The serum heavy/light chain immunoassay: A valuable tool for sensitive paraprotein assessment, risk, and disease monitoring in monoclonal gammopathies.

OBJECTIVE: The heavy/light chain (HLC)-immunoassay quantifies light chain types of each immunoglobulin class in patients with monoclonal gammopathies. METHODS: We assessed 147 consecutive patients with different forms and stages of plasma cell dyscrasias (PCD) who received standard tests (serum and urine protein electrophoresis [SPEP, UPEP], immunofixation [IFE], serum-free light chain [SFLC]), and HLC-immunoassay. Patients with multiple myeloma (MM, n = 102), smoldering MM (SMM, n = 5), monoclonal gammopathy of undetermined significance (MGUS, n = 28), and Waldenström's macroglobulinemia (WM, n = 12) were included. RESULTS: We verified a significant correlation between HLC- and standard monoclonal protein (mp)-parameters, and HLC-increases with higher disease stage and unfavorable remission status. In patients with difficult to quantify mp, more abnormal HLC- than SPEP-, immunoglobulin-, or SFLC-results were found. In WM, a pathological HLC κ/λ-ratio and M-component were observed in 95% and 58%, respectively. In 21/28 MGUS and 5/5 SMM patients, HLC κ/λ-ratios were abnormal. Testing different HLC cutoffs, patients with extreme HLC values showed impaired progression-free survival (PFS). CONCLUSIONS: Despite the fact that different PCD patients were included, the assessment of the HLC-immunoassay in MGUS, SMM, MM, and WM, our comparison with standard mp-assays, and relevant PFS differences may excite future applications, which should be confirmed in prospective multicenter trials.

Evaluation of a 1-hour troponin algorithm for diagnosing myocardial infarction in high-risk patients admitted to a chest pain unit: the prospective FAST-MI cohort study.

OBJECTIVE: This study sought to evaluate the diagnostic performance of the 1-hour troponin algorithm for diagnosis of myocardial infarction (MI) without persistent ST-segment elevations (non-ST-segment MI (NSTEMI)) in a cohort with a high prevalence of MI. This algorithm recommend by current guidelines was previously developed in cohorts with a prevalence of MI of less than 20%. DESIGN: Prospective cohort study from November 2015 until December 2016. SETTING: Dedicated chest pain unit of a single referral centre. PARTICIPANTS: Consecutive patients with suspected MI were screened. Patients with subacute symptoms lasting more than 24 hours, new ST-segment elevations at presentation, or an already diagnosed or ruled-out acute MI were excluded. All enrolled patients (n=1317) underwent a full clinical assessment and measurements of high-sensitivity troponin, and were scheduled for an early invasive strategy if clinically indicated. MAIN OUTCOME MEASURES: Final diagnosis of MI according to the Fourth Universal Definition of MI. RESULTS: The prevalence of NSTEMI in the present cohort was 36.9%. The sensitivity for rule-out of MI was 99.8%. The specificity for rule-in of MI was found to be 94.3%. However, in 35.7% of patients neither rule-in nor rule-out was possible. In 51.4% of patients diagnosed with MI, a primary non-coronary reason for MI was found (type 2 MI). Different receiver operating characteristic-curve derived cut-offs for troponin and its dynamics did not provide a sufficient differentiation between type 1 and 2 MI for clinical decision making (negative predictive value for rule-out of type 1 MI <70%). CONCLUSIONS: The 1-hour diagnosis algorithm for patients with suspected NSTEMI can accurately diagnose acute MI in high-risk cohorts. However, discrimination between patients needing an early invasive strategy or not is limited. TRIAL REGISTRATION NUMBER: DRKS00009713.