BackgroundAtrial fibrillation (AF) is associated with myocardial infarction, and patients with AF and no obstructive coronary artery disease can present with symptoms and evidence of cardiac ischemia. We hypothesized that microvascular coronary dysfunction underlies these observations.Methods and ResultsMyocardial blood flow (MBF) at baseline and during adenosine stress and left ventricular and left atrial function were evaluated by magnetic resonance in 49 patients with AF (25 paroxysmal, 24 persistent) with no history of epicardial coronary artery disease or diabetes mellitus, before and 6 to 9 months after ablation. Findings were compared with those obtained in matched controls in sinus rhythm (n=25). Before ablation, patients with AF had impaired left atrial function and left ventricular ejection fraction and strain indices (all P<0.05 versus controls). MBF was impaired in patients both under baseline conditions (1.21±0.24 mL/min per g·[mm Hg·bpm/104]−1 versus 1.34±0.28 mL/min per g·[mm Hg·bpm/104]−1 in controls, P=0.044) and during adenosine stress (2.29±0.48 mL/min per g versus 2.73±0.37 mL/min per g in controls, P<0.001). Under baseline conditions, MBF correlated with left ventricular strain and left atrial function (all P≤0.001), so that cardiac function was most impaired in patients with the lowest MBF. Baseline and stress MBF remained unchanged postablation (both P=ns), and baseline MBF showed similar correlations with functional indices to those present preablation (all P≤0.001).ConclusionsBaseline and stress MBF are significantly impaired in patients with AF but no epicardial coronary artery disease. Reduction in MBF is proportional to severity of left ventricular and left atrial dysfunction, even after successful ablation. Coronary microvascular dysfunction may be a relevant pathophysiological mechanism in patients with a history of AF.
Introduction
Permanent His bundle pacing (PHBP) preserves physiological ventricular activation but technical difficulties have limited its widespread use. We report the first experience of PHBP performed with a new specific delivery sheath (Selectra 3D, Biotronik, Berlin, Germany) and an extendable‐retractable active screw, stylet‐driven pacing lead (Solia S 60, Biotronik).
Methods and Results
Clinical, procedural, ECG, and electrical data from consecutive patients undergoing PHBP with this system were collected at implantation, and follow‐up was performed after 1 month. Our cohort included 17 patients (71% males; mean age 76 ± 8 years) undergoing permanent pacing for sick sinus syndrome (59%) or atrioventricular block (41%). PHBP was successful in 15 (88%) procedures with mean procedure and fluoroscopy times of 63 ± 14 and 13 ± 5 min, respectively. The pacing threshold was 2.1 ± 1.1 V @1 ms and the sensed R‐wave amplitude was 5.6 ± 3.5 mV; bipolar and unipolar pacing impedances were 526 ± 115 and 369 ± 109 Ω, respectively. At discharge, neither procedure‐related complications nor lead dislodgement or pacing capture failures was reported. After 1 month, 14 (93%) patients still demonstrated His bundle stimulation and one (7%) lost His bundle capture but the lead revision was not necessary because the myocardial pacing threshold was stable. Follow‐up threshold (2 ± 1.1 vs. 2.3 ± 1.2 V@1 ms, p = .239) and sensed R‐wave amplitude (5.6 ± 3.4 vs. 6.4 ± 2.5, p = .403) was unchanged compared to the acute phase.
Conclusion
PHBP performed with a standard active fixation pacing lead and a new delivery sheath for His pacing is feasible, safe and demonstrates clinically acceptable electric performance both at implantation and after 1 month.
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