New breathprint test can predict heart failure
Acute decompensated heart failure (ADHF) is the most common reason for hospital admission, particularly in seniors; however, identifying at-risk individuals before symptoms become evident has been inadequate. Now, a new breathprint test, using a single exhaled breath, can detect impeding heart failure. The test could lead to interventions that could reduce the need for hospitalization. Researchers affiliated with the Cleveland Clinic published their findings in the April edition of the Journal of the American College of Cardiology.
The researchers note that previous studies have identified elevated acetone, pentane, and nitric oxide levels in the exhaled breath of heart failure patients correlated with disease severity. A technique known as selected ion-flow tube mass-spectrometry (SIFT-MS) combines a fast flow tube technique with quantitative mass spectrometry that is ideally suited for exhaled breath analysis because it allows for the analysis of small and humid samples without the need for cumbersome sample preparation or calibration. In addition, scan times are relatively brief. Using this technology, the investigators conducted a prospective (forward-looking) study to evaluate the feasibility of exhaled breath analysis to identify patients admitted for ADHF.
The study group comprised 25 consecutive patients admitted with ADHF as their primary diagnosis and a control group of 16 subjects admitted with non-ADHF cardiovascular diagnoses and who had no clinical evidence of systemic or venous congestion at the time of enrollment. (Venous congestion is indicative of heart failure because the heart is inefficiently pumping out blood.) Indications for hospitalization in the control group included unstable angina or myocardial infarction (6 of 16), conduction disorders (3 of 16), hypertensive emergency (3 of 16), atrial tachyarrhythmia (2 of 16), or stable angina (2 of 16). The investigators found no significant differences between the groups in age, body mass index (BMI), or several comorbidities (i.e., diabetes mellitus, chronic obstructive pulmonary disease (COPD), active smoking). These conditions have been theorized to alter the contents of an exhaled breath,
Exhaled breath samples were collected within 24 hours of hospital admission and following an eight-hour fast and before the administration of morning medications. Samples were collected after a tap water mouth rinse to standardize the breath samples. The patients exhaled a single breath into a sterile mouthpiece while attempting to maintain an exhaled pressure of 15 millibars. All breath analyses were performed within two hours. Sample collection was well tolerated even among patients with disease severity warranting intensive care unit admission and invasive cardiovascular monitoring. Confirming previous reports, the investigators observed increased exhaled acetone and pentane in ADHF patients, compared to the control group. In addition, mass scanning of ion products for hydronium, oxygen, and nitrous oxide further distinguished ADHF patients from control patients. This breathprint was then tested in an independent validation test on 36 consecutive ADHF patients with identical enrollment criteria to the study group.
The researchers concluded that the test needs further refinement before it can be used in the clinical setting. They noted that the exhaled metabolome is a temporally dynamic complex mixture (a mixture that changes over time); therefore breath analysis is highly susceptible to the confounding effects of timing and context of sample collection. In addition, methods of metabolomic data analysis are still being formalized and will need to be refined to facilitate reproducibility and generalizability of future studies. (Metabolome refers to the complete set of metabolic products to be found within a biological sample (in tis case, a breath sample)). In addition, the results of this study are limited by the small sample size, and larger prospective studies are needed to validate these results. Despite the foregoing, the investigators note that their findings demonstrate the feasibility of single exhaled breath analysis in ADHF. In addition, they validated the previously reported alterations in acetone and pentane concentrations in ADHF, and provided pilot evidence to support the hypothesis that a unique ADHF breathprint exists. They wrote: Like conventionally available exhaled breath sensors, the promise of this technology lies in the potential for point-of-care and ambulatory monitoring and screening. Future studies in exhaled breath metabolomics are needed to accelerate progress in the field of cardiovascular medicine.”