Impact of Extreme Heat on Myocardial Blood Flow and Flow Reserve in Young and Older Adults

NCT06842784 | Recruiting

• 2 other identifiers: STU_2019_1759_MCE1R01AG069005
• Study Type: observational
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

Extreme heat causes a disproportionate number of hospitalizations and deaths in older adults relative to any other age group. Importantly, many hospitalizations and deaths are primarily due to cardiovascular events such as myocardial infarction. Previous data indicate that older adults have attenuated skin blood flow and sweating responses when exposed to heat, resulting greater increase in core body temperature. Despite these observations, relatively little is known about the risk for myocardial ischemia potentially contributing to the aforementioned higher morbidity and mortality in older adults during heat waves. The broad objective of this work is to determine the impact of ambient heat exposure on myocardial blood flow and flow reserve in young and older adults. Aim 1 will test the hypothesis that older adults exhibit attenuated myocardial flow reserve compared to young adults during heat stress. Aim 2 will determine if the percent of maximal myocardial flow reserve (assess via vasodilator stress) during heat exposure is higher in older adults compared to young adults. The expected outcome from this body of work will improve our understanding of the consequences of aging on cardiovascular responses to ambient heat stress.

Conditions

Aging; Heat Stress; Hyperthermia; Heat Strain

Outcome Measures

Primary Outcomes (2)

• Myocardial flow reserve

  Measured via myocardial contrast echocardiography.

  The difference in the change from baseline to a vasodilator stress test and the change from baseline to after 3-hours of heat stress.

• Myocardial blood flow

  Measured via myocardial contrast echocardiography.

  The change from baseline to after 3 hours of heat stress.

Secondary Outcomes (4)

• Core temperature

  The change from baseline to after 3 hours of heat stress..

• Indices of left and right ventricular function

  At baseline and after 3 hours of heat stress.

• Heart rate

  At baseline, during exercise- after 20 minutes and 2 hours in the heat, and at rest after 3 hours of heat stress.

• Blood pressure

  At baseline, during exercise- after 20 minutes and 2 hours in the heat, and at rest after 3 hours of heat stress.

Study Arms (2)

Young participants

Individuals aged 18-39 years

Other: Ambient heat stress

Older participants

Individuals aged 65 years or older

Other: Ambient heat stress

Interventions

Ambient heat stress OTHER

3-hour ambient heating in 44°C and 20% relative humidity

Older participants; Young participants

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

The study population will be healthy younger and older individuals identified from the general population.

You may qualify if:

• Healthy male and female individuals
• years or 65+ years of age
• Free of any underlying moderate to serious medical conditions

You may not qualify if:

• Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, uncontrolled hypertension, and uncontrolled hypercholesterolemia.
• Taking of any medications (such as beta blockers and non-dihydropyridine calcium channel blockers) that have known influences on either cardiac function or sweating responses.
• Abnormalities detected on routine screening.
• Current smokers, as well as individuals who regularly smoked within the past 3 years.
• Body mass index of greater than 30 kg/m\^2
• Pregnant individuals

Sponsors & Collaborators

• University of Texas Southwestern Medical Center: lead
• National Institute on Aging (NIA): collaborator
• The American Society of Echocardiography: collaborator

Study Sites (1)

Texas Health Presbyterian Hospital Dallas

Dallas, Texas, 75231, United States

RECRUITING

MeSH Terms

Conditions

Heat Stress Disorders; Hyperthermia

Condition Hierarchy (Ancestors)

Wounds and Injuries; Body Temperature Changes; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Zachary McKenna, PhD

CONTACT

214-345-6557; ZacharyMckenna@texashealth.org

Taysom Wallace, MS

CONTACT

214-345-5022; TaysomWallace@texashealth.org

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Study Record Dates

• First Submitted: February 18, 2025
• First Posted: February 24, 2025
• Study Start: February 3, 2025
• Primary Completion: February 1, 2026
• Study Completion (Estimated): February 1, 2027
• Last Updated: February 24, 2025

Record last verified: 2025-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)