medwireNews: Reducing target blood pressure (BP) does not decrease the incidence of recurrent arrhythmia among patients undergoing catheter ablation for atrial fibrillation (AF), results of a randomized trial suggest.
In the SMAC-AF (Substrate Modification with Aggressive Blood Pressure Control) trial, patients with AF whose BP was greater than 130/80 mmHg at baseline were assigned to receive either aggressive (target BP<120/80 mmHg) or standard (target BP<140/90 mmHg) antihypertensive treatment prior to catheter ablation.
As reported in Circulation, mean BP was significantly lower after a median 3.5 months of aggressive treatment compared with 3.1 months of standard treatment, at 123.2/76.7 mmHg versus 135.4/80.8 mmHg. Baseline measurements were an average of 142.9/84.9 mmHg and 142.2/84.3 mmHg, respectively.
However, there was no significant difference in the rate of recurrent symptomatic AF, atrial tachycardia, or atrial flutter occurring more than 3 months post-ablation between the aggressive and standard treatment groups, with corresponding rates of 61.4% and 61.2%.
The team observed a higher incidence of hypotension requiring medication adjustment among patients receiving aggressive compared with standard BP therapy, at 26.1% versus 0%, and 2.2% of participants in the aggressive treatment group were hospitalized due to effects of the study treatment, compared with none in the standard treatment group.
In prespecified subgroup analyses, the researchers found that recurrent arrhythmia occurred significantly less frequently with aggressive compared with standard treatment among patients aged 61 years and older, but that this was not true among younger patients (55.6 vs 76.9% and 67.4 vs 47.8%, respectively).
“The significance of this finding is uncertain in the context of the globally neutral result,” say Ratika Parkash (QEII Health Sciences Center and Dalhousie University, Halifax, Nova Scotia, Canada) and study co-authors. However, they note that there was a larger reduction in BP among patients in the older age group compared with younger participants, which “lends credence to this observation.”
Additionally, there was a significant reduction in recurrent arrhythmia with aggressive versus standard treatment in the subgroup of patients with systolic blood pressure of less than 140 mmHg at baseline, but not in those with higher BP.
Therefore, “benefit from aggressive BP treatment may need to begin further upstream, before patients reach the threshold of a high AF symptom burden requiring catheter ablation,” the authors suggest.
And the team concludes: “Determining at which point in the atrial substrate pathway where upstream therapy would [reduce] atrial arrhythmia […] could result in significant benefits to the increasing population of AF patients.”
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