Assess Cardiac Risks in Amputee Patients

Coronary artery calcium score detected a greater burden of underlying atherosclerotic disease in amputees compared with control participants matched by Framingham risk stratification, according to a recent study published in the American Academy of Physical Medicine & Rehabilitation journal, PM&R.

“Despite advances in health care, the long-term survival rate in amputees has not changed in the past 4 decades. Even perioperative mortality rate is surpassing that of high risk cardiac surgeries,” Mallikarjuna Nallegowda, MD, DNB, MNAMS, Physiatrist and Pain medicine fellow in the department of anesthesiology of the division of pain medicine at the University of Michigan, told O&P Business News. “Despite these alarming trends, in the past 4 decades, less work has been done on the need for routine cardiac risk assessment, preoperative cardiac screening or in-depth cardiac evaluation in asymptomatic amputees to decrease the high cardiac mortality and morbidity rates. This study has objectively evaluated population based on cardiovascular risk scores and the prevalence of coronary artery calcification score in amputees.”

Study results

Seventy-six amputees who underwent cardiac computed tomography at the VA Loma Linda Health Care System, Loma Linda, Calif., from 2004 to June 2011 participated, as well as a similar number of age-, gender- and Framingham Risk Score-matched control participants. Control group 1 included participants with known risk factors including diabetes, while control group 2 had all risk factors without diabetes. Researchers assessed statistical associations between amputee and control group Framingham Risk Stratification Scores, coronary artery calcium scores (CACS) and other cardiac risk factors.

According to Framingham Risk Stratification, 66 amputees were in the low-to-intermediate cardiac risk groups. However, despite this classification, the mean CACS were significantly higher in amputees than in either of the control groups. Study results also showed the participants with non-traumatic amputations (ie, due to diabetes) also had significantly higher CACS compared with the traumatic amputee group. After categorizing CACS based on the probability of coronary artery disease, researchers found that 76% of amputees had a CACS greater than 100 (moderate risk) and 38% of amputees had a CACS greater than 1,000 (high risk). Compared with transfemoral amputees, CACS were almost the same in finger/toe amputees. Researchers said this indicated an already ongoing coronary artery disease process despite the level of amputation.

Study results showed that, in amputees, the predominant clinical significant cardiac risk factors are hypertension, chronic kidney disease, dyslipidemia and insulin resistance. Total cholesterol, low-density lipoprotein and high-density lipoprotein were nonsignificantly low in all amputees. In traumatic patients, triglycerides were significantly higher compared with nontraumatic patients.

“With the exception of one study, our findings demonstrated that CACS in amputees are much higher than any other high risk population. Despite similar age and risk matched controls, amputees have high CACS, indicating extensive coronary artery disease,” Nallegowda said. “Other than traditional risk factors, we believe there may be many other unknown factors also contributing for this, including lack of physical activity and exercise.”

Early detection methods

The researchers believe that more prospective studies could help provide valuable insight regarding the relationship between amputees and accelerated coronary artery disease. All amputees should also be carefully evaluated preoperatively for asymptomatic coronary artery disease using an advanced atherosclerotic imaging technique and undergo prophylactic revascularization interventions if necessary.

To minimize morbidity and mortality in amputees, Nallegowda concluded that “national medical societies should consider comprehensive amputee rehabilitation guidelines to include preoperative cardiac screening and targeted interventions with comprehensive medical and aggressive lifestyle treatments.”

According to the researchers, all these measures may reduce unnecessary post-amputation cost, as well as improve the quality of life of amputees. — by Casey Murphy

For more information:
Nallegowda M. PM R. 2012;4:657-666.

Disclosure: Nallegowda has no relevant financial disclosures.

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