Severe LVOT obstruction in HCM: effects on exercise capacity and outcomes from cardiopulmonary exercise testing...

Area of Science:

• Cardiology
• Internal Medicine
• Clinical Research

Background:

• Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular outflow tract (LVOT) obstruction, impacting patient function and outcomes.
• The precise clinical significance of varying LVOT obstruction severity in HCM remains a subject of ongoing investigation.

Purpose of the Study:

• To investigate the correlation between the severity of LVOT gradient and exercise performance.
• To assess the long-term prognosis of patients with HCM based on LVOT gradient severity.
• To utilize combined cardiopulmonary exercise testing and stress echocardiography (TTE-CPET) for this evaluation.

Main Methods:

• Retrospective analysis of 388 HCM patients who underwent TTE-CPET.
• Stratification into four groups based on peak LVOT gradient: <30 mmHg, 30-49 mmHg, 50-79 mmHg, and ≥80 mmHg.
• Comparison of clinical, echocardiographic, and CPET data, with a composite primary outcome including clinical deterioration and adverse events over a median 7.4-year follow-up.

Main Results:

• Severe obstruction (≥80 mmHg) was associated with significantly lower peak VO2, elevated pulmonary pressures, advanced diastolic dysfunction, and increased symptoms.
• Patients with severe obstruction exhibited a higher incidence of adverse events and worse event-free survival compared to those with less severe obstruction.
• A peak gradient of ≥80 mmHg independently predicted adverse outcomes, even after multivariable adjustment.

Conclusions:

• Severe dynamic LVOT obstruction identifies a high-risk HCM subgroup with diminished exercise capacity and a poorer long-term prognosis.
• Intermediate LVOT gradients (30-79 mmHg) may necessitate close clinical monitoring due to potential early structural or functional changes.
• TTE-CPET is a valuable tool for risk stratification and guiding early interventions in HCM patients.