Behavior of leadless atrioventricular synchronous pacing during exercise.

Background: The leadless Micra AV pacemaker is designed to provide atrioventricular (AV) synchronous tracking by detecting atrial contraction. Detection of the mechanical atrial signals can become challenging at a fast sinus rate.

Objective: The purpose of the study was to evaluate the AV synchronous performance during exercise in outpatients implanted with a Micra AV pacemaker.

Blood pressure response to graded bicycle exercise in males and females across the age and fitness spectrum.

Aim: Blood pressure (BP) responses to exercise are frequently measured, with the concern that greater increases are a marker of disease. We sought to characterize the normal exercise BP response in healthy adults and its relationships with age, sex, and fitness.

Methods: 589 participants (median age 46 [IQR 24-56] years, 81% male) underwent cardiopulmonary exercise testing with repeated, automated BP measures.

Inter- and intra-observer variability of visual fragmented QRS scoring in ischemic and non-ischemic cardiomyopathy.

Background: Fragmented QRS (fQRS) on a 12-lead ECG has been linked with adverse outcome. However, the visual scoring of ECGs is prone to inter- and intra-observer variability.

Methods: Five observers, two experienced and three novel, assessed fQRS in 712 digital ECGs, 100 were re-evaluated to assess intra-observer variability.

Inferior and anterior QRS fragmentation have different prognostic value in patients who received an implantable defibrillator in primary prevention of sudden cardiac death.

Aims: QRS fragmentation (fQRS) has been proposed as a predictor of sudden cardiac death (SCD) and all-cause mortality in ischemic (ICM) and non-ischemic cardiomyopathy patients. However the value of fQRS in patients with a LVEF <35% is a matter of debate.

Methods: All consecutive patients with an indication for an ICD in primary prevention of SCD were included in a retrospective registry from 1996 until 2013.

T-Wave Alternans Is Linked to Microvascular Obstruction and to Recurrent Coronary Ischemia After Myocardial Infarction.

The purpose of this study is to investigate the relationship between T-wave alternans (TWA), infarct size and microvascular obstruction (MVO) and recurrent cardiac morbidity after ST elevation myocardial infarction (STEMI). One hundred six patients underwent TWA testing 1-12 months and 57 patients underwent cardiac magnetic resonance imaging (MRI) in the first 2-4 days after STEMI. During follow-up (3.