Strain Rate Imaging for Noninvasive Functional Quantification of the Left Atrium in Hypertensive Patients with Paroxysmal Atrial Fibrillation

Abstract

Aim: Strain rate (SR) imaging has been applied to the detection of regional left ventricular (LV) dysfunction but not as much to the assessment of left atrial (LA) function. We aimed to assess atrial myocardial properties during atrial fibrillation (AF) by myocardial velocity, SR and strain, focusing on the effects of hypertension and atrial arrhythmias, especially paroxysmal AF. Methods: We compared 3 groups of a total of 110 consecutive patients with hypertension presenting to our institution: 20 with brief atrial tachycardia, 20 with paroxysmal AF and 70 with hypertension alone. These patients and 32 controls underwent transthoracic echocardiography, tissue velocity imaging (TVI), strain examination and SR imaging. Atrial tissue velocity, strain and SR values of hypertensive patients were compared with those of age-matched controls. Results: Compared with controls, hypertensive patients with paroxysmal AF showed significantly increased atrial myocardial features as assessed by TVI (p < 0.05–0.001). Time to peak late diastolic SR corrected for heart rate (TASRc) and the difference of early diastolic SR (ΔESR) were significantly increased (both p < 0.05), whereas the difference of late diastolic SR (ΔASR) (p < 0.05) and the difference of TASRc (ΔTASRc) (p < 0.001) were significantly decreased; moreover, systolic SR (SSR), ΔASR and ΔTASRc were significantly decreased (p < 0.05, p < 0.01 and p < 0.001, respectively), whereas ΔESR was significantly increased (p < 0.01), as compared with hypertensive patients without arrhythmia. No other parameters differed among the 4 groups. Conclusions: SR imaging combined with TVI enables noninvasive quantification of LA dysfunction due to hypertension and paroxysmal AF. In hypertensive patients, paroxysmal AF decreases the efficiency, not the ability, of LA myocardia to reserve potential energy, which suggests that LA myocardial reservoir function decreases. The impaired conductivity of the left atrium leads to decreased total active atrial contraction and prolonged interatrial conduction. Thus, the temporal asynchrony of the atria is enhanced, but contraction asynchrony is reduced.