Effect of Treadmill Test According to Bruce Protocol Stage 1 on Left Ventricular Diastolic Function in Patients with Exertional Dyspnea and Normal Left Ventricular Function

Abstract

ABSTRACT Introduction: Diastolic dysfunction, detected commonly by echocardiography is the fore-runner of Heart Failure (HF) with preserved Ejection Fraction (HFpEF) in future. Exercise stress by Treadmill Test (TMT) followed by echocardiography can unmask sub-clinical diastolic dysfunction. Aim: To estimate the proportion of patients with unexplained exertional dyspnea that had sub-clinical diastolic dysfunction and to find out the factors associated with it. Materials and Methods: This institution-based cross-sectional study, included participants with history of unexplained exertional dyspnea having normal baseline electrocardiogram and echocardiogram (N=106). Patients having serious co-morbidities like azotemia, decompensated liver disease, malignancy and also individuals who did not give consent were excluded. Included individuals were subjected to exercise stress by TMT Bruce protocol stage 1. Postexercise echocardiography was done to find out proportion of patients showing diastolic dysfunction in postexercise echocardiogram. Factors associated with unmasking of sub-clinical diastolic dysfunction were assessed by logistic regression analysis. Results: Postexercise echocardiography revealed diastolic dysfunction in 33 individuals (31.13%). On multivariate analysis, diabetes and hypothyroidism were significant predictors of exercise-induced diastolic dysfunction. The appearance of diastolic dysfunction was due to changes in mitral inflow E/A ratio and pulmonary vein systolic flow/diastolic flow (S/D) ratio in postexercise echocardiogram. Conclusion: Exercise stress can unmask sub-clinical diastolic dysfunction in significant number of patients.

Keywords

• diastolic dysfunction
• diastolic stress test
• ejection fraction
• heart failure