Myocardial injury and heart failure biomarkers in acute intermittent porphyria

Abstract Background Acute intermittent porphyria (AIP) is a rare metabolic disorder caused by the defect in the hydroxymethylbilane synthase gene, encoding the third enzyme in heme biosynthesis pathway. The main symptoms include abdominal pain, vomiting, paralysis, confusion. Exacerbation of AIP may manifest with elevation of blood pressure and tachycardia due to hyperactivity of sympathetic nervous system. Data regarding cardiac function in AIP are scarce. Purpose The aim of this study was to assess the myocardial injury and heart failure biomarkers during AIP exacerbations and remission. Methods This cohort prospective study encompassed patients at the age 18-65 years who had at least one exacerbation of AIP in their lifetime. Patients examined during the AIP exacerbations were reassessed in the remission phase. The concentrations of sodium, troponin T, CK-MB mass, N-terminal pro-B-type natriuretic peptide (NT-proBNP) and metoxycatecholamines in blood were assessed. Blood pressure was measured with 24-hour ABPM. Echocardiography was performed according to the current recommendations. Results The total number of 70 patients with AIP were enrolled to the study (April 2019 - March 2023). We assessed 36 patients in both phases of disease, mean age 37 years (21-63), 75% females. The median of prior AIP exacerbations was 8. During the exacerbations a significant increase in the concentrations of NT-proBNP (250 [97 ; 501] vs. 89 [48 ; 140] pg/mL, p<0.001), metanephrine (49.0 [37.8 ; 61.2] vs. 41.4 [36.8 ; 53.3] pg/mL, p=0.009) and normetanephrine (169.8 [118.2 ; 327.2] vs. 93.2 [78.1 ; 120.9] pg/mL, p<0.001) was observed. Conversely, sodium concentrations decreased (136 [133 ; 140] vs. 140 [139 ; 142] mmol/L, p<0.001). There were no significant differences in the values of troponin (5.4 [4.0 ; 11.3] vs. 5.6 [3.7 ; 9.5] ng/L, p=0.445), CK-MB mass (1.88 [0.84 ; 2.64] vs. 1.21 [0.83 ; 2.80] ng/mL, p=0.80). In the acute phases of AIP the levels of NT-proBNP were correlated negatively with the values of sodium concentrations (r=-0.36, p=0.032) and positively with average systolic blood pressure (r=0.32, p=0.06). Echocardiography showed an increase in left ventricular (LV) mass indices in some patients hospitalized due to AIP symptoms. Sodium concentrations correlated negatively with these changes (r=-0.36, p=0.032). LV ejection fraction was slightly higher during AIP exacerbations. There were no significant differences in other parameters of LV systolic and diastolic function. Conclusions During acute intermittent porphyria (AIP) exacerbations there is an increase in the concentrations of NT-proBNP and catecholamines in blood. In most patients the levels of markers of myocardial injury, such as troponin and CK-MB mass, do not differ significantly between phases of disease. During AIP exacerbations some patients experience an increase in LV mass which may be associated with hyponatremia. In most cases cardiac function do not change significantly.Frequency of abnormal laboratory resultsResults of echocardiography