Effect of empagliflozin on left ventricular contractility and peak oxygen uptake in subjects with type 2 diabetes without heart disease: results of the EMPA-HEART trial

Background

The mechanism through which sodium-glucose cotransporter 2 inhibitors (SGLT2i) prevent the incidence of heart failure and/or affect cardiac structure and function remains unclear.

Methods

The EMPA-HEART trial is aimed at verifying whether empagliflozin improves myocardial contractility (left ventricle global longitudinal strain, LV-GLS) and/or cardiopulmonary fitness (peak oxygen uptake, VO2peak) in subjects with type 2 diabetes (T2D) without heart disease. Patients with T2D, normal LV systolic function (2D-Echo EF > 50%), and no heart disease were randomized to either empagliflozin 10 mg or sitagliptin 100 mg for 6 months and underwent repeated cardiopulmonary exercise tests with echocardiography and determination of plasma biomarkers.

Results

Forty-four patients completed the study, 22 per arm. Despite comparable glycaemic control, modest reductions in body weight (− 1.6; [− 2.7/− 0.5] kg, p = 0.03) and plasma uric acid (− 1.5; [− 2.3/− 0.6], p = 0.002), as well as an increase in haemoglobin (+ 0.7; [+ 0.2/+ 1.1] g/dL, p = 0.0003) were evident with empagliflozin. No difference was detectable in either LV-GLS at 1 month (empagliflozin vs sitagliptin: + 0.44; [− 0.10/+ 0.98]%, p = 0.11) and 6 months of therapy (+ 0.53; [− 0.56/+ 1.62]%), or in VO_2peak (+ 0.43; [− 1.4/+ 2.3] mL/min/kg, p = 0.65). With empagliflozin, the subgroup with baseline LV-GLS below the median experienced a greater increase (time*drug p < 0.05) in LV-GLS at 1 month (+ 1.22; [+ 0.31/+ 2.13]%) and 6 months (+ 2.05; [+ 1.14/+ 2.96]%), while sitagliptin induced a modest improvement in LV-GLS only at 6 months (+ 0.92; [+ 0.21/+ 0.62]%).

Conclusions

Empagliflozin has neutral impact on both LV-GLS and exercise tolerance in subjects with T2D and normal left ventricular function. However, in patients with subclinical dysfunction (LV-GLS < 16.5%) it produces a rapid and sustained amelioration of LV contractility.

Trial registration EUDRACT Code 2016-002225-10

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01618-1.

Mechanisms of reduced peak oxygen consumption in subjects with uncomplicated type 2 diabetes

Background

Type 2 diabetes mellitus (T2D) increases the risk of incident heart failure (HF), whose earliest fingerprint is effort intolerance (i.e. impaired peak oxygen consumption, or VO_2peak). In the uncomplicated T2D population, however, the prevalence of effort intolerance and the underpinning mechanistic bases are uncertain. Leveraging the multiparametric characterization allowed by imaging-cardiopulmonary exercise testing (iCPET), the aim of this study is to quantify effort intolerance in T2D and to dissect the associated cardiopulmonary alterations.

Methods

Eighty-eight adults with well-controlled and uncomplicated T2D and no criteria for HF underwent a maximal iCPET with speckle tracking echocardiography, vascular and endothelial function assessment, as well as a comprehensive biohumoral characterization. Effort intolerance was defined by a VO_2peak below 80% of maximal predicted oxygen uptake.

Results

Forty-eight patients (55%) had effort intolerance reaching a lower VO_2peak than T2D controls (16.5 ± 3.2 mL/min/kg, vs 21.7 ± 5.4 mL/min/kg, p < 0.0001). Despite a comparable cardiac output, patients with effort intolerance showed reduced peak peripheral oxygen extraction (11.3 ± 3.1 vs 12.7 ± 3.3 mL/dL, p = 0.002), lower VO₂/work slope (9.9 ± 1.2 vs 11.2 ± 1.4, p < 0.0001), impaired left ventricle systolic reserve (peak S’ 13.5 ± 2.8 vs 15.2 ± 3.0, p = 0.009) and global longitudinal strain (peak-rest ΔGLS 1.7 ± 1.5 vs 2.5 ± 1.8, p = 0.03) than subjects with VO_2peak above 80%. Diastolic function, vascular resistance, endothelial function, biohumoral exams, right heart and pulmonary function indices did not differ between the two groups.

Conclusions

Effort intolerance and reduced VO_2peak is a severe and highly prevalent condition in uncomplicated, otherwise asymptomatic T2D. It results from a major defect in skeletal muscle oxygen extraction coupled with a subtle myocardial systolic dysfunction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01314-6.

Type 2 diabetes and reduced exercise tolerance: a review of the literature through an integrated physiology approach

The association between type 2 diabetes mellitus (T2DM) and heart failure (HF) is well established. Early in the course of the diabetic disease, some degree of impaired exercise capacity (a powerful marker of health status with prognostic value) can be frequently highlighted in otherwise asymptomatic T2DM subjects. However, the literature is quite heterogeneous, and the underlying pathophysiologic mechanisms are far from clear. Imaging-cardiopulmonary exercise testing (CPET) is a non-invasive, provocative test providing a multi-variable assessment of pulmonary, cardiovascular, muscular, and cellular oxidative systems during exercise, capable of offering unique integrated pathophysiological information. With this review we aimed at defying the cardiorespiratory alterations revealed through imaging-CPET that appear specific of T2DM subjects without overt cardiovascular or pulmonary disease. In synthesis, there is compelling evidence indicating a reduction of peak workload, peak oxygen assumption, oxygen pulse, as well as ventilatory efficiency. On the contrary, evidence remains inconclusive about reduced peripheral oxygen extraction, impaired heart rate adjustment, and lower anaerobic threshold, compared to non-diabetic subjects. Based on the multiparametric evaluation provided by imaging-CPET, a dissection and a hierarchy of the underlying mechanisms can be obtained. Here we propose four possible integrated pathophysiological mechanisms, namely myocardiogenic, myogenic, vasculogenic and neurogenic. While each hypothesis alone can potentially explain the majority of the CPET alterations observed, seemingly different combinations exist in any given subject. Finally, a discussion on the effects -and on the physiological mechanisms-of physical activity and exercise training on oxygen uptake in T2DM subjects is also offered. The understanding of the early alterations in the cardiopulmonary response that are specific of T2DM would allow the early identification of those at a higher risk of developing HF and possibly help to understand the pathophysiological link between T2DM and HF.