"First-degree AV block-a benign entity?" Insertable cardiac monitor in patients with 1st-degree AV block reveals presence or progression to higher grade block or bradycardia requiring pacemaker implant.

BACKGROUND: First-degree AV block has in the past generally been considered a benign condition. A few recent studies have shown that 1st-degree AV block is associated with an increased risk for heart failure, pacemaker (IPG) implantation, and death. We investigated the outcomes of patients who received an insertable cardiac monitor (ICM) (Medtronic Reveal XT®) within the scope of the INSIGHT XT study and had 1st-degree AV block at baseline. METHODS: The observational, international, multi-center INSIGHT (R)XT study prospectively enrolled 1003 patients implanted with an ICM for arrhythmia diagnosis, irrespective of the clinical indication. This analysis includes 37 patients who had documented 1st-degree AV block at enrolment. Patients with known concurrent higher grade block at enrolment were excluded. RESULTS: The indications for rhythm monitoring and ICM implantation were syncope/pre-syncope in 54.1%, cryptogenic stroke in 18.9%, AF with rhythm control intervention in 21.6%, and unexplained palpitations in 5.4%. Mean age was 68 ± 14 years, 75.7% were male, and concurrent bundle branch block was present in 8.1%. The median follow-up time was 12.2 months (IQR3.9-15.9). Fifteen patients (40.5%) received an IPG during the follow-up, and in 93.3% of the cases, the implant was needed to treat a now detected more severe bradycardia or progression of the conduction disease. CONCLUSIONS: ICM either revealed progression of 1st-degree AV block to a higher grade block (53%) or detected an already existing more severe bradycardia warranting an IPG in 40.5% patients. This finding supports the conclusion that 1st-degree AV block might be a risk marker for more severe intermittent conduction disease and is not benign in all patients. Further studies may reveal patient subgroups which are at risk for demonstrating or developing higher grade AV block and may warrant a future IPG implantation.

Costs of unstructured investigation of unexplained syncope: insights from a micro-costing analysis of the observational PICTURE registry.

AIMS: The observational PICTURE (Place of Reveal In the Care pathway and Treatment of patients with Unexplained Recurrent Syncope) registry enrolled 570 patients with unexplained syncope, documented their care pathway and the various tests they underwent before the insertion of an implantable loop recorder (ILR). The aims were to describe the extent and cost of diagnostic tests performed before the implant. METHODS AND RESULTS: Actual costs of 17 predefined diagnostic tests were characterized based on a combination of data from PICTURE and a micro-costing study performed at a medium-sized UK university hospital in the UK. The median cost of diagnostic tests per patient was £1114 (95% CI £995-£1233). As many patients received more than the median number of tests, the mean expenditure per patient was higher with £1613 (95% CI £1494-£1732), and for 10% of the patients the cost exceeded £3539. Tests were frequently repeated, and early use of specific and expensive tests was common. In the 12% of patients with types of tests entirely within the recommendations for an initial evaluation before ILR implant, the mean cost was £710. CONCLUSION: Important opportunities to reduce test-related costs before an ILR implant were identified, e.g. by more appropriate use of tests recommended in the initial evaluation, by decreasing repetition of tests, and by avoiding early use of specialized and expensive tests. A structured multidisciplinary approach would be the best model to achieve an optimal outcome.

Unexplained syncope: implications of age and gender on patient characteristics and evaluation, the diagnostic yield of an implantable loop recorder, and the subsequent treatment.

BACKGROUND: Syncope is a common clinical problem with a variety of underlying mechanisms, some of which occur more frequently in 1 of the sexes or at a certain age. HYPOTHESIS: There may be clinically significant age- and gender-related differences in patients with unexplained syncope. METHODS: Five hundred seventy patients (54% women) with unexplained syncope received an implantable loop recorder (ILR) and were followed until diagnosis or for at least 1 year. RESULTS: Women were older and more prone to severe trauma during syncope (40.8% vs 29.9%, P = 0.007), and hospitalization was more common at ≥65 years (P = 0.003) without gender difference. Muscle spasms or grand mal seizures were more common in men and at <65 years old. Carotid sinus pressure, exercise testing, coronary angiography and magnetic resonance imaging/computed tomography scans were more commonly performed in men, whereas no test was more common in women. Tilt testing, exercise test, electroencephalography, and neurological or psychiatric evaluation were more common at ≥65 years. There were no age- or gender-related differences in the diagnostic yield of the ILR, whereas patients ≥65 years old more often received specific treatment based on ILR data. CONCLUSIONS: Gender and/or age had relevance for the clinical evaluation, rate of recurrence, and subsequent specific treatment but not for the diagnostic yield of the ILR.

Early versus delayed implantation of a loop recorder in patients with unexplained syncope--effects on care pathway and diagnostic yield.

BACKGROUND: This study looked to assess the care pathway and diagnostic yield in patients who received an implantable loop recorder (ILR) after an "initial phase of the diagnostic work-up" (initial work-up) or after a "full evaluation" of unexplained syncope. METHODS AND RESULTS: Physicians classified the timing of an ILR implant in 514 patients as either following an "initial work-up" (n=128; 25%) or "full evaluation" (n=386; 75%). Patients with an "initial work-up" underwent a median (IQ range) of 8 (6-14) tests prior to ILR implant compared to 14 (10-21) tests after "full evaluation" (p<0.0001). Hospitalization and injury before implant were less common in patients with an "initial work-up": 53 vs. 75%, p<0001, and 23% vs. 39%, p<0.001, as were visits to specialists, e.g. neurologist, 32% vs. 50%, p<0.001. At one year after implant, the syncope recurrence rate was 32% in the initial work-up group and 36% in the full evaluation group, and the incidence of recurrences with an ILR-guided diagnosis was 52% and 75% respectively. Diagnoses were cardiac in 90% after "initial work-up" vs. 79% after "full evaluation". CONCLUSIONS: Patients who only underwent an "initial work-up" had fewer investigations and a lower incidence of injury or hospitalization. The diagnostic yield from the ILR was high in both groups. Patients in both groups underwent more investigations than suggested in the ESC guidelines and could have benefitted from limiting the initial evaluation before an ILR is implanted.

Performance of a new leadless implantable cardiac monitor in detecting and quantifying atrial fibrillation: Results of the XPECT trial.

BACKGROUND: Current methods for detecting atrial fibrillation (AF) have limited diagnostic yield. Continuous monitoring with automatic arrhythmia detection and classification may improve detection of symptomatic and asymptomatic AF and subsequent patient treatment. The study purpose was to quantify the performance of the first implantable leadless cardiac monitor (ICM) with dedicated AF detection capabilities. METHODS AND RESULTS: Patients (n=247) with an implanted ICM (Reveal XT, Medtronic Inc, Minneapolis, Minn) who were likely to present with paroxysmal AF were selected. A special Holter device stored 46 hours of subcutaneously recorded ECG, ICM markers, and 2 surface ECG leads. The ICM automatic arrhythmia classification was compared with the core laboratory classification of the surface ECG. Of the 206 analyzable Holter recordings collected, 76 (37%) contained at least 1 episode of core laboratory classified AF. The sensitivity, specificity, positive predictive value, and negative predictive value for identifying patients with any AF were 96.1%, 85.4%, 79.3%, and 97.4%, respectively. The AF burden measured with the ICM was very well correlated with the reference value derived from the Holter (Pearson coefficient=0.97). The overall accuracy of the ICM for detecting AF was 98.5%. CONCLUSIONS: In this ICM validation study, the dedicated AF detection algorithm reliably detected the presence or absence of AF and the AF burden was accurately quantified. The ICM is a promising new diagnostic and monitoring tool for the clinician to treat AF patients independently of symptoms. Long-term studies are needed to evaluate the clinical benefits of the technology.