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Hemodynamic determinants of exercise-induced abnormal blood pressure response in hypertrophic cardiomyopathy
Quirino Ciampi1, Sandro Betocchi, Raffaella Lombardi
1Department of Clinical Medicine, Cardiovascular and Immunological Sciences, Federico II University School of Medicine, Via S. Pansini 5, Naples, I-80131 Italy.
Insights
Patients with hypertrophic cardiomyopathy (HCM) experience abnormal exercise hemodynamics, particularly those with abnormal blood pressure responses. This exercise-induced left ventricular systolic dysfunction indicates hemodynamic instability and a high risk of sudden cardiac death.
Area of Science:
- Cardiology
- Exercise Physiology
- Medical Imaging
Background:
- About one-third of hypertrophic cardiomyopathy (HCM) patients exhibit a blunted blood pressure response during exercise.
- This abnormal response is linked to an elevated risk of sudden cardiac death.
Purpose of the Study:
- To evaluate exercise hemodynamics in hypertrophic cardiomyopathy (HCM) patients.
- To compare patients with and without exercise-induced abnormal blood pressure (BP) response.
- To assess left ventricular (LV) function using ambulatory radionuclide monitoring (VEST).
Main Methods:
- Forty-three HCM patients and 14 controls underwent maximal exercise testing with VEST monitoring.
- LV function parameters (ejection fraction, stroke volume, cardiac output, systemic vascular resistance) were analyzed at rest and peak exercise.
- Hemodynamic data were expressed as a percentage of baseline values.
Main Results:
- HCM patients showed decreased ejection fraction and stroke volume during exercise, unlike controls.
- Cardiac output increased significantly less in HCM patients compared to controls.
- Patients with an abnormal BP response exhibited greater reductions in ejection fraction and stroke volume, and a smaller increase in cardiac output.
Conclusions:
- Abnormal hemodynamic adaptation to exercise in HCM patients is quantitatively different based on BP response.
- An abnormal BP response is associated with exercise-induced LV systolic dysfunction.
- This dysfunction contributes to hemodynamic instability and increases the risk of sudden cardiac death in HCM patients.
Objectives:
We sought to assess the hemodynamics of exercise in patients with hypertrophic cardiomyopathy (HCM), with and without an exercise-induced abnormal blood pressure (BP) response, by ambulatory radionuclide monitoring of left ventricular (LV) function with the VEST device (Capintec Inc., Ramsey, New Jersey).
Background:
Blood pressure fails to increase >20 mm Hg during exercise in about one-third of patients with HCM. This carries a high risk of sudden death.
Methods:
Forty-three patients with HCM and 14 control subjects underwent maximal symptom-limited exercise on a treadmill during VEST. The VEST data were averaged for 1 min and analyzed at baseline, 3 min and peak exercise. The LV end-diastolic, end-systolic and stroke volumes, cardiac output and systemic vascular resistance were expressed as the percentage of baseline.
Results:
Ejection fraction and stroke volume fell in patients with HCM, although they increased in control subjects (p < 0.001 and p = 0.002, respectively). Cardiac output increased significantly more in control subjects than in patients with HCM (p = 0.001). In 17 patients with HCM (39%) with an abnormal BP response, ejection fraction and stroke volume fell more (p = 0.032 and p = 0.009, respectively) and cardiac output increased less (p = 0.001) than they did in patients with HCM with a normal BP response. Systemic vascular resistance decreased similarly in patients with HCM, irrespective of the BP response.
Conclusions:
In patients with HCM with and without an abnormal BP response, abnormal hemodynamic adaptation to exercise was qualitatively similar but quantitatively different. An abnormal BP response was associated with exercise-induced LV systolic dysfunction. This causes hemodynamic instability, associated with a high risk of sudden cardiac death.