Parathormone levels add prognostic ability to N-terminal pro-brain natriuretic peptide in stable coronary patients

There are controversial data on the ability of the components of mineral metabolism (vitamin D, phosphate, parathormone [PTH], fibroblast growth factor-23 [FGF23], and klotho) to predict cardiovascular events. In addition, it is unknown whether they add any prognostic value to other well-known biomarkers.

In 969 stable coronary patients, we determined plasma levels of all the aforementioned components of mineral metabolism with a complete set of clinical and biochemical variables, including N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitivity troponin I (hs-TnI), and high-sensitivity C-reactive protein. Secondary outcomes were ischaemic events (any acute coronary syndrome, stroke, or transient ischaemic attack) and heart failure or death. The primary outcome was a composite of the secondary outcomes. Median follow-up was 5.39 years. Age was 60 (52-72) years. Median glomerular filtration rate was 80.4 (65.3-93.1) mL/min/1.73 m² . One-hundred and eighty-five patients developed the primary outcome. FGF23, PTH, hs-TnI, and NT-proBNP were directly related with the primary outcome on univariate Cox analysis, while Klotho and calcidiol were inversely related. On multivariate analysis, only PTH (HR 1.058 [CI 1.021-1.097]; P = 0.002) and NT-proBNP (HR 1.020 [CI 1.012-1.028]; P < 0.001) were independent predictors of the primary outcome but also for the secondary outcome of heart failure or death (HR 1.066 [CI 1.016-1.119]; P = 0.009 and HR 1.024 [CI 1.014-1.034]; P < 0.001, respectively). PTH was the only biomarker that predicted ischaemic events (HR 1.052 [1.010-1.096]; P = 0.016). Patients were divided in two subgroups according to FGF23 plasma levels. PTH retained its prognostic value only in patients with FGF23 levels above the median (>85.5 RU/mL) (P < 0.001) but not in patients with low FGF23 levels (P = 0.551). There was a significant interaction between FGF23 and PTH (P = 0.002). However, there was no significant interaction between PTH and both klotho and calcidiol levels.

Parathormone is an independent predictor of cardiovascular events in coronary patients, adding complimentary prognostic information to NT-proBNP plasma levels. This predictive value is restricted to patients with high FGF23 plasma levels. This should be considered in the design of future studies in this field.