Diet, Nutrition, and Managing Obesity

Abstract

Questions regarding diet, nutrition, and weight loss frequently arise during visits with patients with hypertrophic cardiomyopathy (HCM). In distinction to other chronic cardiac conditions, such as heart failure with reduced ejection fraction or following myocardial infarction, there is a distinct paucity of high-quality clinical trial data to inform decision-making, and current guidelines avoid making any specific recommendations in much of the lifestyle sphere, including these particular issues. In the meantime, providers and patients need to feel comfortable with an approach which integrates best available data in patients with HCM, extrapolation from other cardiac conditions distinct from HCM, and a healthy degree of common sense.

Questions

• 1. A patient with HCM comes to your office for consultation. She has NYHA class II symptoms of dyspnea and CCS class II symptoms of angina. She also mentions to you that for the past several years, she has noticed chest pain after eating meals, particularly larger ones. Her exam is notable for an S4 and a 3/6 LVOT murmur which accentuates with Valsalva. The most likely cause of her postprandial symptoms is:

  • A. Coronary insufficiency from high-grade proximal vessel CAD

  • B. Hiatal hernia

  • C. Microvascular dysfunction

  • D. Worsening LVOT obstruction and tachycardia with eating

  • E. Esophageal spasm

  While any of these can cause chest pain, the description is classic for postprandial angina in a patient with HCM. Splanchnic vasodilation results in a drop in systemic vascular resistance which, in turn, leads to worsening dynamic LVOT gradient and a compensatory tachycardia (D). This is thought to lead to increased oxygen demand and resultant ischemia.

• 2. A patient with HCM comes to your office for consultation. He is asymptomatic and, while he has no resting gradient, he has a 70mmHg gradient with exercise. He is not currently interested in medical therapies but is wondering about dietary advice. In addition to recommending avoidance of dehydration, you should tell him:

  • A. To follow a low-fat/low-cholesterol diet

  • B. To follow a salt-restricted diet

  • C. To follow a low-carbohydrate ketogenic diet

  • D. That there is currently no macronutrient dietary recommendation for patients with HCM

  There are currently no dietary recommendations for patients with HCM to follow (D). The most important thing appears to be to maintain a healthy weight. Specific macronutrient recommendations may be made if the patient develops additional comorbidities, such as diabetes or hyperlipidemia. Salt-restricted and low-carbohydrate diets may result in lower circulating blood volume and should be used under the observation of the physician.

• 3. A 45-year-old patient with HCM presents to your clinic for follow-up. He is currently moderately symptomatic on beta blocker therapy. His BMI is 36kg/m2. Which of the following is not true relating to the association between this patient’s BMI and HCM?

  • A. Elevated BMI is associated with greater LV mass index among patients with HCM.

  • B. HCM patients with elevated BMI are more likely to have severely symptomatic disease compared with those with normal BMI.

  • C. Obese patients with HCM have a higher mortality rate than normal weight patients.

  • D. Obesity is associated with higher prevalence of late gadolinium enhancement by MRI.

  Obesity is associated with greater LV mass, higher severity of HF symptoms, and the presence of scar by MRI. Despite this, it has not been associated with higher risk of death (C). It is not at this time known whether obesity is “protective” against death – as the obesity paradox has been shown for coronary artery disease and HFrEF.

• 4. A 37-year-old patient with nonobstructive HCM comes to your office inquiring about starting an exercise regimen. Which of the following should you tell her?

  • A. She should avoid any time of exercise until data come out for safety.

  • B. Moderate levels of activity appear to be safe, at least over the short term.

  • C. Singles tennis would be preferable to bicycling according to the US guidelines.

  • D. The presence of an ICD would allow her to participate freely in any intensity of exercise.

  At least low-intensity exercise can be recommended based on current guidelines. RESET-HCM demonstrated that moderate-intensity activity was safe over the short term and was associated with modest increases in VO2 (B). The US guidelines assign a point score to various aerobic activities. Singles tennis (score 0) is regarded in that schema as higher risk than bicycling (score 4). The presence of an ICD does not obviate limitations on activity based on current guideline recommendations.

• 5. Although not specifically studied in HCM, in small studies alternative lifestyle interventions such as yoga, tai chi, and meditation have been shown in heart failure patients to:

  • A. Reduce the frequency of ICD firings.

  • B. Improve perceived quality of life.

  • C. Improve maximal oxygen uptake.

  • D. All of the above.

  Although the data are limited to small, short-term trials, these therapeutic lifestyle interventions appear to be associated with both objective and subjective improvements in disease status among patients with HFrEF (D). It seems reasonable, therefore, to offer them to patients with HCM.