DISCUSSION

We assessed the role of LA global longitudinal strain by evaluating the LA remodeling in a Cameroonian T2DM adults. We included a group of diabetic patients, predominantly females, with more than half of them having coexistent hypertension. Given that global cardiovascular risk is very high in diabetic patients, its reduction constitutes a major treatment objective 12. Despite the high proportion of hypertensive patients in the population, we found only à third of them with a renin-angiotensin-aldosterone system blocker in their treatment regimen. Thus, reflecting the difficulties in applying ESC/ESH treatment recommendations 13 in Africa, especially in Cameroon, which could be linked to the relative high cost of these medications in our context, making them less available to the majority of hypertensive patients. Mean LVEF was 63.1%, corresponding to the classical presentation of patients with cardiac disease related to diabetes, where diastolic dysfunction is the main abnormality at the early stage14.
LA structural remodelling is classically expressed by the measurement of the LAVi by 2D (or 3D) echocardiography 1. Increased LAVi is a surrogate marker of increased and chronic pressure overload and is a key measurement used in clinical practice to assess diastolic dysfunction of the LV 15. The mean value of LAVi (22 ± 6 ml/m²) in the study was within the normal reference range of the American society of Echocardiography 16. However, we observed greater alterations of the reservoir function (LA global ejection fraction) and the contractile function.
PALS was significantly reduced in the study population compared to a non-diabetic black African population in South Africa (29.2 ± 9 vs 39 ± 8.3, p < 0,001)11. Meanwhile this results is similar to those found by Markman and al. in a diabetic population with a mean PALS of 28.5 ± 11.7% 17. Concerning the role of PALS in early detection diastolic and LA dysfunction, it is important to highlight that LA strain was markedly reduced in many patients with normal LAVi. In 2016, Bassam and al, had similar results in a group of hypertensive subjects in whom LA strain measured by speckle tracking echocardiography allowed early detection of LA dysfunction even before LA dilatation 7.
Finally, univariate linear regression allowed to highlight a significative negative association of PALS with age, BMI, SBP, E/E’ ratio and LAVi. The reservoir (LA expansion index and LA global ejection fraction) and the contractile functions were positively correlated to PALS. Cardiac disease during diabetes leads to atrial fibrosis with consequent reduced atrial compliance 18. Muranaka and al, also suggested that LA fibrotic modifications during T2DM are responsible for reduced phasic functions determined by LA strain19.
This study had several limitations: (i) LA strain measurement lacks a criterion standard - strain values vary with different software packages; (ii) the quantitative values defined for LA strain are vendor-specific; (iii) the software used for assessing strain does not have a specific mode for LA strain study; and (iv) coronarography which is the gold standard to exclude coronary artery disease could not be performed.