Thrombocytopenia Serves as Marker of Short- and Long-term Mortality after TAVR

Download this article's Factoid (PDF & PPT for Gold Subscribers) 

In patients undergoing transcatheter aortic valve replacement (TAVR), acquired thrombocytopenia is common, occurring in more than one-third of cases, and serves as a strong and significant correlate for both early- and long-term mortality, according to a study published online March 4, 2014, ahead of print in European Heart Journal. The investigators say testing platelet count after TAVR is a simple way to predict clinical outcomes.

Ron Waksman, MD, of MedStarWashington Hospital Center (Washington, DC), and colleagues looked at the incidence and correlates of low platelet count in 488 patients undergoing TAVR at 2 US centers (MedStarWashington Hospital Center and Columbia University Medical Center/NewYork-Presbyterian Hospital) from May 2007 to September 2012.

Patients were categorized as having thrombocytopenia according to nadir platelet count post procedure:

• Severe (50 x 10⁹/L)
• Moderate (50-99 x 10⁹/L)
• No/mild ( ≥100 x 10⁹/L)

Thrombocytopenia Common, Predictive of Poorer Outcome

By a median time of 2 days post-procedure, 36.1% of patients had developed significant thrombocytopenia (30.5% moderate, 5.5% severe). Of these, 81.5% had platelet nadir by the third post-operative day. Upon discharge, the vast majority of patients (90.2%) had no/mild thrombocytopenia.

Degree of platelet nadir after TAVR correlated with both early and late survival. While the group with moderate thrombocytopenia had survival rates similar to those with no/mild thrombocytopenia, patients with severe thrombocytopenia had a higher rate of death within 30 days and poorer long-term survival compared with the other 2 groups (table 1).

Table 1. Early and Late Mortality by Degree of Thrombocytopenia

 
Patients with severe thrombocytopenia also had prolonged ICU stays and higher rates of major vascular complications, life-threatening bleeding, post-procedural sepsis, acute kidney injury (type II/III), and multiple blood transfusions at 30 days compared with the other 2 groups.

However, thrombocytopenia did not affect rates of device success, major stroke, or post-procedure paravalvular leak. Overall, a nadir platelet count of < 50 x 10⁹/L was highly specific (96.3%) and a count of < 150 x 10⁹/L was highly sensitive (91.2%) in predicting risk of death at 30 days (C-statistic 0.76).

Landmark analysis showed that in patients who survived for 1 month after TAVR, those with severe thrombocytopenia had higher 1-year mortality rates (86.8%) than those with lower degrees of thrombocytopenia (85.5% and 64.3% for moderate and mild, respectively; P = 0.039).

Additionally, patients with delayed nadir (≥ 4 days) had worse 1-year survival than those with early nadir (41.3% vs 78.5%; P < 0.001). This group also had more sepsis events and higher acute kidney injury rates, which together translated into higher 30-day mortality rates when compared with those with early nadir. In those with early nadir, the cause of death was mainly cardiovascular (76.9%), while in those with delayed nadir it was mostly non-cardiovascular (90%).

Patients who experienced a decrease in platelet count ≥ 50% had lower survival rates than those with smaller decreases (P < 0.001).

Easily Obtained Marker of Outcome

According to Dr. Waksman and colleagues, thrombocytopenia occurring within 4 days of TAVR “is directly related to procedural/early post-procedural adverse events, such as vascular complication, bleeding, and multiple blood transfusions.” Delayed nadir, meanwhile, is related to the presence of comorbidities such as renal failure, sepsis, and disseminated intravascular coagulation. They further hypothesize that thrombocytopenia after TAVR may indicate the presence of severe physiological stress.

“Rather than being directly implicated in the causal pathway to death, platelet count could be viewed as a ‘final common pathway’ of several death correlates, being an easily obtainable lab result with high predictability, similar to the way in which systemic inflammatory response after TAVR is strongly associated with outcome,” they add.

The investigators recommend evaluating patients for low platelet count and high leucocyte count prior to TAVR and suggest attempting to normalize these results in select cases. After TAVR, platelet counts should be routinely evaluated and nadir count may be used as a marker for patient outcome, they say, adding that the information “may be helpful in managing patient and family expectations.”

Note: Several co-authors of the current paper are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 

---

Source:
Dvir D, Généreux P, Barbash IM, et al. Acquired thrombocytopenia after transcatheter aortic valve replacement: clinical correlates and association with outcomes. Eur Heart J. 2014;Epub ahead of print.

 

 

Related Stories:

• Drop in Platelet Count After TAVR Signals Poor Outcomes
• Post-PCI Platelet Decline Predicts Bleeding, Ischemic Outcomes
• Thrombocytopenia in PCI Patients Signals Higher Complication Risk