In this study, we investigated the value of LAKE, an indicator of left atrial mechanical function, in predicting AF recurrence 1 month later in patients with persistent AF who underwent SR by applying electrical direct current cardioversion. LAKE was found to be significantly lower in the AF group than in the SR group, and LAKE, LA diameter and AF duration were found to be independent predictors of AF recurrence at 1 month.
LAKE is an important indicator of the contribution of the left atrium in left ventricular filling. In patients with abnormal diastolic dysfunctions, such as hypertrophic cardiomyopathy, ventricular filling is impaired. As a compensatory mechanism to overcome this situation, left atrial contractility may increase as a result of the Frank-Starling mechanism, which provides adequate left ventricular filling (11). Similarly, in patients with mitral stenosis, there is a compensatory increase in LA mechanical function against the stenotic valve before left atrial insufficiency develops (12). However, when mitral stenosis progresses and becomes symptomatic, LAKE gradually decreases instead of increasing due to persistent loading in the left atrium (13). Again, in patients with heart failure—especially in patients with mild to moderate heart failure symptoms—an increase in LA mechanical function occurs to compensate for the decreased left ventricular function (14). However, as heart failure progresses, left atrial function also deteriorates, and LAKE decreases (13, 15). In a study performed by Chrysohoou et al., 6-month follow-ups revealed a higher frequency of cardiovascular events in patients with newly diagnosed left ventricular failure and impaired LA mechanical function (16).
In a study comparing 2 groups consisting of paroxysmal AF patients and normal individuals, no significant difference was found between the 2 groups in terms of LAKE (17). One of the issues discussed in the study was the exclusion of persistent/permanent AF patients. This is an issue because deterioration in LA mechanical function is expected to be more common in the chronic stage.
As discussed above, LA is an attempt to compensate for the stroke volume by increasing its mechanical function as a result of Frank-Starling mechanisms in order to overcome the problems in the left ventricle or valve (11, 12). However, after a while, especially as the diseases progress, the LA structure begins to deteriorate, and mechanical function decreases (13). Deteriorated SoA is more prone to the development of atrial fibrillation. LAKE, which is an important indicator of LA mechanical function, also decreases over time. In our study, LAKE was found to be lower in patients with AF recurrence at 1-month follow-up after cardioversion.
LA diameter is one of the parameters that predicts AF recurrence at 1 month in multivariate analysis. Decreased atrial function and AF recurrence are expected to occur in patients with an enlarged LA diameter, and this has also been shown in previous studies (3, 4). The antero-posterior diameter of the LA was measured in our patients, but the 3-dimensional anatomy of the LA may provide more valuable information. The fact that LAKE is a predictor of AF recurrence independent of LA diameter is an indicator that LA function cannot be evaluated with LA diameter alone.
AF duration is another independent predictor of AF recurrence. As the duration of AF increases, LV mechanical function gradually worsens, atrial fibrosis increases, and AF recurrence increases in patients undergoing cardioversion. Especially in patients with an AF duration of 3 months or more, atrial functions begin to decrease, and AF recurrence increases (18). In our study, the AF duration was found to be longer in the group with AF recurrence. In addition, the high rate of AF recurrence (32.5%) seen at 1 month can be explained by the long AF durations in our study group. The duration of AF was 4.74 months in the SR group and 6.92 months in the AF group.
It has been shown that LAKE is reduced in patients with AF recurrence. Due to the success of LAKE in showing 1-month short-term recurrences, AF recurrence may be prevented by applying more aggressive treatment in patients with low LAKE values.
The relatively small number of patients is the first limitation of our study. Due to this limited number of patients, the study may not be representative of the entire population. In addition, the follow-up period is as short as 1 month. It should be investigated whether the 1-month follow-up results are an indicator for the success of LAKE in predicting AF recurrence in long-term follow-ups.