Is the Macruz Index a Marker of Atrial Cardiomyopathy in Stroke Patients With Sinus Rhythm

INTRODUCTION We read with great interest the study entitled “The Role of the Macruz Index in Stroke Patients: Predictive Value and Atrial Remodeling” by Arslan and Söner, published in the most recent issue of your journal.(1) The authors’ evaluation of the Macruz index as an indicator of atrial remodeling in stroke patients without a diagnosis of atrial fibrillation (AF), as well as the finding of significantly higher Macruz index values despite sinus rhythm, is particularly intriguing. This study provides a valuable contribution to the literature, especially at a time when the concepts of cryptogenic stroke and atrial cardiomyopathy are gaining increasing clinical importance. However, we would like to highlight several points in order to interpret the clinical implications of the study from a broader perspective within the framework of the contemporary concept of atrial cardiomyopathy. First, the study appears to rely solely on left atrial diameter (>45 mm) as a criterion for excluding atrial structural remodeling. In contrast, current ESC guidelines and contemporary literature recommend the use of the left atrial volume index (LAVI), rather than a one-dimensional linear diameter measurement, for the assessment of atrial remodeling.(2)Given the asymmetric nature of left atrial enlargement, atrial volume may be increased even when the linear diameter remains within normal limits. Importantly, the concept of atrial cardiomyopathy encompasses pathological processes such as fibrosis, endothelial dysfunction, and mechanical dysfunction—particularly impaired reservoir function—that may begin before overt anatomical atrial enlargement becomes evident. In this context, the elevated Macruz index observed in the study may represent an electrophysiological manifestation of early-stage atrial cardiomyopathy that precedes echocardiographically detectable atrial dilatation. Future studies correlating the Macruz index with more sensitive functional parameters, such as left atrial strain assessed by deformation imaging, may provide a stronger pathophysiological basis for the clinical significance of this index.(3) Second, electrocardiographic parameters including P-wave axis, voltage, P-wave area, and P-wave dispersion are widely accepted markers of atrial remodeling. The absence of these parameters from the analysis and the lack of evaluation of their association with the Macruz index may be considered a limitation of the study. Incorporating these ECG-derived markers in future research could offer additional insights into the electrophysiological mechanisms underlying atrial remodeling.(2) In this regard, the development of a composite or integrative index combining these parameters might also be considered. Finally, the selection of the control group from patients presenting with palpitations, along with differences in age and comorbidity profiles between the stroke and control groups, should be taken into account when interpreting the results. In addition to potential sympathetic activation, age-related atrial changes in patients with palpitations may independently influence the Macruz index, irrespective of stroke pathology.(4) We congratulate Arslan and Söner on their insightful work drawing attention to “hidden” atrial vulnerability in stroke patients without documented atrial fibrillation, and we hope that this study will stimulate further research incorporating comprehensive imaging modalities and prolonged rhythm monitoring strategies.