‘Obesity paradox’ remains apparent after PCI

Consistent with previous research, registry data from the United Kingdom have linked elevated BMI to reduced mortality after PCI.

“The so-called obesity paradox has been reported in patients undergoing coronary revascularization procedures ... and in those with chronic [HF] and in several other cardiac disease states,” Debabrata Mukherjee, MD, and Chandra Ojha, MD, both from Texas Tech University Health Sciences Center in El Paso, Texas, wrote in an editorial comment accompanying publication of the study findings in JACC: Cardiovascular Interventions. “Holroyd et al examine the relationship between BMI and clinical outcomes following PCI and report that an independent association of elevated BMI to reduced mortality after PCI still exists in contemporary U.K. practice.”

BMI and mortality

The researchers used data from 345,192 participants in the British Cardiovascular Intervention Society registry from 2005 to 2013 to evaluate the association between BMI group and adverse in-hospital outcomes and mortality in patients undergoing PCI.

According to the data, the odds of 30-day mortality were lower in patients with overweight (BMI 25-30 kg/m²; OR = 0.86; 95% CI, 0.8-0.93) and obesity (BMI > 30 kg/m²; OR = 0.9; 95% CI, 0.82-0.98), as compared with normal-weight patients (BMI 18.5-24.9 kg/m²).

Also, compared with normal-weight patients, 1-year mortality was reduced in those with overweight (OR = 0.7; 95% CI, 0.67-0.73) and obesity (OR = 0.73; 95% CI, 0.69-0.77). However, lean patients (BMI < 18.5 kg/m²) had increased odds of mortality at 1 year after PCI (OR = 1.85; 95% CI, 1.63-2.1).

Similar results were seen up to 5 years after PCI for patients with overweight (OR = 0.78; 95% CI, 0.75-0.81) and obesity (OR = 0.88; 95% CI, 0.84-0.92) vs. normal-weight patients.

The relationship between elevated BMI and reduced mortality after PCI was evident across clinical presentations, including stable angina, unstable angina or non-STEMI, and STEMI.

Although patients with obesity were less likely to experience in-hospital bleeding in multivariate analysis, BMI did not appear to affect in-hospital rates of MACE, defined as the composite of in-hospital reinfarction, repeat PCI, CABG and in-hospital mortality, after adjustment for baseline covariates.

The researchers noted that the reduced bleeding in patients with greater BMI may be related to the more frequent use of radial access in these patients (48% vs. 44%) and the potential for anticoagulant dosing issues in patients with low BMI.

More research needed

In light of their findings, the researchers underscored the need for further study of the “obesity paradox.”

“Future research is necessary to understand the pathological mechanism of this effect or identify which confounding variables are missing from the analysis,” they wrote.

“Despite some limitations of this registry study, such as unrecognized confounders, lack of complete data on optimal evidence-based medical therapies across groups, and lack of data on marked recent weight loss and frailty, this large study is consistent with several recent observations,” Murkherjee and Ojha wrote in their editorial. “The study raises important questions regarding implication for these findings and how we translate these observations into meaningful advice for clinical practitioners.” – by Melissa Foster

Disclosure s : The researchers, Mukherjee and Ojha report no relevant financial disclosures.