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Transcatheter therapy for infants and children with severe bilateral peripheral pulmonary artery stenosis has become safer over the past decades, according to results of a single-center series published online August 13, 2013, ahead of print in Circulation: Cardiovascular Interventions. Although reintervention is common, hemodynamics improve substantially over time, with most patients asymptomatic at late follow-up. 

Investigators led by Audrey C. Marshall, MD, of Children’s Hospital (Boston, MA), analyzed the outcomes of 69 children with isolated severe bilateral peripheral pulmonary artery stenosis who underwent transcatheter intervention at their institution between July 1984 and July 2009. Patients received stenting or standard, high-pressure, or cutting-balloon angioplasty at operator discretion. Median age at intervention was 16 months; 81% were under 3 years of age and none were older than 5 years. 

More than half of the cohort (55.7%) had genetic or syndromic diagnoses, including Williams syndrome (n = 23), non-Williams familial arteriopathy (n = 13), and Alagille syndrome (n = 3). 

Acute Improvement in Pressure Ratio

Median ratio of right ventricular (RV)-to-aortic pressure decreased from 1.00 before intervention to 0.88 afterward (pairwise median decrease of 0.18; P <0.001). The ratio declined by at least 0.3 in 31% of patients and either increased or decreased by at least 0.1 in 38%. Higher RV:aortic pressure ratio before intervention was associated with a greater decrease after intervention (P < 0.001). Syndromic diagnosis, stent implantation, age at intervention, and number of vessels dilated did not influence the magnitude of change in the ratio.

There were 4 deaths from complications during the initial catheterization, although the most recent death occurred in 1997. Three of the deaths occurred after hemodynamic instability during catheterization in patients with concomitant supravalvar aortic stenosis.

Reintervention Common But Effective

At a median follow-up of 8.5 years, 10 patients were known to have died. Overall survival was 88 ± 4% at 1 year after the initial intervention and 87 ± 4% at 10 years. Patients with lower initial RV:aortic pressure ratio tended to survive longer. There was no association between survival and age at first intervention, genetic/syndrome diagnosis, or supravalvar aortic stenosis.

Freedom from transcatheter reintervention was 47 ± 7% at 1 year after the first intervention and 24 ± 6% at 5 years. Higher RV:aortic pressure ratio at the end of the first catheterization was linked to shorter freedom from reintervention (HR 1.18 per 0.1 increase in ratio; P = 0.01).

At least 1 transcatheter reintervention was performed in 26% of patients, and 35% underwent 2 or more interventions. In addition, 13 patients (19%) underwent surgical pulmonary artery intervention, including 10 cases of augmentation aortoplasty for supravalvar aortic stenosis. Freedom from death or any pulmonary artery reintervention was 33 ± 6% at1 year and 19.5% at 5 years.

On univariate analysis, factors associated with higher risk of reintervention or death were:

• Age < 1 year at the first catheterization (HR 1.9; P = 0.02)
• Higher preintervention RV:aortic pressure ratio (HR 1.1 per increase of 0.10 in RV:aortic pressure ratio; P = 0.02)

Improved Hemodynamics and Clinical Status

Among the 41 surviving patients who had a diagnostic or interventional catheterization at least 1 year after the index catheterization, median RV:aortic pressure ratio had decreased from 1.0 at the initial catheterization to 0.53 at the most recent catheterization (median pairwise decrease 0.34; P < 0.001) over a median duration of 5.1 years.

When the most recent RV:aortic pressure ratio by echocardiogram was included for those without a second catheterization or who had an echocardiogram more than 1 year after the most recent catheterization (n = 45), 56% had a ratio of less than 0.5. Moreover, among the 49 patients with sufficient follow-up data to determine New York Heart Association class, 82% were class I and 16% were class II.

The authors observe that “[m]ortality was concentrated early in our experience and in the acute period because of complications surrounding [pulmonary artery] interventions and other cardiac procedures. Reinterventions on the branch [pulmonary arteries] were common, but RV:aortic pressure ratios were significantly lower at follow-up than before intervention, and no patients are known to have died from long-term progressive RV cardiac failure.”

Innovations Have Diminished Early Risk

With current techniques, periprocedural mortality is considerably lower, Ziyad M. Hijazi, MD, MPH, of Rush University Medical Center (Chicago, IL), told TCTMD in a telephone interview. Of the patients who died early in the study, some probably had genetic syndromes and bilateral obstruction, he noted, and intervention was fatal. “What the investigators later initiated—and today most operators also do—is create an atrial septal defect before intervention,” he said. “That way, you maintain cardiac output, and these patients do relatively well.”

In addition, the recent advent of cutting balloons has contributed to better angiographic results, Dr. Hijazi said, noting that the researchers had access to this technology only at the end of the study period.

The authors observe that despite the hemodynamic improvements achieved by intervention in most patients over time, many still had modestly elevated RV pressure, and it is unclear whether this chronic overload always leads to dilated ventricles and cardiac failure. “Further study of this issue, and longer follow-up of this cohort of patients, may help determine how aggressively to pursue RV pressure relief in patients with [peripheral pulmonary stenosis],” they write.

But Dr. Hijazi cautioned, “We should not convey the message that these patients will get better on their own and don’t need intervention. You have to open up these vessels before age 6 to allow normal lung development. If you wait until later, lung development will cease and then even if you open up the vessels, it may not be of great benefit.”

Overall, these pediatric patients remain a challenging group, with multiple comorbidities and high periprocedural risk, Dr. Hijazi commented. Nonetheless, he added, “this paper confirms that aggressive balloon angioplasty can work, and the long-term outcomes are not bad at all.”

 

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Source:
Cunningham JW, McElhinney DB, Gauvreau K, et al. Outcomes after primary transcatheter therapy in infants and young children with severe bilateral peripheral pulmonary artery stenosis. Circ Cardiovasc Interv. 2013;Epub ahead of print.

 

 

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