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SAN FRANCISCO -- Left atrial appendage (LAA) closure might have a substantial longer-term benefit in reducing hypertension -- or it might not, as dueling studies presented opposite findings from small cohorts.

The findings were presented back-to-back in a session here at the .

In the first, , of the University of Kansas Medical Center in Kansas City, and colleagues reported on 196 consecutive afib patients who got successful epicardial LAA exclusion (143 with Lariat, 30 with Atriclip, and 21 surgically) and found a drop in blood pressure from 142 to 145 mm Hg systolic on average before the procedure to 120 mm Hg at 24 hours, 3 months, and 12 months afterward (P<0.001).

Diastolic pressures also dropped modestly but significantly from an average of 80 mm Hg to 70 to 71 mm Hg at those points in follow-up (P<0.001).

Antihypertensive medication use also declined by an average of 49%, from a mean of 3.2 to 1.9 medications over 12 months.

"The acute hypotensive effects seem to be predominantly related to the diuretic and naturetic effects of ANP degranulation from the necrosing LAA," Lakkireddy suggested.

LAA exclusion "could be a good therapeutic option for patients with atrial fibrillation and drug-resistant hypertension," he concluded, calling for studying this treatment in multidrug-resistant hypertension.

"This is incredibly provocative," said session co-moderator , of Houston Methodist Hospital.

However, in the other study of 30 Lariat-treated patients in a prospective single-center registry of device-assisted LAA closure -- all with a history of hypertension on at least one antihypertensive medication -- , of Vanderbilt University in Nashville, Tenn., and colleagues reported .

The only significant change in blood pressure was a transient decrease from before the procedure to the time of discharge (P=0.003), which Aznaurov chalked up to spot-dosing of IV diuretics to control volume overload during the hospitalization, with no long-term effects out to 24 months of follow-up or changes in blood pressure medication use.

At the least, it was clear that there was no detrimental effect of LAA ligation on blood pressure, he suggested.

While it's true that necrosis of the LAA sets in quickly after the procedure and that this may lead to release of atrial natriuretic peptide (ANP) that lowers blood pressure, compensatory mechanisms provide "plenty of reserve" production of ANP from the right appendage and left atrial bodies, Aznaurov noted.

In Lakkireddy's study, a subgroup of 38 Lariat-treated patients had extensive neurohormonal measurements at baseline through 3 months post-procedure, which suggested downregulation of the renin-angiotensin-aldosterone system.

Although renin showed no upward or downward trend, the following showed downward trends from before to 24 hours after the procedure:

• Adrenaline (95.9 to 54.2, P=0.06)
• Noradrenaline (103.0 to 75.3, P=0.02)
• Aldosterone (4.7 to 2.6, P=0.06)

Those trends were maintained out to 3 months.

But while NTp ANP and NTp BNP rose acutely after the procedure, levels returned to baseline by 3 months, which Lakkireddy agreed was probably evidence of secretory function being taken up by other parts of heart.

Aznaurov countered that "this patient population had systemically held their diuretics on the day of the procedure, so this pre-Lariat blood pressure may simply reflect a worsening of baseline hypertension prior to the procedure -- and that's the data point that we're collecting ... So what we may be seeing in the long term is simply a return to their baseline hypertension control."

"Everybody in this field would have to be extremely cautious about making conclusions for what happens in the hospital, that could be very center-biased depending on your anesthesia, your pain medications, how much fluid you're running through the procedure," noted the other session co-moderator,, of Silicon Valley Cardiology in Palo Alto, Calif.

"The long-term numbers are probably much more important because you could manipulate factors in the hospital levels to make the blood pressure be almost anything you want the next day."