Can available mathematical models predict serum digoxin levels in Thai patients?

WHAT IS KNOWN AND OBJECTIVE

Digoxin is commonly prescribed for heart failure patients with reduced ejection fraction (HFrEF) and patients with atrial fibrillation (AF). Due to digoxin's narrow therapeutic range, monitoring the serum digoxin concentration (SDC) is important. However, the SDC measurement is not widely available. Equations using clinical parameters can be employed to estimate the SDC but have never been studied in the Thai population. Therefore, we conducted this study to evaluate the correlation between the measured SDC and predicted digoxin level using 2 commonly used equations: the Konishi equation and the Koup and Jusko equation.

METHODS

This report describes prospective, cross-sectional study conducted at Chiang Mai University. One hundred and fourteen patients were recruited in the study. All of the patients were diagnosed as having HFrEF, AF or both and had been receiving digoxin for at least 4 weeks. The SDC of each patient was measured at steady state and assigned to one of 3 groups according to the classifications of the Digitalis Investigation Group (DIG) trial: in the therapeutic range, over the therapeutic range and in the suboptimal range.

RESULTS AND DISCUSSION

There were significant correlations between the measured and predicted SDCs using both the Konishi equation and the Koup and Jusko equation, which had correlation coefficients (R) of 0.69 and 0.31 (P < .05 for both), respectively. The percentages of patients with measured SDCs in the therapeutic range, over the therapeutic range and in the suboptimal range were 27.2%, 9.6% and 63.2%, respectively. The sensitivity and specificity of the Konishi equation in predicting SDCs in the over the therapeutic range were 72.73% (95% Confidence interval (CI): 39.03%-93.98%) and 80.58% (95% CI: 71.62%-87.72%), respectively. Of the 5 patients (4.4%) who were rehospitalized, 2 patients (0.01%) were readmitted due to acute decompensated heart failure (ADHF). One of the patients had an SDC that was over the therapeutic range. None of the readmitted patients had ventricular arrhythmia.

WHAT IS NEW AND CONCLUSIONS

The Konishi equation yielded better predictions of the SDC, especially in the subgroup of HFrEF patients. Furthermore, the prediction of SDCs in the over the therapeutic range using this equation was superior to that of the Koup and Jusko equation. With further validation in a larger population, this equation should facilitate the detection of patients who are over the therapeutic range in clinical practice.

Splenectomy: a strong risk factor for pulmonary hypertension in patients with thalassaemia

OBJECTIVE

To determine the association between splenectomy and pulmonary hypertension in patients with thalassaemia with anaemia.

DESIGN

Prospective cross-sectional study.

METHODS

68 patients with thalassaemia, who had a haemoglobin concentration of less than 100 g/l, were recruited into this study. Echocardiography was performed before clinical data were reviewed. Pulmonary artery pressure was estimated by measuring the systolic transtricuspid pressure gradient from tricuspid regurgitation and adding it to the right atrial pressure, which was estimated by the response of the inferior vena cava to inspiration. Pulmonary hypertension was defined as systolic pulmonary artery pressure > 35 mm Hg. History of splenectomy and other clinical data were compared between patients with and without pulmonary hypertension.

RESULTS

29 patients had pulmonary hypertension and 39 did not. Patients with pulmonary hypertension had significantly more nucleated red blood cells and higher platelet counts, and a higher prevalence of splenectomy (75.8% v 25.6%, odds ratio 9.1, 95% confidence interval 3.0 to 27.7). In multivariate analysis, splenectomy was the only factor significantly related to pulmonary hypertension.

CONCLUSION

Splenectomy is a strong risk factor for pulmonary hypertension in patients with thalassaemia.

Acute aortic valvulitis as an initial presentation of systemic lupus erythematosus

Valvular involvement in patients with systemic lupus erythematosus (SLE) is not uncommon but patients rarely present with it. The mitral valve is most commonly involved. We report a 36-year-old man who had an episode of acute fever, arthritis, and acute aortic insufficiency with a small vegetation at the tip of the aortic valve mimicking infective endocarditis, proven later to be due to SLE. SLE should be considered as one of the uncommon causes of acute aortic insufficiency.