NCT05025644

Quantitative Assessment of Hypertrophic Obstructive Cardiomyopathy With Intraoperative Three-dimensional Transesophageal Echocardiography Under Provocative Dobutamine Stress Test

• Status: Unknown
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 60 (estimated)
• Sponsor: University Health Network, Toronto · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

The objectives of this study are to determine if the left ventricle outflow tract (LVOT) gradients may be reproduced with dobutamine (DBT) provocation test in obstructive HCM patients under general anesthesia and to analyze the change in anatomic LVOT area and pressure gradients (PG) before and after septal myectomy. If the DBT stress test can reproduce preoperative gradients in HCM patients during septal myectomy surgery, surgeons will have the opportunity to assess the quality of the surgical procedure depending on the obtained gradients with DBT stress test after surgery when gradients can't be reproduced during general anesthesia after myectomy, and decide if further myectomy is required, saving a re-operation on the patient in the future.

Detailed description

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy. Echocardiography is the noninvasive method of choice for the evaluation of morphologic and functional abnormalities in HCM. It is of paramount importance to distinguish between obstructive or non-obstructive HCM, based on the presence or absence of left ventricle outflow tract (LVOT) gradient using continuous wave Doppler (CWD), under resting and/or provocable conditions. HCM can then be divided into three different subgroups. When the gradient at rest is ≥ 30 mmHg the HCM is considered obstructive (HOCM); when the gradient is \<30 mmHg at rest but ≥ 30 mmHg with provocation, the HCM is considered latent obstructive, and finally, non-obstructive occurs when the gradient is \< 30mmHg at rest or with provocation. The gold standard technique to treat symptomatic HOCM is the surgical transaortic septal myectomy, when the resting gradient or the provocable gradient is ≥50 mmHg. Hemodynamic conditions may change and lead to worsening or improvement in LVOT obstruction during general anesthesia. LVOT gradients during surgery should be measured under reproducible conditions possibly mimicking preoperative hemodynamics. Dobutamine is a well-known inotropic agent, capable to induce sub-aortic gradients in HOCM. The development of a dynamic LVOT gradient during this test is a pharmacological phenomenon with no clinical significance, not been associated with increased frequency of chest pain, shortness of breath or ischemic wall motion abnormalities, because obstruction resolves after termination of dobutamine (DBT) infusion.

Conditions

• Hypertrophic Obstructive Cardiomyopathy

Interventions

Type	Name	Description
DRUG	Pre and post-CPB Drug: Dobutamine Hydrochloride	* Pre-CPB provocation test with DBT stress test will be started (starting at 5 mcg/kg/min, increasing every 3 min, to 10, 15 and 20 mcg/kg/min) until a PG ≥ 50mmHg is achieved (DBT peak dose). The DBT peak dose (DBT-pd) will be recorded. * Post-CPB provocation test at the DBT-pd achieved preoperatively.
DRUG	Post-CPB Drug: Dobutamine Hydrochloride	* Pre-CPB no intervention will be required. * Post-CPB provocation test with DBT stress test will be started (starting at 5 mcg/kg/min, increasing every 3 min, to 10, 15 and 20 mcg/kg/min) or until postoperative provocable PG is \>16 mmHg.

Timeline

• Start date: 2023-03-01
• Primary completion: 2024-08-01
• Completion: 2024-11-01
• First posted: 2021-08-27
• Last updated: 2022-11-08