Clinical Evaluation of the Blazer® Open-Irrigated Catheter for Treatment of Type 1 Atrial Flutter (BLOCk-CTI)

• ClinicalTrials.gov Identifier: NCT01253200
• Recruitment Status: Completed
• First Posted: December 3, 2010
• Results First Posted: February 15, 2018
• Last Update Posted: March 19, 2018
• Sponsor: Boston Scientific Corporation
• Information provided by (Responsible Party): Boston Scientific Corporation

• Study Type: Interventional
• Study Design: Allocation: Randomized; Intervention Model: Parallel Assignment; Masking: Single (Participant); Primary Purpose: Treatment
• Condition: Atrial Flutter
• Interventions: Device: Blazer® Open-Irrigated Ablation Catheter; Device: Control Catheter
• Enrollment: 302

Participant Flow

Recruitment Details	Subjects were recruited from referring physicians for ablation for type 1 atrial flutter
Pre-assignment Details	Subjects were excluded if there were no documented episodes of atrial flutter or inclusion criteria were not met. Roll-in subjects were not randomized.

Arm/Group Title	Randomized Blazer® Open-Irrigated Ablation Catheter	Randomized Control Catheter	Roll-in Blazer Open Irrigated Subjects	Roll-in Control Catheter	Not Randomized to Any Treatment Group Subjects
Arm/Group Description	Randomized Patients treated with the Blazer® Open-Irrigated Ablation Catheter Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter	Randomized patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter	The use of the Blazer-Open Irrigated Catheter was required after the second study suspension. Previously enrolled subjects prior to suspension were also classified as Roll-in subjects; not counted in endpoint analysis.	The use of the Control Catheter was optional after the second study suspension in a Roll-in subject. Previously enrolled subjects prior to suspension were also classified as Roll-in subjects; not counted in endpoint analysis.	Five subjects were not Randomized to any treatment group and were not Roll-in subjects.
Period Title: Overall Study
Started	125	125	30	17	5
Procedure	109	111	28	12	0
10 Day Follow-up	106	111	28	12	0
3 Month Follow-up	104	106	28	12	0
Completed	104	106	28	12	0
Not Completed	21	19	2	5	5
Reason Not Completed
Death	1	0	0	0	0
Lost to Follow-up	1	1	0	0	0
Withdrawal by Subject	2	0	0	0	0
Protocol Violation	1	4	0	0	5
intents	10	10	1	3	0
Attempts	6	4	1	2	0

Baseline Characteristics

Arm/Group Title		Randomized Blazer® Open-Irrigated Ablation Catheter	Randomized Control Catheter	Roll-In Blazer® Open-Irrigated Ablation Catheter	Roll-In Control Catheter	Not Randomized to Any Treatment Group	Total
Arm/Group Description		Patients randomized to treatment with the Blazer® Open-Irrigated Ablation Catheter	Patients randomized to treatment with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter	The use of the Blazer-Open Irrigated Catheter was required after the second study suspension. Previously enrolled subjects prior to suspension were also classified as Roll-in subjects; not counted in endpoint analysis.	The use of the Control Catheter was optional after the second study suspension in a Roll-in subject. Previously enrolled subjects prior to suspension were also classified as Roll-in subjects; not counted in endpoint analysis	Subjects not Randomized to any treatment group and were not Roll-in subjects	Total of all reporting groups
Overall Number of Baseline Participants		125	125	30	17	5	302
Baseline Analysis Population Description		[Not Specified]
Age, Continuous; Mean (Standard Deviation); Unit of measure: Years
	Number Analyzed	125 participants	125 participants	30 participants	17 participants	5 participants	302 participants
		65 (11)	66 (10)	69 (10)	66 (9)	72 (11)	65.73 (10.54)
Sex: Female, Male; Measure Type: Count of Participants; Unit of measure: Participants
	Number Analyzed	125 participants	125 participants	30 participants	17 participants	5 participants	302 participants
	Female	23 18.4%	29 23.2%	4 13.3%	4 23.5%	2 40.0%	62 20.5%
	Male	102 81.6%	96 76.8%	26 86.7%	13 76.5%	3 60.0%	240 79.5%
Region of Enrollment; Measure Type: Number; Unit of measure: Participants
United States	Number Analyzed	125 participants	125 participants	30 participants	17 participants	5 participants	302 participants
		125	125	30	17	5	302

Outcome Measures

1. Primary Outcome

Title	Procedure-related Complication-free Rate
Description	A procedure-related complication is defined as an adverse event that results in death, a life-threatening complication, or a persistent or significant disability/incapacity or required intervention to prevent a permanent impairment of a body function or damage to a body structure. All adverse events related to the investigational or control devices or ablation procedure will be considered procedure-related events.
Time Frame	7 days post-procedure

Outcome Measure Data

Analysis Population Description

The primary outcome analysis is for a further subset of Randomized subjects only who underwent RF ablation; 220 subjects out of the total 302 subjects. All is consistent with the approved statistical analysis plan and information publicly available in the FDA Summary of Safety and Effectiveness Data (SSED) and BSC labeling, the Directions for Use.

Arm/Group Title	Blazer® Open-Irrigated Ablation Catheter	Control Catheter
Arm/Group Description:	Patients treated with the Blazer® Open-Irrigated Ablation Catheter Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter	Patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter
Overall Number of Participants Analyzed	109	111
Measure Type: Number; Unit of Measure: percentage of subjects
	92.7	98.2

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Blazer® Open-Irrigated Ablation Catheter, Control Catheter
	Comments	Note that analysis of the primary outcome was conducted for Randomized subjects only as prespecified in the study protocol. This is consistent analysis publicly available in the Summary of Safety and Effectiveness Data (SSED).
	Type of Statistical Test	Non-Inferiority or Equivalence
	Comments	The Primary Safety Endpoint was evaluated using a one-sided, non-inferiority test for two binomial proportions at an alpha-level of 0.05. A 95% confidence interval based upon a score test of the difference of proportion of subjects in the Investigational and Control Groups free from a procedure-related complication seven days post-procedure was constructed. The upper bound of the confidence interval was compared to 10%.
Method of Estimation	Estimation Parameter	Risk Difference (RD)
	Estimated Value	4.6
	Confidence Interval	(1-Sided) 95%; 9.78
	Estimation Comments	[Not Specified]

2. Primary Outcome

Title	Acute Success Rate
Description	Acute success is defined as demonstration of bidirectional cavo-tricuspid isthmus block (ie, lack of electrophysiological conduction through the isthmus) 30 minutes after the last radiofrequency application in the cavo-tricuspid isthmus with the investigational or control catheter only.
Time Frame	30 minutes after the last radiofrequency application in the cavo-tricuspid isthmus

Outcome Measure Data

Analysis Population Description

The primary outcome analysis is for a further subset of Randomized subjects only who underwent RF ablation; 220 subjects out of the total 302 subjects. All is consistent with the approved statistical analysis plan and information publicly available in the FDA Summary of Safety and Effectiveness Data (SSED) and BSC labeling, the Directions for Use.

Arm/Group Title	Blazer® Open-Irrigated Ablation Catheter	Control Catheter
Arm/Group Description:	Patients treated with the Blazer® Open-Irrigated Ablation Catheter Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter	Patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter
Overall Number of Participants Analyzed	109	111
Measure Type: Number; Unit of Measure: percentage of success
	87.2	89.2

3. Secondary Outcome

Title	Chronic Success Rate: All Treated Patients
Description	Chronic success is defined as freedom from recurrence of type 1 atrial flutter at 3-months post-procedure for all treated patients.
Time Frame	3 months post-procedure

Outcome Measure Data

Analysis Population Description

The secondary outcome analysis is for a subset of Randomized subjects only who underwent RF ablation; 220 subjects out of the total 302 subjects. All is consistent with the approved statistical analysis plan and information publicly available in the FDA Summary of Safety and Effectiveness Data (SSED) and BSC labeling, the Directions for Use.

Arm/Group Title	Blazer® Open-Irrigated Ablation Catheter	Control Catheter
Arm/Group Description:	Patients treated with the Blazer® Open-Irrigated Ablation Catheter Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter	Patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter
Overall Number of Participants Analyzed	109	111
Measure Type: Number; Unit of Measure: percentage of subjects
	74.3	80.2

4. Secondary Outcome

Title	Chronic Success Rate: Acute Success Patients
Description	Chronic success is defined as demonstration of acute success and freedom from recurrence of type 1 atrial flutter at 3-months post-procedure. Only randomized patients with acute procedural success will be included in this endpoint.
Time Frame	3-months post-procedure

Outcome Measure Data

Analysis Population Description

The secondary outcome analysis is for a further subset of Randomized subjects only who underwent RF ablation and classified as acute success; 194 of the total 302 subjects. All consistent with approved statistical analysis plan and information publicly available in the FDA SSED and BSC the Directions for Use.

Arm/Group Title	Blazer® Open-Irrigated Ablation Catheter	Control Catheter
Arm/Group Description:	Patients treated with the Blazer® Open-Irrigated Ablation Catheter Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter	Patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter
Overall Number of Participants Analyzed	95	99
Measure Type: Number; Unit of Measure: percentage of chronic success
	85.3	89.9

Adverse Events

Time Frame	Within 3 months of the index RF ablation procedure
Adverse Event Reporting Description	Only subjects at risk for adverse events, (Randomized and Roll-in for the Blazer Open-irrigated catheter and the Control Catheters) are included in the calculation of the adverse event rate. The calculation of the adverse event rate does NOT include the five Non-randomized subjects who were NOT treated with either the Blazer Open-irrigated catheter or the Control Catheter.
Arm/Group Title	Randomized Blazer® Open-Irrigated Ablation Catheter		Randomized Control Catheter		Roll-in Blazer® Open-Irrigated Ablation Catheter		Roll-in Control Catheter		Non-Randomized to Any Treatment Group
Arm/Group Description	Randomized patients treated with the Blazer® Open-Irrigated Ablation Catheter (procedure patients) Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter Note that only subjects at risk for an adverse event (treated subjects) are included in the calculation of the adverse event rates		Randomized patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter (procedure patients) Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter Note that only subjects at risk for an adverse event (treated subjects) are included in the calculation of the adverse event rates		Roll-in patients treated with the Blazer® Open-Irrigated Ablation Catheter (procedure patients) Blazer® Open-Irrigated Ablation Catheter: Blazer® Open-Irrigated Ablation Catheter Note that only subjects at risk for an adverse event (treated subjects) are included in the calculation of the adverse event rates		Roll-in patients treated with an open-irrigated radiofrequency ablation catheter that has received FDA market approval for the treatment of type 1 atrial flutter (procedure patients) Control Catheter: Open-irrigated radiofrequency ablation catheters that have received FDA market approval for the treatment of type 1 atrial flutter Note that only subjects at risk for an adverse event (treated subjects) are included in the calculation of the adverse event rates		Five subjects were not randomized to any treatment group and were not Roll-in subjects. Therefore, these five subjects were not treated with the Blazer Open-irrigated catheter or a Control catheter. Note that only subjects at risk for an adverse event (treated subjects) are included in the calculation of the adverse event rates
All-Cause Mortality
	Randomized Blazer® Open-Irrigated Ablation Catheter		Randomized Control Catheter		Roll-in Blazer® Open-Irrigated Ablation Catheter		Roll-in Control Catheter		Non-Randomized to Any Treatment Group
	Affected / at Risk (%)		Affected / at Risk (%)		Affected / at Risk (%)		Affected / at Risk (%)		Affected / at Risk (%)
Total	1/125 (0.80%)		0/125 (0.00%)		0/30 (0.00%)		0/17 (0.00%)		0/5 (0.00%)
Serious Adverse Events
	Randomized Blazer® Open-Irrigated Ablation Catheter		Randomized Control Catheter		Roll-in Blazer® Open-Irrigated Ablation Catheter		Roll-in Control Catheter		Non-Randomized to Any Treatment Group
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	7/109 (6.42%)		2/111 (1.80%)		5/28 (17.86%)		2/12 (16.67%)		0/5 (0.00%)
Cardiac disorders
Hypotension † 2 [1]	2/109 (1.83%)	2	0/111 (0.00%)	0	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
Congestive Heart Failure † 3 [2]	0/109 (0.00%)	0	1/111 (0.90%)	1	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
Junctional Rhythm † 5 [3]	1/109 (0.92%)	1	0/111 (0.00%)		0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
3rd Degree Heart Block †	0/109 (0.00%)	0	0/111 (0.00%)	0	0/28 (0.00%)	0	1/12 (8.33%)	1	0/5 (0.00%)	0
Atrial Fibrillation † [4]	0/109 (0.00%)	0	0/111 (0.00%)	0	2/28 (7.14%)	2	0/12 (0.00%)	0	0/5 (0.00%)	0
Chest pain iscemic †	0/109 (0.00%)	0	0/111 (0.00%)	0	1/28 (3.57%)	1	0/12 (0.00%)	0	0/5 (0.00%)	0
Myocardial perforation with tamponade †	0/109 (0.00%)	0	0/111 (0.00%)	0	1/28 (3.57%)	1	0/12 (0.00%)	0	0/5 (0.00%)	0
Nonsustained ventricular tachycardia † [5]	0/109 (0.00%)	0	0/111 (0.00%)	0	1/28 (3.57%)	1	0/12 (0.00%)	0	0/5 (0.00%)	0
Sinus Bradycardia †	0/109 (0.00%)	0	0/111 (0.00%)	0	0/28 (0.00%)	0	1/12 (8.33%)	1	0/5 (0.00%)	0
Infections and infestations
Urinary Tract Infection † 7 [6]	1/109 (0.92%)	1	0/111 (0.00%)	0	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
Nervous system disorders
Cardiovascular Accident (CVA) Resulting in Death † 1 [7]	1/109 (0.92%)	1	0/111 (0.00%)	0	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
Vasovagal Reaction † 4 [8]	1/109 (0.92%)	1	0/111 (0.00%)	0	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
Vascular disorders
Pseudoaneurysm with Hematoma † 6 [9]	0/109 (0.00%)	0	1/111 (0.90%)	1	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
Pseudoaneurysm † 6 [10]	1/109 (0.92%)	1	0/111 (0.00%)	0	0/28 (0.00%)	0	0/12 (0.00%)	0	0/5 (0.00%)	0
1 Term from vocabulary, CVA; 2 Term from vocabulary, Hypotension; 3 Term from vocabulary, CHF; 4 Term from vocabulary, Vasovagal Reaction; 5 Term from vocabulary, conduction disorder; 6 Term from vocabulary, Pseudoaneurysm; 7 Term from vocabulary, Urinary Tract Infect; † Indicates events were collected by systematic assessment; [1] Hypotension; [2] Congestive Heart Failure; [3] Junctional Rhythm Requiring Pacemaker Implantation; [4] AF; [5] NSVT; [6] Urinary Tract Infection; [7] Cardiovascular Accident (CVA) Resulting in Death; [8] syncope; [9] Pseudoaneurysm with Hematoma; [10] Pseudoaneurysm
Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events	0%
	Randomized Blazer® Open-Irrigated Ablation Catheter		Randomized Control Catheter		Roll-in Blazer® Open-Irrigated Ablation Catheter		Roll-in Control Catheter		Non-Randomized to Any Treatment Group
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	50/109 (45.87%)		61/111 (54.95%)		16/28 (57.14%)		7/12 (58.33%)		0/5 (0.00%)
Cardiac disorders
Ablation related Events † 1 [1]	6/109 (5.50%)	7	12/111 (10.81%)	13	3/28 (10.71%)	3	2/12 (16.67%)	2	0/5 (0.00%)	0
Cardiovascular related † 2 [2]	41/109 (37.61%)	56	52/111 (46.85%)	97	14/28 (50.00%)	18	5/12 (41.67%)	5	0/5 (0.00%)	0
General disorders
Non-cardiovascular † 3 [3]	11/109 (10.09%)	12	11/111 (9.91%)	16	4/28 (14.29%)	4	1/12 (8.33%)	1	0/5 (0.00%)	0
1 Term from vocabulary, Procedure-related; 2 Term from vocabulary, Cardiovascular; 3 Term from vocabulary, Non-cardiovascular; † Indicates events were collected by systematic assessment; [1] events related to ablation procedure; [2] arrhythmias, chest pain, CVA, symptoms; [3] Non-cardiovascular

Limitations and Caveats

Two interim study suspensions occurred during enrollment that did not impact the integrity of the data and subsequent analyses.

More Information

Certain Agreements

Principal Investigators are NOT employed by the organization sponsoring the study.

There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.

Results Point of Contact

• Name/Title: Timothy Meyer; Director of Clinical Trials
• Organization: Boston Scientific
• Phone: 651 581 3425
• EMail: Timothy.meyer@bsci.com

• Responsible Party: Boston Scientific Corporation
• ClinicalTrials.gov Identifier: NCT01253200
• Other Study ID Numbers: BLOCk-CTI
• First Submitted: November 21, 2010
• First Posted: December 3, 2010
• Results First Submitted: March 9, 2017
• Results First Posted: February 15, 2018
• Last Update Posted: March 19, 2018