Science
Weight loss in obesity-related heart failure may help reverse dysfunction
Clinical takeaway: Treatment for weight loss may help restore underlying myocardial function in severely obese patients with heart failure with preserved ejection fraction, though further research is needed.
Heart failure with preserved ejection fraction (HFpEF) has usually been framed as a disorder of stiffness and impaired filling. These findings point to a different biology in severe obesity, where the heart muscle itself appears weaker and may have less reserve during exertion.
Researchers analyzed heart muscle samples from patients with this condition and found that the most obese group had substantially weaker force generation, lower power, and poorer responses to calcium and stretch. Those abnormalities more closely resembled advanced heart failure with reduced ejection fraction than the classic preserved-ejection-fraction pattern.
The most clinically relevant signal came from a small subgroup of 16 patients who'd received treatment aimed at reducing body mass, mostly with GLP-1 receptor agonists, for a median of about 1.5 years before biopsy. Greater BMI reduction was associated with better heart muscle cell force, and the patients with the largest reductions generally had contraction closer to the less obese subgroup.
The study identified a possible mechanism. Troponin I helps regulate how the sarcomere, the heart muscle’s basic contractile unit, generates force. In the severely obese heart failure group, phosphorylation of troponin I increased with BMI in failing hearts but remained low in nonfailing hearts, and experimental modeling suggested that this change itself could weaken force generation. That raises the potential for pairing metabolic treatment with therapies aimed more directly at sarcomere dysfunction.
“HFpEF has long been viewed as a stiffness problem,” said David Kass, MD, the Abraham and Virginia Weiss Professor of Cardiology at the Johns Hopkins University School of Medicine. “Our study shows a distinct picture in patients with severe obesity: The muscle itself can be weaker, driven by a specific chemical change in a contraction protein, opening possibilities for targeted treatment.”
Heart failure affects about 6.6 million people in the United States, and nearly half have HFpEF, a form with roughly 20% to 29% one-year mortality. Obesity has become a major feature of HFpEF, increasingly supplanting the prior hypertension-dominant phenotype.
Source: Jani VP. Science. 2026 Apr 23. Severe Obesity in Human HFpEF Alters Contractile Protein Function and Organization