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CompletedNCT00438113SMAC AFUpdated Jun 20, 2017

Atrial Substrate Modification With Aggressive Blood Pressure Lowering to Prevent AF

A Phase 4 interventional study of Aggressive Blood Pressure control in Atrial Fibrillation, sponsored by Nova Scotia Health Authority. Completed at 1 site in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2017-06-20.

Sponsored by Nova Scotia Health Authority · Phase 4, Interventional, and Prevention

Phase
Phase 4
Study type
Interventional
Enrollment
184
Allocation
Randomized
Ages
18 Years and older
Sex
All
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Study summary

Atrial fibrillation (AF) is a very common arrhythmia causing many symptoms resulting in numerous hospitalizations. Catheter ablation is a technique that has evolved significantly to improve symptomatic recurrences, but does not offer a 100% cure rate. We hypothesize that the use of aggressive BP lowering will reduce the rate of recurrent AF after catheter ablation for AF. We plan a randomized clinical trial of aggressive BP lowering versus standard BP control to investigate this.

Read the detailed description

Background: Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with significant morbidity, necessitating treatment. Radiofrequency ablation for atrial fibrillation/flutter has evolved significantly and is the closest we have come to a 'cure' for these dysrhythmias. Recurrence of atrial fibrillation in those who have undergone radiofrequency ablation as treatment AF is up to 40% at one year and higher in those with persistent AF. Hypertension is a potent risk factor for AF, but recent studies have demonstrated that even modest increases in BP may lead to a higher incidence of AF. There is no clinical trial evidence to date that has investigated aggressive BP control in patients post radiofrequency ablation for AF to prevent recurrent AF.

Objective: We propose to determine if aggressive BP control reduces recurrent AF post ablation.

Hypothesis: Aggressive BP lowering will reduce the incidence of recurrent AF post ablation.

Research Plan:

Study Design. This will be a randomized open label trial in patients who are post catheter ablation for atrial fibrillation. Randomization to either aggressive BP lowering or standard BP control will occur three to six months prior to the procedure.

Study Population. Patients will be included if they have persistent or high burden paroxysmal (refractory to class 1 or 3 antiarrhythmic medication) and intend to have a catheter ablation procedure for AF.

Followup. Patients will be followed at 3 month intervals for the first year, then every 6 months to a maximum of 30 months or the common study end date has been reached (1 year post randomization for the last patient enrolled).

Statistical Analysis. Kaplan-Meier analysis of the primary outcome will be performed. A Cox proportional hazards model will be constructed to assess the effect of variables chosen a priori on the primary outcome.

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Conditions studied

  • Atrial Fibrillation

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Keywords

  • blood pressure
  • atrial fibrillation
  • catheter ablation
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In context

Atrial Fibrillation

3,870 studies on the registry are indexed under Atrial Fibrillation; 924 are open to participants now.

This study's enrollment of 184 is above the median of 144 across 2,380 interventional studies indexed under Atrial Fibrillation.

Browse Atrial Fibrillation studies →

Lead sponsor

Nova Scotia Health Authority is the lead sponsor of 255 studies on the registry; 76 are open to participants now.

Counted across the registry records on this site, refreshed daily.

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Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

  • Documented systolic blood pressure greater than or equal to 130 mmHg
  • Undergoing planned catheter ablation for persistent AF (lasting > 7 days and \< 365 days or requiring electrical or chemical cardioversion) OR High burden paroxysmal AF > 6 months (greater than or equal to 3 symptomatic episdes in past 6 months and refractory or inteolerant to at least 1 class 1 or 3 antiarrhythmic)

Exclusion criteria

Exclusion Criteria:

  • Permanent atrial fibrillation
  • Contraindication to Accupril or any other ACE-I
  • Women of child-bearing potential
  • Life expectancy less than 1 year
  • Less than 18 years of age
  • Unable to give informed consent
  • Known moderate to several renal dysfunction (eGFR \< 30 ml/min/1.73m2)
  • Prior AF catheter ablation
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Study design

Phase
Phase 4
Primary purpose
Prevention
Allocation
Randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
184 participants (actual)

Study arms

  • Active comparator
    Aggressive Blood Pressure control

    The experimental arm will receive open label therapy to achieve a target systolic blood pressure less than or equal to 120 mmHg. If the average BP is found to be \> 120 mmHg at the baseline, telephone or clinic followup visits, treatment will be recommended based on the following regimen (For details, please see Appendix 4): Step 1 - Accupril, titrated to maximum tolerated dose, beginning at 20 mg po od followed by 40 mg successively Step 2 - combination of Accupril with Hydrochlorothiazide 12.5 mg po od. Step 3 - Addition of Atenolol 50 mg po od. Step 4 - Addition of Norvasc 2.5-10 mg po od. Step 5 - Addition of Terazosin 1 mg po od.

    Drug: Aggressive Blood Pressure control

  • No intervention
    Standard Blood Pressure control

    Treatment will be carried out as per the CHEP guidelines. These patients may require ACEi or ARBs for their treatment. No changes to their drug regimen will be made as long as BP measurements are congruent with current guidelines. These modifications will be made as per standard practice by the physician who is primarily involved with their care (this may be a family physician or a specialist, depending on the patient). Patients with diabetes in the standard arm will be treated to a target BP of \<130/80 as per the CHEP guidelines.

Interventions

  • DrugAggressive Blood Pressure control

    Aggressive Blood Pressure therapy, alone or combination therapy, to reach a target BP equal to or less than 120/80 mmHg

    Also known as: Accupril, Atenolol, Norvasc, Terazosin, Hydrochlorothiazide

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What researchers measure

Primary outcomes

  1. Time to symptomatic AF/atrial tachycardia (AT)/atrial flutter (AFl) lasting > 30 seconds more than 3 months post ablation.

    This has been altered since the inception of the study to include atrial tachycardia and atrial flutter, as there have been changes to how ablation is performed since the study began. Specifically, the STAR AF2 study found that PVI is similar to PVI in addition to either complex fractionated electrogram ablation or PVI in addition to linear ablation. Given this, the occurrence of AT/AFL was thought to be iatrogenic and occur as a consequence of various ablation strategies, rather than to the substrate, hence was excluded from the primary endpoint. Given the change in strategy of ablation, the inclusion of AT/AFl in the primary outcome is now necessary as it may reflect change in substrate, rather than ablation strategy, as previously thought. In addition, from a patient perspective, the occurence of AT/AFl is indistinguishable from a symptoms point of view.

    Time frame: at least 3 months post catheter ablation

Secondary outcomes

  1. Any recurrent atrial fibrillation/atrial tachycardia/atrial flutter post randomization

    Time frame: up to 30 months post randomization

  2. Recurrent atrial fibrillation/atrial tachycardia/atrial flutter (symptomatic or asymptomatic) post ablation

    Time frame: up to 30 months post randomization

  3. atrial fibrillation/atrial tachycardia/atrial flutter burden (pre and post ablation)

    Time frame: up to 30 months post randomization

  4. Generic and disease specific quality of life

    Time frame: 12 months

  5. Correlation of BNP and CRP and recurrence of atrial fibrillation/atrial tachycardia/atrial flutter

    Time frame: 12 months

  6. Recurrent AF ablation therapy

    Time frame: up to 30 months post randomization

  7. Visits to the ER or hospitalization for atrial arrhythmia

    Time frame: up to 30 months post randomization

  8. Thromboembolic events

    Time frame: up to 30 months post randomization

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Study locations

1 site
  • QE II Health Sciences Centre
    Halifax, Nova Scotia B3H 3A7, Canada
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References and documents

Publications

  • Weng W, Choudhury R, Sapp J, Tang A, Healey JS, Nault I, Rivard L, Greiss I, Bernick J, Parkash R. The role of brain natriuretic peptide in atrial fibrillation: a substudy of the Substrate Modification with Aggressive Blood Pressure Control for Atrial Fibrillation (SMAC-AF) trial. BMC Cardiovasc Disord. 2021 Sep 16;21(1):445. doi: 10.1186/s12872-021-02254-5. PubMed 34530738 ↗
  • Parkash R, Wells GA, Sapp JL, Healey JS, Tardif JC, Greiss I, Rivard L, Roux JF, Gula L, Nault I, Novak P, Birnie D, Ha A, Wilton SB, Mangat I, Gray C, Gardner M, Tang ASL. Effect of Aggressive Blood Pressure Control on the Recurrence of Atrial Fibrillation After Catheter Ablation: A Randomized, Open-Label Clinical Trial (SMAC-AF [Substrate Modification With Aggressive Blood Pressure Control]). Circulation. 2017 May 9;135(19):1788-1798. doi: 10.1161/CIRCULATIONAHA.116.026230. Epub 2017 Feb 22. PubMed 28228428 ↗

Individual participant data

Plan to share: No

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Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Jun 20, 2017, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
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Registry details

Key details

Study ID
NCT00438113
Lead sponsor
Nova Scotia Health Authority
Collaborators
Nova Scotia Health Research Foundation
Responsible party
Ratika Parkash (Staff Cardiologist, Electrophysiology, Nova Scotia Health Authority) — Principal investigator
First posted
Feb 21, 2007
Start date
Dec 2009
Primary completion
Sep 2016
Completion
Sep 2016
Last update
Jun 20, 2017

Study contacts

Ratika Parkash, MD MSc
principal investigator · Dalhousie University/QEII HSC

Oversight

Data monitoring committee
No
View the source record on ClinicalTrials.gov ↗

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This study is completed, as verified in Jun 2017. You cannot join it, but the record below documents what was studied.

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