A comprehensive assessment of factors influencing heart rate response during exercise stress and subsequent recovery among patients undergoing TMT

The study titled “A Comprehensive Assessment of Factors Influencing Heart Rate Response During Exercise Stress and Subsequent Recovery Among Patients Undergoing TMT” is a prospective cross-sectional study conducted by the Department of Cardiology and the Department of Cardiovascular Technology at Kasturba Medical College , Manipal. The study aims to evaluate the factors influencing heart rate response during exercise stress testing and subsequent recovery among patients undergoing treadmill testing.

The primary objective is to assess the determinants affecting heart rate response during exercise stress and the recovery time following exercise. The secondary objectives are to evaluate ST-segment and QT interval changes associated with heart rate response and to assess blood pressure  response in relation to heart rate variations.

Exercise stress testing using the Treadmill Test  is a widely used non-invasive diagnostic tool for evaluating cardiovascular function and detecting ischemic heart disease. Heart rate behavior during exercise and its recovery phase serve as important indicators of autonomic nervous system function and cardiovascular fitness. Abnormal responses, such as chronotropic incompetence  or delayed heart rate recovery, have been associated with increased cardiovascular morbidity and mortality. Despite this, there is limited literature particularly in the Indian population examining how modifiable risk factors such as smoking, obesity, diabetes, controlled hypertension, and subclinical thyroid dysfunction influence heart rate response and recovery patterns. This study seeks to address this gap.

The study period will be from February 2026 to January 2027. Approximately 90 to 100 patients undergo TMT each month in the Department of Cardiology. As a time-bound study, an estimated 1,200 participants  will be included.Inclusion criteria comprise adults aged above 18 years undergoing TMT using the Bruce protocol. Both male and female participants will be included to allow gender-based comparisons. Patients with common cardiovascular risk factors such as obesity, diabetes, controlled hypertension, and subclinical thyroid dysfunction will be eligible. Exclusion criteria include unwillingness to provide consent, use of medications that significantly alter heart rate , and TMT performed using protocols other than Bruce.

The study will follow a structured clinical workflow. Patients referred for routine TMT and willing to participate will be recruited after obtaining informed consent. Baseline parameters such as heart rate, blood pressure, ECG findings, medical history, occupation, and lifestyle factors will be recorded. During the test, heart rate at each minute of exercise, time taken to reach target heart rate , peak heart rate, maximum blood pressure, maximum workload achieved and time taken for heart rate recovery will be documented. Additional ECG parameters including ST-segment elevation or depression and QT interval changes will be noted. The final TMT result  will also be recorded.

All parameters will be obtained during routine TMT without any additional procedures, drugs, or costs to the patient. The test will be conducted using the GE CASE Treadmill system under cardiologist supervision. In case of emergencies, patients will be managed according to hospital protocol.

Data will be entered into Microsoft Excel and analyzed using Excel and Jamovi software.

Outcome measures include demographic details like age, gender, occupation, cardiovascular risk factors, baseline heart rate and blood pressure, age-predicted maximum heart rate , target heart rate , heart rate reserve, maximum workload, peak blood pressure, time to reach target heart rate, heart rate recovery time, ST-segment changes, QT interval duration, and overall TMT result.

The study poses minimal risk as it is observational and utilizes routine diagnostic testing. There are no additional interventions beyond standard clinical care. Potential benefits include improved understanding of how modifiable and non-modifiable factors influence heart rate dynamics during exercise. Findings may aid in early identification of abnormal autonomic responses, enhance cardiovascular risk stratification, and support preventive strategies aimed at reducing long-term heart disease, disability, and mortality.

Ethical approval will be obtained from the Institutional Ethics Committee , and CTRI registration will be completed prior to study initiation. Written informed consent will be secured from all participants. Confidentiality of patient data will be strictly maintained, with access limited to authorized personnel. Any presentation or publication arising from the study will not include identifiable patient information.