Strain can hide some states.

To the Editor,

We read the article entitled as “Speckle-tracking strain assessment of left ventricular dysfunction in synthetic cannabinoid and heroin users” with great interest (1). We congratulate the authors for performing such a trial regarding addictive substance and strain echocardiography and have some minor comments regarding the trial methodology. Authors have stated that “the trial was prospective and double-blind…”. We suggest that the authors may use “observational case-control study” and “unawareness” instead of “prospective” and “double-blind”. As we know, the main problem in observational studies is the presence of confounders and selection bias, which are prevented in randomized controlled trials through randomization and blinding. In addition, the authors concluded that SCBs are potential cause of subclinical LV dysfunction; however, reducing the levels of some LV strain parameters within the normal range might not indicate subclinical LV dysfunction, and the clinical significance of a small amount of decrease in the LV strain is unclear. We may not exclude the chance factor for statistical significance (p value) because of low sample size and low control number.