Arterial and venous thromboembolic complication risks in patients with myeloproliferative neoplasms

Arterial and venous thromboembolic (ATE/VTE) complications are more commonly observed in patients with myeloproliferative neoplasms (MPN) than in the general population and are associated with an increased risk of both mortality and morbidity. A study by Wille et al.¹ examined the risk and incidence of ATE and VTE in patients with different MPN subtypes. The MPN Hub is pleased to summarize these findings here.

Study design¹

This single-center retrospective study evaluated 832 patients with MPN for ATE/VTE complications.

ATE and VTE were shown to be associated with MPN if they occurred within two years before or following an MPN diagnosis.

Patient characteristics

At a median follow-up of 6.6 years, 180 patients experienced an ATE/VTE, with a 36.2% probability of a thromboembolic complication. The patient characteristics of the total cohort and those with a first complication are outlined in Table 1 and Table 2.

Table 1. Total cohort patient characteristics*

Characteristic, %	Total cohort N = 832
Male	39.1
Female	60.9
MPN diagnosis
Essential thrombocytosis	31.7
Polycythemia vera	34.1
Myelofibrosis	31.1
Driver mutations
JAK2	69.8
CALR	14.4
MPL	2.5
Triple negative	5.2
Incomplete	8.1
ATE, arterial thromboembolism; CALR, calreticulin; JAK2, Janus kinase 2; MPL, myeloproliferative leukemia; MPN, myeloproliferative neoplasm; VTE, venous thromboembolism. *Adapted from Wille, et al.1

Table 2. Patient characteristics if patients with a first complication*

Characteristic, %	Patients with thromboembolic complications N = 180
Time of complication
Prior to MPN diagnosis	32.2
At the time of MPN diagnosis	17.2
After MPN diagnosis	50.6
VTE	58.3
ATE	41.6
ATE, arterial thromboembolism; MPN, myeloproliferative neoplasm; VTE, venous thromboembolism. *Adapted from Wille, et al.1

Results¹

• The incidence of VTE was higher than ATE, with 58.3% vs 41.6% of patients experiencing a thromboembolic complication, respectively.
• The most common localizations of ATE were stroke, followed by transient ischemic attacks (Figure 1A).
• The most common localization of VTE was deep vein thrombosis with or without pulmonary embolism, followed by splanchnic vein thrombosis (Figure 1B).

Figure 1. Localization and incidence of A ATE and B VTE*

ATE, arterial thromboembolism; DVT, deep vein thrombosis; PE, pulmonary embolism; TIA, transient ischemic attack; VT, vein thrombosis; VTE, venous thromboembolism.
*Data from Wille, et al.¹

The cumulative incidence of ATE and VTE was comparable in the first year of follow-up. However, VTE became more common over time; at 20 years, the incidence of ATE and VTE was 0.122 and 0.18, respectively (Figure 2).

Figure 2. Cumulative incidence for ATE and VTE over time* 

ATE, arterial thromboembolism; CI, confidence interval; VTE, vein thromboembolism.
*Data from Wille, et al.¹

When comparing factors associated with an increased risk of thromboembolic complications, differences were identified in both MPN subtype and mutational status (Figure 3).

• A CALR and incomplete mutational status were associated with a significantly decreased risk compared with JAK2 mutation.
• The polycythemia vera subtype was associated with a significantly increased risk compared with other MPN subtypes.

Figure 3. Risk factors associated with an increased risk of thromboembolic complications*^†‡§ 

CALR, calreticulin; CI, confidence interval; MPL, myeloproliferative leukemia; MPN, myeloproliferative neoplasm.
*Data from Wille, et al.^1
†Values in bold are statistically significant.
^‡Mutational status are compared with JAK2 mutation.
^§Polycythemia vera is compared with other MPN subtypes.

Conclusion

MPN are associated with a generally increased risk of VTE and ATE compared to a healthy population, with polycythemia vera posing the highest risk. Mutational status also influenced complications, and patients with CALR and incomplete mutational status were at a significantly decreased risk compared with other mutations, particularly the JAK2 mutated group.