Refined Approach to Pulmonary Angioplasty Leads to Better Outcomes

With refinements in imaging and technique, pulmonary artery angioplasty improves both hemodynamics and clinical function in patients with chronic thromboembolic pulmonary hypertension judged unsuitable for endarterectomy. The findings were published online November 27, 2012, ahead of print in Circulation: Cardiovascular Interventions.

Two problems have limited the clinical application of pulmonary angioplasty since its first use in 1998: insufficient efficacy and high risk of complications. To surmount these obstacles, researchers led by Hiromi Matsubara, MD, PhD, of National Hospital Organization Okayama Medical Center (Okayama, Japan), adapted the procedure in several ways, most importantly by using IVUS to optimize balloon sizing.

Dr. Matsubara and colleagues enrolled 68 consecutive patients with chronic thromboembolic pulmonary hypertension between November 2004 and September 2011. All patients were deemed inoperable by surgeons due to factors including the location of thrombi and surgical inaccessibility, age, and comorbidities. Patients showed poor functional status despite receiving warfarin, supplemental oxygen therapy, and more than 1 pulmonary hypertension-targeted drug.

Immediate, Sustained Improvements

Using IVUS and angiographic guidance, angioplasty was performed in a staged fashion. Patients underwent a median of 4 sessions (range, 2-8), with 3 vessels (range, 1-14) dilated per session. Treatment was associated with immediate improvements in clinical and hemodynamic measures (table 1). At baseline, all patients were in World Health Organization (WHO) functional class III or IV, whereas 96% of surviving patients fell into class I or II after angioplasty.

Table 1. Outcomes Within 1 Week of Final Treatment Session

Among 57 patients who underwent right-heart catheterization at 1.0 ± 0.9 years, mean pulmonary arterial pressure stayed level at 24.0 ± 5.8 mm Hg.

Over long-term follow-up (2.2 ± 1.4 years), 1 patient died of pneumonia. The early gains in WHO functional class were maintained. Fewer patients required oral medications (P < 0.05), and more than a third were able to discontinue oxygen therapy.

The main complication was reperfusion pulmonary injury, which occurred in 41 patients (60%). Four cases were severe enough to merit mechanical ventilation, of which 2 also required percutaneous cardiopulmonary support. One of those 2 patients fully recovered but the other died 28 days after angioplasty due to right-sided heart failure. Pulmonary artery perforation occurred in 5 patients, of whom 2 required emergent transcatheter coil embolization.

“This is the first clinical trial to document that refined [balloon pulmonary angioplasty] can be a therapeutic option in inoperable patients with chronic thromboembolic pulmonary hypertension,” the researchers note.

Apart from IVUS and a staged approach, additional refinements included use of a soft-tipped 6-Fr guiding catheter to select the smaller branches of pulmonary arteries with reduced dissection risk as well as use of a thinner wire and low-profile balloon catheter to enable opening of completely obstructed lesions with less risk of perforation. All devices are commercially available.

Taking Aim at Reperfusion Injury

Dr. Matsubara told TCTMD in an e-mail communication that angioplasty for pulmonary hypertension is not widespread, though 200 patients have undergone the procedure in Japan. The work involves collaboration between pulmonary hypertension specialists and interventional cardiologists, he said, adding that, “To my knowledge, Japan leads the field.”

After first concentrating on efficacy, the research team is now “reconsidering our technique to control the incidence and severity of reperfusion injury,” Dr. Matsubara reported. “I believe that we can eliminate [this] life-threatening complication of pulmonary angioplasty in the near future.”

An additional risk of pulmonary angioplasty is radiation exposure, Dr. Matsubara noted.

Randomized trials comparing medical therapy with pulmonary angioplasty would be “ethically problematic” because the latter offers much superior efficacy, he said. “Direct comparison between pulmonary angioplasty and surgical endarterectomy might be considered. However, the technique is still [being refined], and therefore, it is too early to consider the trial.”

Dr. Matsubara stressed that prognosis is poor for inoperable patients unresponsive to medical therapy, most of whom are too old to undergo a lung transplant. “[W]ithout pulmonary angioplasty, most patients would [be] dead,” he said.

Mizoguchi H, Ogawa A, Munemasa M, et al. Refined balloon pulmonary angioplasty for inoperable patients with chronic thromboembolic pulmonary hypertension. Circ Cardiovasc Interv. 2012;Epub ahead of print.

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