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| ID | Type | Description | Link |
|---|---|---|---|
| NIH grant, GCRC MO1 RR000080 |
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Background. In congenital long QT syndrome type 1 (LQT1), episodes of ventricular tachycardia are usually triggered by exercise and can be prevented in most patients by beta-blocker therapy. In addition, LQT1 associated with a normal resting QT interval can be unmasked by the abnormal QT response to exercise testing (failure of the QT interval to shorten normally). Preliminary data from our laboratory show that the exercise QT intervals of patients with LQT1 are partially normalized by beta-blocker therapy. It is still currently not known if beta-blockers modify the QT/heart rate relationship (a primary effect on repolarization) or if the "normalizing" effect is due to the inability of subjects on beta-blockers to attain sufficiently high workloads (due to reduced heart rate) for prolongation to occur. Moreover, the physiologic response of the exercise QT interval to beta-blockers in healthy control subjects is not known.
Objective. The objective of this study is to define the impact of beta-blocker therapy on the QT response to exercise and recovery in normal subjects.
Methods. Approximately 36 healthy adult subjects age-matched to previously studied LQT1 subjects will undergo 1) screening history, 2) two weeks of beta-blocker therapy ending in an exercise test, and 3) two weeks of placebo therapy ending in an exercise test. Beta blocker and placebo will be given in random order in a double-blind fashion. The QT response to exercise and recovery will be compared between drug-free and beta-blocker-treated states. These data will be compared to those previously collected for LQT1 subjects.
Implications. These results will provide new information about the effect of beta-blocker therapy on repolarization parameters in normal subjects, and will provide a context in which to interpret the previous findings that beta-blocker administration modifies the QT response to exercise in LQT1 subjects.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| 1 | Placebo Comparator | Subjects are assigned to placebo. |
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| 2 | Active Comparator | Subjects will take propranolol LA 80 mg daily for one week then 160 mg for one week followed by the exercise test. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Placebo | Drug | Placebo will be given 1 pill daily for a week, then 2 pills daily, followed by the exercise test. |
|
| Measure | Description | Time Frame |
|---|---|---|
| QTc Response to Exercise on Versus Off Beta-blocker. | To minimize the effect of heart rate on QT, QT was measured at heart rates between 100 and 110 beats per minute during exercise (on and off beta-blocker) and during recovery (on and off beta-blocker). | 2 weeks on each treatment then exercise test |
| Measure | Description | Time Frame |
|---|---|---|
| Tpeak-end Interval (Tpe) | Tpeak-end interval was measured at rest, exercise, and recovery on placebo and on propranolol. | Measured after 2 weeks on each intervention |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Elizabeth S Kaufman, MD | MetroHealth Medical Center | Principal Investigator |
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| ID | Title | Description |
|---|---|---|
| FG000 | All Participants | All participants were randomized to one of 2 sequences, in which they received either propranolol first, then placebo, or placebo first, then propranolol. |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
|
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| ID | Title | Description |
|---|---|---|
| BG000 | All Subjects | Subjects will take propranolol LA 80 mg or placebo daily for one week then propranolol LA 160 mg for one week or 2 placebo pills, followed by the exercise test. The participants will be randomized to one of 2 sequences: placebo first or propranolol first. |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Categorical | Count of Participants |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | QTc Response to Exercise on Versus Off Beta-blocker. | To minimize the effect of heart rate on QT, QT was measured at heart rates between 100 and 110 beats per minute during exercise (on and off beta-blocker) and during recovery (on and off beta-blocker). | Please note that this was a crossover study. There were 35 subjects and each subject completed both the placebo and beta-blocker arm. | Posted | Mean | Standard Deviation | ms | 2 weeks on each treatment then exercise test |
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Placebo | Subjects are assigned to placebo. |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Dr. Elizabeth Kaufman | MetroHealth Medical Center | 216-778-2349 | ekaufman@metrohealth.org |
| ID | Term |
|---|---|
| D008133 | Long QT Syndrome |
| D009043 | Motor Activity |
| ID | Term |
|---|---|
| D001145 | Arrhythmias, Cardiac |
| D006331 | Heart Diseases |
| D002318 | Cardiovascular Diseases |
| D000075224 | Cardiac Conduction System Disease |
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| Propranolol LA | Drug | Subjects will receive propranolol LA 80 mg one pill daily for 1 week then 2 pills daily for 1 week followed by exercise test. |
|
| Participants |
|
| Age Continuous | Mean | Standard Deviation | years |
|
| Sex: Female, Male | Count of Participants | Participants |
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| Region of Enrollment | Number | participants |
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| Units |
|---|
| Counts |
|---|
| Participants |
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| Secondary | Tpeak-end Interval (Tpe) | Tpeak-end interval was measured at rest, exercise, and recovery on placebo and on propranolol. | Posted | Mean | Standard Deviation | ms | Measured after 2 weeks on each intervention |
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| 0 |
| 35 |
| 0 |
| 35 |
| EG001 | Propranolol | Subjects will take propranolol LA 80 mg daily for one week then 160 mg for one week followed by the exercise test. | 0 | 35 | 0 | 35 |
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| D006330 | Heart Defects, Congenital |
| D018376 | Cardiovascular Abnormalities |
| D000013 | Congenital Abnormalities |
| D009358 | Congenital, Hereditary, and Neonatal Diseases and Abnormalities |
| D010335 | Pathologic Processes |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D001519 | Behavior |
| Recovery |
|