Comparing Body Mass Index and Body Surface Area for Indexing Echocardiographic Parameters: A Small Pilot Study

Dear Editor, We most commonly use echocardiography to measure cardiac dimensions and cardiac functions. There are normal dimensions as specified by the European Association of Cardiovascular Imaging and the American Society of Echocardiography in 2015.[1] According to these guidelines, all echocardiographic measurements are to be indexed by body surface area (BSA), as it had shown to be the best predictor in the multivariate analysis. However, few small studies[2-4] have used body mass index (BMI) for analyzing its effect on cardiac dimensions, but nothing conclusive could be obtained. In fact, one study has shown that in both obese and nonobese people, BSA indexing works well.[5] However, we do not have any data that compared how good BMI and BSA could index the echocardiographic parameters. Hence, we did a small retrospective analysis, where we correlated echocardiographic dimensions of normal individual without any comorbidity with both BMI and BSA and tried to find out how they correlated with these dimensions in Indian population. This was a single hospital-based retrospective study where subjects aged 35–45 years who came for routine health checkup in 1 month (March 2023) to Neotia Getwel Multispecialty Hospital, and all investigations were normal including normal lipid profile (fasting low-density lipoprotein <100 mg/dl) and euglycemia. Informed consent was obtained from all subjects. We followed the ethical standards of human experimentation (institutional and national) and we were in accordance with the Helsinki Declaration of 1964. The study was approved by the institutional review board. Transthoracic echocardiographic studies were done using Vivid S60 machines with an M3S matrix array probe with a frequency range from 1.7 to 3.2 MHz (GE Vingmed, Horten, Norway) by a single experienced cardiologist. All echocardiographic measurements were done as per standard guidelines.[1] BMI was calculated as per the standard calculation. Mosteller formula was used to calculate BSA.[6] We analyzed the echocardiographic parameters and did Pearson’s correlation between BMI and BSA with the echocardiographic parameters. A total of 42 subjects were included in the study. 22 (52.4%) were male and 20 (47.6%) were female. The mean age was 39.83 ± 3.32 years. The mean BMI was 19.96 ± 2.80 kg/m2 and the mean BSA was 1.61 ± 0.15 m2. Table 1 presents the absolute echocardiographic chamber dimensions in the study population. We did Pearson’s correlation between BMI and BSA with the echocardiographic parameters [Table 2]. We found a strong positive correlation between both BMI and BSA with left ventricular end diastolic volume (LVEdV), left ventricular end systolic volume (LVEsV), left ventricular end diastolic diameter (LVEdD), Left Atrial Volume (LAv), Left Atrial Diameter, Right ventricular end diastolic diameter (RVEdD) and a negative correlation between both BMI, BSA with Left ventricular ejection fraction and left ventricular fractional shortening. No correlation was found between either BMI or BSA with aortic dimension. The Fisher’s Z transformation of Pearson’s correlation coefficient was higher for BMI as compared to BSA for LVEdV, LVEsV, LAv, and RVEdD.Table 1: Mean values of echocardiographic parametersTable 2: Correlation between echocardiographic parameters with body mass index and body surface areaOver the years, echocardiographic parameters have been indexed by BSA. We have shown that at least in this small population, BMI was as good as BSA in indexing echocardiographic parameters. However, the sample size was very small. Hence, we need a larger multicentric study to finally substantiate the hypothesis. Authors’ contributions Avishek Bagchi: Concept, design, definition of intellectual content, literature search, clinical studies, experimental studies, data acquisition, data analysis, statistical analysis, manuscript preparation, manuscript editing and manuscript review. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.