“Wildfires that spread into urban areas have proven to be extremely dangerous because of how quickly they move and what they burn and release into the environment,” said Susan Cheng, MD, MPH, vice chair of Research Affairs in the Department of Cardiology in the Smidt Heart Institute and senior author of the study, published in JACC. “Our research suggests the Eaton and Pacific Palisades fires had an immediate effect on people’s health.”

The Cedars-Sinai Emergency Department is located on the academic medical center’s main campus, about 10 miles from Pacific Palisades and about 20 miles from Altadena, the locations where the largest L.A. fires ignited in January 2025. Investigators collected data on emergency department visits during the 90 days after the fires started, from Jan. 7 to April 7, 2025. They compared this data with emergency visit data collected during the same calendar period in the years 2018 through 2024. 

Although there wasn’t a significant difference in total emergency department visits during the first 90 days following the start of the wildfires in 2025 as compared with other years, there was a drastic increase in emergency department visits for certain conditions. Investigators found a 118% increase in visits for general illness, 46% increase in the number of visits for heart attack, and a 24% increase in visits for pulmonary illness when compared to the average rate of these conditions diagnosed during the same time window in the past seven years. 

“Fine particles released by wildfires can enter the body and cause injury, particularly to the heart and lungs,” said Cheng, who is also the Erika J. Glazer Chair in Cardiovascular Health and Population Science in the Smidt Heart Institute at Cedars-Sinai. “Stress related to the fires may also contribute to a broad range of health issues.” 

The investigators found that abnormal blood test results related to general illness more than doubled in the 90-day period in 2025 as compared with that period in previous years. This is a finding not previously reported after major wildfires, according to the investigators.

“Abnormal blood test results could indicate that the body is responding to an external stressor such as toxins in the air,” said Joseph Ebinger, MD, MS, associate professor in the Department of Cardiology and first author of the study. “This study is an important step toward understanding how the Eaton and Palisades fires may have affected Angelenos’ health. We need more research to determine what we can do to mitigate any remaining risks and protect people from fire harm in the future.” 

This study is part of the larger LA Fire HEALTH Study, a research collaboration that seeks to determine the health effects of the fires that ignited in January 2025 in L.A. County. Investigators with Cedars-Sinai; the Harvard T.H. Chan School of Public Health; the Keck School of Medicine of the University of Southern California (USC); Stanford University; UCLA; the University of California, Davis (UCD); the University of California, Irvine (UCI); the University of Texas at Austin; and Yale University plan to study the impacts of the fires for the next 10 years. 

Additional Cedars-Sinai authors include Tzu Yu Huang, MS; Sandy Joung, MSHS, MBA; Juliane Kwong, BS; Wasay Warsi, MS, BS; Nancy Sun, MPS; Jesse Navarrette, MPA; Patrick Botting, DHSc; Zaldy S. Tan, MD, MPH; and Alan C. Kwan, MD.

Other authors include Brian L. Claggett, PhD, of Brigham and Women’s Hospital in Boston.

Funding: This work was partially supported by the Spiegel Family Fund, the Smidt Heart Foundation, and the Erika J. Glazer Family Foundation. 

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Novel research from investigators in the Smidt Heart Institute at Cedars-Sinai, published today in the peer-reviewed journal Hypertension, found that aRH prevalence was lower in a real-world sample than previously reported, but still relatively frequent—affecting nearly 1 in 10 hypertensive patients.

Through their analysis, investigators also learned that patients with well-managed aRH were more likely to be treated with a commonplace medication called mineralocorticoid receptor antagonist, or MRA. These MRA treatments were used in 34% of patients with controlled aRH, but only 11% of patients with uncontrolled aRH.

“Apparent resistant hypertension is more common than many would anticipate,” said Joseph Ebinger, MD, assistant professor of Cardiology in the Smidt Heart Institute and corresponding author of the study. “We also learned that within this high-risk population, there are large differences in how providers treat high blood pressure, exemplifying a need to standardize care.”

Study findings were based on a unique design, which used clinically generated data from the electronic health records of three large, geographically diverse healthcare organizations. Of the 2,420,468 patients analyzed in the study, 55% were hypertensive. Of these hypertension patients, 8.5%, or 113,992 individuals, met criteria for aRH.

According to Ebinger, treating aRH can be just as tricky as diagnosing it.

In fact, the “apparent” in apparent resistant hypertension stems from the fact that before diagnosis, medical professionals must first rule out other potential reasons for a patient’s blood pressure to be high.

These reasons might include medication non-adherence, inappropriate medication selection, or artificially elevated blood pressure in the doctor’s office—known as “white coat hypertension.”

“Large amounts of data tell us that patients with aRH, compared to those with non-resistant forms of hypertension, are at greatest risk for adverse cardiovascular events,” said Ebinger, director of Clinical Analytics in the Smidt Heart Institute. “Identifying these patients and possible causes for their elevated blood pressure is increasingly important.”

The takeaway, Ebinger says, is awareness—for both medical professionals and patients. He says providers should be mindful that if it’s taking four or more antihypertensive medications to control a patient’s blood pressure, they should consider evaluation for alternative causes of hypertension, or refer patients to a specialist.

Similarly, patients should lean on their medical providers to help them navigate the complex disease, including having a conversation around strategies for remembering to take their medication and addressing possible treatment side effects.

Treating patients with complex cardiac issues like aRH is at the heart of Cedars-Sinai’s expertise.

The Smidt Heart Institute was recently awarded the American Heart Association’s Comprehensive Hypertension Center Certification, recognizing the institute’s commitment to following proven, research-based treatment guidelines to care for people with complex or difficult-to-treat hypertension.

“This accreditation, coupled with our clinical and research expertise in hypertensive diseases, serves as a mark of excellence,” said Christine M. Albert, MD, MPH, chair of the Department of Cardiology and the Lee and Harold Kapelovitz Distinguished Chair in Cardiology. “These efforts signal to patients, healthcare providers, and the community that the Smidt Heart Institute is committed to delivering evidence-based, comprehensive care for hypertension.”

Funding: This work was supported in part by Cedars-Sinai Medical Center and by the National Institutes of Health grant K23-HL153888.

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