ≥ 95% vs. < 95% resulted in a 4-fold lower mortality (17.3 vs. 68.2%; p < 0.001). Fifty-four percent of patients experienced episodes of CRT% loss, despite 85.6% having mean CRT% ≥ 95%. Mortality was lowest in quartile 1 (7.7%), while longer periods of CRT% loss resulted in significantly higher death rates (25.0 vs. 34.6 vs. 57.7%; quartiles 2–4 respectively, p < 0.001), despite mean CRT% still being ≥ 95% in quartiles 1–3. Cumulative low CRT% burden was the independent risk factor for death (HR 1.013; 95% CI 1.006–1.021; p < 0.001). Mortality rose by 1.3 and 49% with every additional day and quartile of CRT% loss, respectively. Conclusions Daily remote monitoring allows one to detect 24-h episodes of CRT% loss < 95% in over two-thirds of CRT-D recipients during median observation of 3 years. Cumulative low CRT% burden (in days) independently predicts mortality before mean CRT% drop. [ABSTRACT FROM AUTHOR]