Electromechanical dissociation of left atrium in patients with Cardiac Amyloidosis by Magnetic Resonance: Prognostic and clinical correlates

Abstract

Objectives Left atrial (LA) function is an important marker of hemodynamic status in cardiac amyloidosis (CA), and its characterization may provide relevant prognostic information. We sought to assess the prevalence and prognostic impact of LA dysfunction by cardiac magnetic resonance (CMR) in patients with CA. Methods We performed CMR in 80 consecutive patients with CA, including 38 with AL (47%) and 42 with ATTR (53%). LA function was assessed by acquiring short axis cine steady-state free precession (SSFP) covering the entire chamber. The atrial emptying fraction (AEF) was calculated as the ratio between the difference of LA maximal and minimal volume to LA maximal volume, expressed as percentage. Severe atrial dysfunction was defined as AEF ≤ 14%. Results Mean AEF was 18% (13–35%). Overall, AEF ≤ 14% was present in 19 patients (24%), including 21% of those in sinus rhythm (SR) with no history of atrial fibrillation (AF). After a median of 3 years (IQR 2–4), 36 patients (44%) died of cardiac causes. Patients with AEF ≤ 14% showed increased cardiac mortality, with an independent OR of 4.2 (95 IC 2.1–8.2, P < 0.0001). Of note, AEF ≤ 14% was the stronger independent predictor of cardiac death. Patients in SR with AEF ≤ 14% had worse outcome than those with AF. Conclusions Severe impairment of LA contractile function was present in three-quarters of patients with CA, and was prevalent irrespective of CA etiology, both in the presence and absence of AF. Severe LA dysfunction was associated with an independent 4-fold increase in risk for cardiac death at three years.

Echocardiographic Assessment of Atrial Function: From Basic Mechanics to Specific Cardiac Diseases

“…However, LA size is insufficient to obtain detailed information about LA function. Several studies with STE demonstrated that LA systolic contraction, reservoir and conduit functions were impaired in cardiac amyloidosis [ 69 , 70 ]. Recently, Bandera and colleagues [ 20 ] reported substantial impairment of the three phasic functional atrial components (median reservoir strain 8.9%, conduit strain 6.5%, pump strain 4.0%) evaluated by STE.…”

Clinical Importance of Left Atrial Infiltration in Cardiac Transthyretin Amyloidosis

“…Echo-speckle tracking now has an established role in the characterization of atrial function ( 13 ) and can assess the ability of the atria to expand during ventricular systole (reservoir function), the early-diastolic emptying (conduit function), the atrial shortening (atrial contraction), and—when associated with the estimation of LV pressures—the resistance to deformation of the LA (LA stiffness) ( 14 ). Preliminary findings in cardiac amyloidosis have demonstrated impaired atrial systolic contraction ( 15 ) but also loss of reservoir function, resulting in an atrium that acts merely as a conduit throughout the cardiac cycle ( 16 , 17 ). To date, only small retrospective speckle-tracking studies have been conducted in ATTR amyloidosis, and along with little in the way of histological evaluation of the atrial wall, the significance of atrial infiltration, remodeling, and dysfunction in the pathophysiology of cardiac ATTR amyloidosis is not clear.…”

Arrhythmic Burden in Cardiac Amyloidosis: What We Know and What We Do Not

“…In this context, the detection of myocardial deformation by speckle tracking at echocardiography allows the identification of one-fifth of patients who show a severe impairment of contractility despite remaining in sinus rhythm on the electrocardiogram [ 20 ]. This condition is also known as atrial electromechanical dissociation, proven to be associated with a poor prognosis [ 9 , 21 ].…”