Morbid Obesity: An Increasing Risk Factor in PCI Patients

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Not only is morbid obesity associated with higher in-hospital mortality among patients undergoing percutaneous coronary intervention (PCI), but the  population is growing rapidly, contributing to a range of patient- and clinician-related issues, according to 2 studies scheduled to be published online June 18, 2013, ahead of print in the Journal of the American College of Cardiology.

In the first study, led by Ramesh Daggubati, MD, of East Carolina University Brody School of Medicine (Greenville, NC), in-hospital outcomes from the National Cardiovascular Data Registry CathPCI Registry were compared between extremely obese (n = 83,861) and normal-weight patients (n = 217,616) who underwent radial or femoral PCI and were discharged between July 2009 and June 2011.

The extreme obesity group had a BMI of 40 or greater, while the normal-weight group had a BMI between 20 and 25.

Extreme Obesity Predicts Mortality

Compared with normal-weight patients, those who were extremely obese were younger, more often female or African American, and had a higher prevalence of diabetes, hypertension, and

hyperlipidemia. While the extremely obese were more likely to have a history of PCI, normal-weight patients had a higher rate of cerebrovascular and peripheral vascular diseases.

After multivariable adjustment, extreme obesity was independently associated with greater mortality overall but lower risk of bleeding. However, when patients were stratified according to whether they had STEMI or NSTEMI, extreme obesity remained independently associated with higher mortality only in the STEMI subgroup. Bleeding was reduced across the board (table 1).

Table 1. In-Hospital Outcomes: Extreme Obesity vs. Normal Weight

Transradial access was used more often in extremely obese patients than in the normal-weight group (10% vs. 5%; P < 0.0001). However, the interaction between femoral vs. radial access and outcomes was not statistically significant (P = 0.10 for bleeding, 0.70 for mortality). In stratified analysis, and in unadjusted and multivariable adjusted models, bleeding complications were lower for extremely obese compared with normal-weight patients in both the femoral and radial subgroups.

No ‘Obesity Paradox’ for Extremely Obese

According to the study authors, 2 unmeasured factors may explain the increased risk of in-hospital mortality associated with obesity and STEMI: pulmonary embolism and difficulties with airway management. Additionally, they suggest that difficulties with obtaining venous or arterial access in extremely obese patients may be associated with increased complications, although there are few data to support that theory.

As for the decreased risk of bleeding in these patients, Dr. Daggubati and colleagues say the finding may “reflect underdosing of anticoagulants, or higher use of closure devices or transradial access.”

The findings are similar to a 2011 study published in the Journal of the American College of Cardiology that showed a relationship between BMI and in-hospital outcomes among STEMI patients in the NCDR ACTION Registry–GWTG, they add.

In an e-mail communication with TCTMD, Carl J. Lavie, MD, of Ochsner Medical Center (New Orleans, LA), said much has been written in recent years about the so-called ‘obesity paradox,’ which suggests that obese patients with cardiovascular disease have a better prognosis than their lean counterparts. However, he noted, “most studies, although not all, typically show that the severe (or extreme) obese, often called Class 3 obese or ‘morbidly obese’ do not do well, and weight reduction is more clearly needed in these patients.”

Additionally, Dr. Lavie clarified that he believes it is more of an ‘overweight paradox,’ in that generally the best prognosis is noted in those who are overweight or mildly obese. Yet another piece of the puzzle is fitness.

“Fitness really impacts the relationship between fatness and prognosis,” Dr. Lavie said. Data from patients with coronary heart disease as well as heart failure, he added, suggest that those who are fit, or at least do not have poor fitness, have a good prognosis. However, patients who have poor fitness have high event rates and show a strong obesity paradox, with the thinnest patients with the lowest fitness having especially poor outcomes.

Rapid Increase in Morbidly Obese PCI Patients

In the second study, Hitinder S. Gurm, MD, of the University of Michigan Cardiovascular Center (Ann Arbor, MI), and colleagues found that the prevalence of patients with morbid obesity undergoing PCI increased by 91% from 1998 to 2009 (from 4.38% to 8.36%). The dataset included 227,044 patients enrolled in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium registry.

Similar to the CathPCI Registry study, morbidly obese patients (BMI > 40) were younger and had a significantly higher incidence of hypertension and diabetes than patients classified as lean (BMI < 25), overweight (BMI 25-30), or sub-morbidly obese (BMI 30-40).

Compared with overweight patients, morbidly obese patients had increased vascular complications (OR 1.31; 95% CI 1.17-1.47), contrast-induced nephropathy (OR 1.89; 95% CI 1.70-2.11), nephropathy requiring dialysis (OR 4.08; 95% CI 2.98-5.59,) and mortality (OR 1.63; 95% CI 1.33-2.00; P < 0.0001 for all).

In a telephone interview with TCTMD, Dr. Gurm said one reason for doing the study was his own experience that the morbidly obese PCI population seemed to be increasing.

“I think this is a wake-up call to society that there has been a 91% increase in the last decade,” he said. “We can’t tell people how to live but . . . pretty much every complication is higher for these patients who are extremely obese. It’s a very complex issue [in terms of] how we should intervene.”

Dr. Gurm said many obese patients are referred for PCI because in addition to the risk of complications, their girth creates issues for surgeons who would otherwise perform CABG. He related a recent case of a colleague who performed successful PCI in a patient with a BMI of 70 and left main disease who had been refused surgery.

“We have to do something for these patients when they are sent to the cath lab, but the ability to even see through that much tissue is difficult,” Dr. Gurm said. He added that in addition to needing larger tables in cath labs to accommodate extremely obese patients, strategies are needed to help interventionalists to minimize their own radiation exposure, since radial access is preferred in patients with a BMI greater than 35 to reduce the risk of bleeding.

 

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Sources:
1. Payvar S, Kim S, Rao SV, et al. In-hospital outcomes of percutaneous coronary interventions in extremely obese and normal weight patients: Findings from the NCDR. J Am Coll Cardiol. 2013;Epub ahead of print.

2. Buschur ME, Smith D, Share D, et al. The burgeoning epidemic of morbid obesity in patients undergoing percutaneous coronary intervention: Insight from the Blue Cross Blue Shield of Michigan cardiovascular consortium. J Am Coll Cardiol. 2013;Epub ahead of print.

 

 

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