Srinivas Mummadi

Heart Rate Recovery Predicts Clinical Worsening in Patients with Pulmonary Arterial Hypertension

RATIONALE Reduced heart rate recovery after exercise is associated with increased mortality in cardiopulmonary diseases. OBJECTIVES We sought to evaluate the association between heart rate recovery at 1 minute of rest (HRR1) after 6-min walk test (6MW test) and clinical worsening in patients with idiopathic pulmonary arterial hypertension (IPAH). METHODS HRR1 was defined as the difference in heart rate at the end of 6MW test and at 1 minute after completion of the 6MW test. Between August 1, 2009 and March 30, 2010, 75 consecutive patients with IPAH underwent 6MW test and were included in the analysis. MEASUREMENTS AND MAIN RESULTS Compared with patients with HRR1 ≥ 16 (n = 45 [60%]), those with HRR1 less than 16 (n = 30 [40%]) were more likely to have clinical worsening (odds ratio, 9.7; 95% confidence interval [CI], 3-30; P < 0.001) and shorter time to first clinical worsening event (TCW) (6.7 mo vs. 13 mo; P < 0.001) during follow-up. By multivariable analysis, the best predictors of clinical worsening were HRR1 less than 16 (hazard ratio, 5.2; 95% CI, 1.8-14.8; P = 0.002) and mean pulmonary arterial pressure (hazard ratio, 1.04; 95% CI, 1.007-1.08; P = 0.02). Compared with the distance walked during the 6MW test (6MWD), HRR1 less than 16 was a better predictor of clinical worsening (C statistic 0.757 vs. 0.703) and TCW (C index 0.730 vs. 0.696). The addition of HRR1 increased the ability of 6MWD to predict clinical worsening events. CONCLUSIONS HRR1 after 6MW test is a strong predictor of clinical worsening and TCW in patients with IPAH. The addition of HRR1 to 6MWD increases the capacity of 6MWD to predict clinical worsening and TCW in patients with IPAH.

Update on Exhaled Nitric Oxide in Clinical Practice

Asthma is characterized by chronic airway inflammation. Fractional exhaled nitric oxide (Feno) has emerged as a marker of T-helper cell type 2-mediated allergic airway inflammation. Recent studies suggest a role for Feno testing as a point-of-care tool in the management of patients with asthma. This Topics in Practice Management article reviews current coverage and reimbursement issues related to Feno testing and provides an overview of pertinent recent studies.

Clinically Significant Variability of Serum IgE Concentrations in Patients with Severe Asthma

Objective. To determine the magnitude of immunoglobulin E (IgE) variability in a cohort of patients with severe asthma considered for omalizumab therapy. Methods. Retrospective chart review identified 65 patients with two or more IgE determinations out of the 124 patients referred to the Cleveland Clinic Respiratory Institute for treatment with omalizumab from 2003 to 2011. Patients with conditions known to affect IgE concentrations were excluded. Demographic data, pulmonary function testing, medications, smoking status, and atopy were recorded. The range of variability and percent variability in relation to baseline serum IgE were calculated. Results. The median difference of serum IgE between the minimal and maximal values was 94.9 IU/ml (IQR 26.3–324.1 IU/ml). Percent variability from minimum value had a median of 75.5% (IQR 23.3–152.6%). There was no correlation between age, body mass index, lung function, and IgE variability. Greater variability was associated with female gender (p = .06). There was no association with peripheral eosinophilia, systemic corticosteroid use, and leukotriene modifier use at presentation. The observed variability would have affected omalizumab dosing in 20 out of 42 patients. Six patients who may have qualified at different time points would not have been deemed candidates based on an IgE concentration <30 IU/ml or >700 IU/ml. Conclusion. Serum IgE concentration may have clinically significant variability over time, affecting candidacy and dosing of omalizumab. Our findings imply that repeating serum IgE determinations merits consideration for patients whose initial concentrations are <30 or >700 IU/ml. Prospective studies are warranted to delineate the factors that contribute to IgE variability.