Table 2.

Clinical Gaps in Chronic Thromboembolic Pulmonary Hypertension

Topic	Problem	Potential Approach
CTEPD without PH	•Unknown natural history •Unclear treatment risk to benefit ratio	•Prospective registry after acute pulmonary embolism •Multicenter treatment registry
Pulmonary embolism intervention	•Catheter intervention for acute pulmonary embolism when CTEPH already present	•Team with expertise to triage appropriately •Emphasis on hemodynamic assessment over pulmonary pressure •Imaging, machine learning algorithm
Operability	•Accuracy of preoperative prediction of surgical classification or outcome •Degree of small vessel disease and risk for residual PH •Borderline cases	•Comparison between expert MDT prediction vs surgical classification •Use advanced imaging capabilities; machine learning algorithm; discrepancy between burden of disease on imaging and hemodynamics; balloon occlusion technique •Compare strategies for borderline cases: surgery before BPA, BPA before surgery, hybrid PTE and BPA, timing and role of medical therapy
Follow-up after intervention	•Definition of successful PTE •Definition of successful BPA	•Prospective, systematic follow-up of consecutive patients including assessment during exercise after PTE and after BPA
Operable CTEPH	•Definition of expert surgical center •Volume of cases? Mortality rate? Ability to treat segmental or subsegmental disease?	•Surgical CTEPH registry with follow-up beyond hospitalization •Training process •Accreditation process
Inoperable CTEPH	•Definition of patient: imaging, hemodynamics, comorbidities? •Optimal sequence, combination of therapies, or both	•Multicenter treatment registry •Standardized procedural technique •Controlled trials investigating specific strategies •Long-term follow-up

BPA = balloon pulmonary angioplasty; CTEPH = chronic thromboembolic pulmonary hypertension; MDT = multidisciplinary team; PH = pulmonary hypertension; PTE = pulmonary thromboendarterectomy.