Luong, Christina

Background: Left atrial (LA) size increases in atrial fibrillation (AF). How changes in mitral annulus and atrial volume over time relate to severity of mitral regurgitation (MR) is unknown. Methods: This cohort study included 160 patients with a history of permanent AF who had at least 2 transthoracic echocardiograms (TTE) performed between 2005 and 2010 at Vancouver General Hospital (British Columbia, Canada). Patients with structural mitral valve disease, congenital heart disease, more than mild-moderate mitral/tricuspid regurgitation on their first TTE were excluded from analyses. LA volume was determined using biplane area-length method, averaged over 3 cardiac cycles. The mitral annulus diameter (MAD), defined as the distance between the hinge points of the anterior and posterior mitral leaflets from the apical 4-chamber view, was measured during end-systole and end-diastole. Linear mixed effects modeling was used in analyzing the above measurements for change over time. Mitral regurgitation was classified into 3 grades (mild, moderate, or severe) using standard color Doppler and PISA easurements where available. Results: Of the 160 subjects included in this analysis, 100 were men (62.5%). The mean age at study entry was 74±10 years. The median number of TTE performed was 3 (range 2 - 6). All 160 patients showed a progressive increase in MAD over time. There was a significant increase in MAD at end-systole and end-diastole over a mean follow-up of 3.2 ± 2.8 years; the increases were 0.48 mm/year (95% CI 0.124 -0.75, P=0.0037) and 0.45 mm/year (95% CI 0.102-0.716, P=0.0029) respectively. LA volume increased from a mean of 43 mL/m2 to 75 mL/m2 for the cohort, or 10 mL/m2 per year. Adjusting for age, sex, and left ventricular ejection fraction, an increase in MR severity by at least 1 grade was strongly and independently associated with an increase in MAD. A 15% increment in MAD was associated with an increase in MR severity by 1 grade. Conclusion: Permanent AF was associated with significant increases in MAD and LA volume over time. Severity of MR also significantly increased over time, and was independently related to the change in MAD. Further investigations as to whether this represents a mechanism for left heart failure in patients with permanent AF are warranted.

Abstract Background Noninvasive parameters of LV filling pressure (E/e’) and pulmonary pressures (RVSP) by Doppler echocardiography correlate with functional capacity and outcome in sinus rhythm (SR). Their role in AF is less clear. Elevated left ventricular filling pressures (E/e’) and pulmonary artery systolic pressures (PASP) by Doppler stress echocardiography correlate with impaired functional capacity in patients in sinus rhythm (SR). However, there is limited data in atrial fibrillation (AF). Purpose The aim of this study was to delineate the characteristics of patients with AF referred for exercise stress echocardiography and determine the prevalence and significance of E/e’ and PASP elevations in AF. Methods Subjects were patients referred for exercise treadmill stress echocardiography (n= 14,937) and underwent regional wall motion assessment, Doppler assessment of mitral inflow (E) and early tissue relaxation (e’) velocities and PASP at rest and immediately following maximum symptom limited exercise. Exclusion criteria included significant valvular heart disease (moderate or greater stenosis and/or regurgitation of any cardiac valve or previous valve repair or replacement) (1%), congenital heart disease (<1%) or refusal to participate in research (<1%). Results Patients with AF (n = 310, 2%) were older (71 ± 10 vs 59 ± 13 years, p < 0.001). While resting blood pressure was similar, resting heart rates were higher in AF (80 ± 17 bpm vs 73 ± 13 bpm, p < 0.0001). AF patients achieved lower workloads (6.4 ± 2.4 METS vs 9 ± 2.4 METS, p < 0.001) with lower peak double products (22336 ± 6677 vs 25148 ± 5438, p < 0.001). Rates of resting (27% vs 10%, p < 0.0001) and exercise-induced (37% vs 20%, p < 0.0001) regional wall motion abnormalities were higher in AF. Mean E/e’ was higher in AF at rest (12 ± 5 vs 9 ± 3, p < 0.001) and with exercise (12 ± 5 vs 10 ± 4, p < 0.001), with a higher percentage of patients in AF having E/e’ ≥15 at rest (20% vs 6% in SR, p= <0.001) and with exercise in (23% vs 8%, p < 0.001). PASP was higher in AF at rest (33 ± 8 mm Hg vs 28 ± 6 mm Hg, p < 0.001) and with exercise (48 ± 12 vs 42 ± 11, p < 0.001) compared to SR. E/e’ correlated with exercise capacity in AF and in SR, with an E/e’ cutoff of 11.7 that was best predictive of impaired functional capacity (< 5 METS in women and < 7 METS in men). Conclusions Abnormalities of E/e’ and PASP are more prevalent in patients with AF and correlate with impaired functional capacity. In patients with AF, a medial E/e’ ratio of ≥ 12 immediately following exercise is best associated with impaired functional capacity.

Focused cardiac ultrasonography is performed by clinicians at the bedside and is used in time‐sensitive scenarios to evaluate a patient's cardiovascular status when comprehensive echocardiography is not immediately available. This simplified cardiac ultrasonography is often performed by noncardiologists using small, portable devices to augment the physical examination, triage patients, and direct management in both critical care and outpatient settings. However, as the use of focused cardiac ultrasonography continues to expand, careful consideration is required regarding training, scope of practice, impact on patient outcomes, and medicolegal implications. In this review, we examine some of the challenges with rapid uptake of this technique and explore the benefits and potential risk of focused cardiac ultrasonography. We propose possible mechanisms for cross‐specialty collaboration, quality improvement, and oversight.