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Re: The effect of diabetes mellitus on regional myocardial function

To the Editor: We are interesting to read the excellent work by Eshoo et al.1 which investigated phasic atrial function in patients with mild hypertension by using strain and strain rate. One of their main conclusions was that mild hypertension resulted in a reduction in left atrial (LA) conduit volume although maximal LA volume was unchanged. They reported that the early diastolic strain rate (E-Sr) in the hypertension group was significantly lower than the normal cohort by an average of 14.3% (95% CI 2- 25.1%, p = 0.02).

Previous studies have investigated the effects of diabetes mellitus on regional myocardial function. Kosmala et al.2 reported that both left ventricular (LV) systolic and diastolic dysfunction can be detected in diabetic patients without systemic hypertension. Pattoneri et al.3 reported that myocardial performance index was significantly higher in diabetic patients independently of the hypertension occurrence. Muranaka et al.4 in a recent study found that the diabetic patients had impaired LA reservoir and conduit functions than normal subjects by using strain rate imaging. Though the relationship between diabetes mellitus and regional myocardial function has not been fully investigated, the current literature implies that diabetes mellitus may lead to decrease of regional myocardial function in both LV and LA.

Eshoo et al. in their study mentioned that fourteen of the fifty-four patients (about 26% of the sample size) were diagnosised as diabetes mellitus.1 Besides, the potential effect of insulin resistance, which has been reported to be associated with impaired diastolic function of the left ventricle,5 was not considered by the authors, either. Due to the potential effects of diabetes mellitus on regional myocardial function, the fourteen diabetic patients may confound the results of the whole study. The decrease of E-Sr reported in their study may due to the confounding effects of the diabetes mellitus. Thus we suggest the authors reanalyze the data by excluding the diabetic patients.

REFERENCES

1. Eshoo S, Boyd AC, Ross DL, et al. Strain rate evaluation of phasic atrial function in hypertension. Heart. 2009 Apr 26. [Epub ahead of print]

2. Kosmala W, Kucharski W, Przewlocka-Kosmala M, et al. Comparison of left ventricular function by tissue Doppler imaging in patients with diabetes mellitus without systemic hypertension versus diabetes mellitus with systemic hypertension. Am J Cardiol. 2004 Aug 1;94(3):395-9.

3. Pattoneri P, Sozzi FB, Catellani E, et al. Myocardial involvement during the early course of type 2 diabetes mellitus: usefulness of myocardial performance index. Cardiovasc Ultrasound. 2008 Jun 5;6:27.

4. Muranaka A, Yuda S, Tsuchihashi K, et al. Quantitative assessment of left ventricular and left atrial functions by strain rate imaging in diabetic patients with and without hypertension. Echocardiography. 2009 Mar;26(3):262-71. Epub 2008 Nov 11.