COPD overdiagnosis puts valve replacement benefits at risk
medwireNews: A study shows that pulmonary function improves following aortic valve replacement in a substantial proportion of patients preoperatively diagnosed with chronic obstructive pulmonary disease (COPD), suggesting they may have misdiagnosed chronic heart failure.
As severe COPD is sometimes considered a contraindication for the surgery, this could lead to such patients missing out on a procedure that could, in fact, ameliorate their pulmonary symptoms, caution the researchers from the Medical City Dallas Hospital in Texas, USA.
“Overestimating the severity of COPD in patients with [aortic stenosis] may inadvertently deny patients life-saving surgery, while underestimating COPD may result in inaccurate risk assessment of perioperative morbidity and mortality of [aortic valve replacement] related to COPD,” they comment in the Annals of Thoracic Surgery.
The researchers studied the outcomes of 214 consecutive patients with severe aortic stenosis who were taking part in a clinical trial of valve replacement between January 2009 and July 2011.
During preoperative pulmonary function tests, 143 (66.8%) patients were diagnosed with COPD, of whom 52 were classified as mild, 42 as moderate, and 49 as severe.
Six to 12 months after aortic valve replacement, repeat pulmonary function testing in 71 of the patients showed that 40%, 43%, and 45% of patients with mild, moderate, and severe COPD, respectively, had improved by at least one COPD severity class (defined by The Society of Thoracic Surgeons Adult Cardiac Surgery Database risk assessment algorithm).
Postoperative forced expiratory volume in 1 second (FEV1) improved by at least 10% in 42%, 50%, and 50% of patients, respectively.
Such a change in lung function, the team explains, would be not be expected in patients with underlying chronic lung disease, but would be anticipated in those with chronic heart failure.
“This raises the question of whether [pulmonary function tests] alone are the most accurate way to diagnose and risk-stratify such patients,” comments the team, led by Mitchell Magee.
Noting they observed a significant association between improved postoperative B-type natriuretic peptide (BNP) levels and FEV1, the authors suggest that BNP could be used as an additional marker in surgical patients to help distinguish COPD from chronic heart failure.
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By Kirsty Oswald, medwireNews Reporter