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

Phase 4

Not yet recruiting

• Conditions: Hypertrophic Obstructive Cardiomyopathy

• Registration Number: NCT05025644
• Lead Sponsor: University Health Network, Toronto

Brief 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.

Study Timeline

• Study First Submitted: 2021-08-11
• Study First Submitted QC: 2021-08-24
• Study First Posted: 2021-08-27
• Status Verified: 2022-11
• Last Update Submitted: 2022-11-04
• Last Update Posted: 2022-11-08
• Study Start: 2023-03
• Primary Completion: 2024-08
• Study Completion: 2024-11

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 60

Inclusion Criteria

1. HOCM refractory to medical treatment with symptoms like syncope, angina or NYHA functional classes III and IV, with a resting gradient or provocable gradient equal or greater than 50 mmHg, requiring surgical intervention.
2. Absence of other cardiac or systemic diseases capable of producing hypertrophy.
3. Sinus rhythm.

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Exclusion Criteria

1. Patient refusal.
2. Patient unable to give consent.
3. TEE contraindication.
4. Different rhythm than sinus.
5. Other systemic diseases capable of producing hypertrophy.
6. Severe Aortic or coronary artery pathology.

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Analyze if TEE immediate post-myectomy LVOT gradients, may be reproduced with provocation dobutamine test in HOCM patients, when compared to TTE LVOT gradients performed within 6 months post-myectomy, to prove septal myectomy efficacy.	Pre-operative up to 6 months, Immediate Intra-operative Pre-myectomy, Immediate Intra-operative Post-myectomy and Post-operative up to 6 months	The preoperative gradients obtained by TTE, with and without stress test, within 6 months pre-myectomy, will be compared with the intraoperative TEE pre-myectomy gradients at baseline (before and after DBT stress test).; The post-myectomy TEE gradients (before and after DBT stress test), will be compared with the follow up TTE gradients with and without stress test, performed within 6 months post-myectomy, to assess short term outcomes.