procalcitonin ( pct ) is a 14-kd protein encoded by the calc-1 gene and synthesized physiologically by thyroid c - cells . under normal conditions , serum pct levels are negligible .
after shock or tissue injury ( i.e. burn , trauma , surgery ) or infections and sepsis , pct mrna expression has been documented in human extra - thyroidal tissues .
thus , systemic pct concentrations are considered as a component of the inflammatory response and as an acute - phase marker . in cardiac acute patients , data on pct
some studies [ 3 , 4 ] reported that pct levels were increased in acs patients on admission , whereas other investigations [ 5 , 6 ] documented that plasma pct concentrations were in the normal range in patients with uncomplicated acute myocardial infarction .
elevated concentrations of pct have been reported in patients with cardiogenic shock . in a more recent retrospective study , it was observed that cs patients showed high pct concentrations , especially in the presence of multiorgan failure ( mof ) and in absence of signs of infections ( cultures and clinical findings ) .
we recently   observed that the degree of myocardial ischemia ( clinically indicated by the whole spectrum of acs , from unstable angina to cardiogenic shock st - elevation following myocardial infarction ) and the related inflammatory - induced response are better reflected by crp ( which was positive in most acute cardiac care patients of all our subgroups ) than by pct which seems more sensible to a higher extent of inflammatory activation , being positive only in all cs patients . in these patients , the clinical interpretation of absolute pct values ( both in diagnostic and prognostic terms ) , represent a major challenge since they may be influenced by several factors , such as the degree of systemic inflammatory response , the coexistence of multiorgan dysfunction , the presence / absence of infections and finally by the time of measurements during hospital course ( i.e. the dynamics of pct levels ) .
no data are so far available on the dynamics of pct levels in patients with cardiogenic shock .
the aim of this preliminary investigation was therefore to evaluate the serum evolution of pct during intensive cardiac care unit ( iccu ) staying in a group of patients with cardiogenic shock ( cs ) following st - elevation myocardial infarction ( stemi ) submitted to primary percutaneous intervention ( pci ) with no laboratory or clinical sign of infection .
ten consecutive patients with cardiogenic shock following stemi were submitted to pci and then admitted to our 12-bed iccu in florence , a tertiary center , from 1 september 2008 to 31th march 2009 . to be eligible for the present study , all patients had to be free of infection at the time of blood sampling , as evidenced by both clinical and microbiological examinations , including urinary cultures and microbiological examinations of tracheal aspirate in mechanical ventilated patients and blood cultures . a clinical diagnosis of cardiogenic shock was made if all the following criteria were present : 1 .
systolic blood pressure persistently less than 90 mmhg or vasopressors required to maintain a systolic blood pressure of more than 90 mmhg ; 2 .
signs of hypoperfusion ( e.g. urine output less than 30 ml / hour or cold / diaphoretic extremities or altered mental status ) ; 3 .
clinical evidence of elevated left ventricular filling pressure ( e.g. pulmonary congestion on physical examination or chest x - ray ) .
pulmonary artery catheterization was not required when all clinical criteria and echocardiographic evidence of left ventricular dysfunction without mechanical complications were present .
the day after iccu admission blood samples were obtained for cardiac biomarkers ( tni < 0.15 ng / ml ) , leucocytes count ( 4000 - 10000/l ) , crp ( < 9 mg / dl ) , uric acid ( < 6.5 mg / dl ) , nt - pro brain natriuretic peptide ( nt - probnp , in males 0 - 50 yrs : < 88 pg / ml , > 50 yrs : < 227 pg / ml ; in females : 0 -50 yrs : < 153 pg / ml ; > 50 yrs : < 334 pg / ml )   and procalcitonin measurements ( normal values < 0.5 ng / ml ) .
transthoracic 2-dimensional echocardiography was performed on admission in order to evaluate left ventricular ejection fraction ( lvef ) .
apache ii ( acute physiology and chronic health evaluation ii ) score was also assessed .
the study design was approved by the local ethic committee and inform written consent was obtained for each patient .
statistical analysis was performed by means of spss 13.0 package ( spss inc , chicago , il ) .
data are reported as frequencies and percentages or means  s.d . and analyzed with fisher s exact test and student s t test , respectively .
since pct was determined once a day , its mean value for each day of hospital stay in either group of patients has been calculated and graphically plotted in order to obtain two linear regression lines , whose slopes have been subsequently compared by means of an f test .   in all analyses ,
table 1 shows the clinical characteristics of cs patients following stemi included in the study after pci .
clinical characteristics of patients included in the study . compared with survivors , dead patients exhibited higher values of apache ii score , as well as trend towards higher serum concentrations of troponin i , though it did not reach statistical significance .
no significant differences were detectable in regard to age , sex , infarct location , left ventricular ejection fraction , and mean arterial pressure between the two subgroups .  
as depicted in table 2 , higher values of glycemia , nt - probnp and crp were detectable in dead patients in respect to survivors .
basal serum concentrations of procalcitonin were higher in ( dead ) survivors patients , though this difference did not reach statistical significance due to high values of standard deviation .
as depicted in figure 1 , the pattern of pct variations during iccu course was significantly different in cs patients who survived in respect to those who died ( survivors : slope = -3.760.71 standard error ; dead : slope = -0.810.35 standard error , p=0.004 ) .
the main finding of the present investigation , though preliminary and performed in a small subset of patients , is that the patterns of temporal pct variations throughout iccu course were heterogeneous in patients with cs and no clinical or laboratory signs of infection .
a progressive reduction in pct values was observed in cs patients who survived , whereas the lack of changes in pct concentrations was documented in cs patients who died .
conversely , basal absolute pct values were not significantly different between the two subgroups , since they exhibit a wide range of values in the overall population .
sponholz et al .   described the evolution of serum procalcitonin levels after uncomplicated cardiac surgery and observed a progressive return to normal levels within the first week .
peak pct levels were reached within 24 hours postoperatively and this increase seemed to be dependent on the surgical procedure , being more invasive procedures associated with higher pct levels , and on intraoperative events , including aortic cross - clamping time , duration of cardiopulmonary bypass and duration of surgery . in infected patients , pct levels were elevated throughout the first week postoperatively [ 19 , 20 , 21 ] , with a more pronounced trend in bacterial and fungal infections than in viral infections of sirs . [ 22 , 23 ] .
the authors concluded that the dynamics of pct levels , rather than absolute values , may be more important for identifying patients with infectious complications after cardiac surgery .
more recently prat et al .   confirmed a slight increase in pct values in the first postoperative day after cardiac surgery , in agreement with previous results [ 25 , 26 , 27 ] and with adamik et al .
, who showed that the development of postoperative complications after cardiac surgery with cardiopulmonary bypass was associated with increased postoperative neopterin and pct levels .
similarly , after heart transplantation , serum pct levels display a rise in response to surgery , with a peak on day two , whereas high peak levels with delayed return to normal values should lead to a search for inflammatory processes , as they are often associated with increased morbidity and mortality .  
likewise , in patients with cardiogenic shock and no sign of infections we documented a reduction of pct levels only in survivors cs patients .
this time course of procalcitonin can probably be explained , both in postsurgical and in cs patients , by normal pct kinetic . in healthy subjects
the injection of endotoxin is followed by a rise in pct , reaching a maximum 24 hours thereafter .  
the return of pct levels to normality within a few days in surgical patients ( after an uncomplicated postoperative course ) and in cs survivors patients can be explained by half - life of pct ( 18 to 24 hours ) , in absence of a further insult that might induce pct production .
our findings , along with those in cardiac surgery   strongly support the contention that the  dynamic 
approach   may be more reliable that the static one ( that is the absolute single pct value ) especially in the challenging conditions characterized by a systemic inflammatory response , such as cardiac surgery and cardiogenic shock . indeed , in a cohort of unselected critically ill patients , jensen et al .  
observed that a pct increase was an independent predictor of 90-day survival and that the pct day - by - day changes was able to identify critically ill patients at a higher risk of icu mortality . on the other hand ,
the initial  ct level did not predict mortality , even though many patients were admitted with a pct 1.0 ng / ml .
this suggests that several pct measurements should be made consecutively to assess the critically ill patient s infection - related mortality risk ( to monitor treatment of infection day - by - day ) . in our investigation
we further confirmed that higher values of nt - probnp are associated with increased mortality in cs patients   and that a more marked systemic inflammation ( as inferred by higher values of crp ) and higher severity score ( as indicated by apache ii ) were associated with an ominous prognosis .
the main limitation of the present investigation is represented by the small number of patients . however , the population is homogeneous , comprising patients with cardiogenic shock following stemi all submitted to pci , with no clinical and laboratory sign of infections .
it is interesting to note that , despite the small number of subjects , the behavior of pct was clearly detectable .
according to our preliminary findings , patterns of temporal pct variations throughout iccu course were heterogeneous in patients with cs following stemi submitted to pci and no clinical or laboratory signs of infection .
a progressive reduction in pct values was observed in cs patients who survived , whereas a lack of changes in pct concentrations was documented in cs patients who died .
our findings strongly support the contention that the  dynamic  approach may be more reliable that the static one ( that is the absolute single pct value ) especially in the challenging conditions characterized by a systemic inflammatory response , such as cardiogenic shock .
we further confirmed that higher values of nt - probnp are associated with increased mortality in cs patients and that a more marked systemic inflammation ( as inferred by higher values of crp ) and higher severity score ( as indicated by apache ii ) were associated with an ominous prognosis .
 introductionprocalcitonin concentrations are considered as a component of the inflammatory response and as an acute - phase marker , after shock or tissue injury ( i.e. burn , trauma , surgery ) or infections and sepsis . 
 no data are so far available on the dynamics of procalcitonin levels in patients with cardiogenic shock following st - elevation myocardial infarction , with no clinical or laboratory sign of infection.methodswe evaluated procalcitonin values every day during intensive cardiac care staying in ten cardiogenic shock patients admitted to our intensive cardiac care unit . nt - pro brain natriuretic peptide , c reactive protein and apache ii score were also assessed.resultssix patients survived , whereas 4 patients died . 
 a progressive reduction in procalcitonin values was observed in cardiogenic shock patients who survived , whereas the lack of changes in procalcitonin concentrations was documented in cardiogenic shock patients who died ( survivors : slope = -3.76 ; dead : slope = -0.81 , p=0.004 ) . 
 furthermore , higher values of glycemia , nt - pro brain natriuretic peptide and c reactive protein ( as well as higher apache ii scores ) were detectable in dead patients in respect to survivors.conclusionsin our preliminary study we observed that in patients with cardiogenic shock and no sign of infections a reduction of procalcitonin levels was detectable only in survivors . moreover , higher values of nt- brain natriuretic peptide , a marked systemic inflammation ( higher values of c reactive protein ) and higher severity score ( as depicted by apache ii ) are associated with an ominous prognosis in cardiogenic shock patients . 