Heartfelt Concerns

From Cardiology for the Primary Physician, sponsored by the Cardiovascular Division at
the Medical University of South Carolina, Charleston

Educational Objectives

The goal of this program is to improve management of sudden cardiac death in hypertrophic cardiomyopathy (HCM), and to review lifestyle modifications for pro-moting cardiovascular health and longevity. After hearing and assimilat­ing this program, the clinician will be better able to:

1.   Describe general features of sudden death in HCM.

2.   List risk factors for sudden cardiac death.

3.   Evaluate patients for risk for sudden cardiac death, based on clinical findings.

4.   Recommend healthy diet choices to reduce cardiovascular risk.

5.   Counsel patients about health effects of physical activity, mental stress, and media.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Vogel is on the Speakers’ Bureau for Pfizer. Dr. Spencer and the planning committee reported nothing to disclose.

Acknowledgements

Drs. Spencer and Vogel spoke in Charleston, SC, at Cardiology for the Primary Physician, presented May 27-29, 2009, by the Medical University of South Carolina. The Audio-Digest Foundation thanks the speakers and the Medi­cal University of South Carolina for their cooperation in the production of this program.

Sudden Cardiac Death in Hypertrophic Cardiomyopathy

William H. Spencer III, MD, Professor of Medicine, Medical University of South Carolina, Charleston

General features of sudden cardiac death in hypertrophic cardiomyopathy (HCM): usually occurs in young people with no or mild previous symptoms; usually occurs when patients sedentary; known to occur with bursts of activity (eg, while playing football or baseball); may occur at any age; histologic features  —  myofibril disarray; ar­teritis (can provoke ischemia); abnormal vascular reserves; progressive fibrosis

Mechanism of sudden death: polymorphic ventricular tachycardia (VT) degenerating into ventricular fibrillation (VF); not associated with bradyarrhythmias

Treatment and prevention of sudden death: lifetime therapy with amiodarone impractical for young patients; no long-term medications available for prevention; disopyramide (Norpace) treats symptoms of heart failure, but not shown to affect incidence of sudden death; implantable cardioverter defibrillator (ICD)  —  only therapy available; consider risks in young patients; emotional decision

Predicting sudden death: no test available to predict risk for sudden death or benefit from ICD; electrophysiology (EP) studies not useful; some potential benefits of Holter monitoring and ambulatory electrocardiography (ECG) monitoring; T-wave alternans testing “had the most promise; however, we have not been able to make it work”; monitoring blood pressure (BP) response to exercise potentially valuable

Clinical risk factors for sudden death in HCM: history of cardiac arrest; recurrent unexplained syncope; sudden cardiac death in first-degree family member <55 yr of age; nonsustained VT on Holter monitoring; massive (sep­tum ³3 cm) left ventricular hypertrophy (LVH); hypotensive response to exercise; additional risk factors  —left ventricular outflow tract (LVOT) obstruction; coronary artery disease; atrial fibrillation (AF); high-risk muta­tions; intense sudden-burst exercise; 55% of people with HCM have no risk factors (»2% have 3 risk factors, 10% have 2 risk factors, 33% have 1 risk factor); no history of cardiac arrest and one risk factor for sudden death  —  ICD for primary prevention; annual incidence of appropriate ICD discharge, 4% to 6% (11%-12% with positive history of cardiac arrest)

Recurrent unexplained syncope: multifactorial; VT or VF; can be related to exertional hypotension; patients predis­posed to neurocirculatory syncope; basal regulatory system abnormal (consider atropine); can be caused by su­praventricular arrhythmia (eg, onset or offset of AF), LVOT obstruction, and complete heart block or sinus node dysfunction (rare); patients with unexplained syncope during 6 mo preceding examination had higher incidence of sudden death; nonrecurrent syncope has low specificity and sensitivity as risk factor for sudden cardiac death

Family history of sudden death: emotional factor; discuss ICD

Gene mutations: prognosis of genotypes ranges from very poor (“malignant”) to very good; genotype testing  —  not valuable for identifying risk; identification of and testing for 9 to 12 genes related to HCM available; covered by insurance; expensive ($7400); of limited value (ie, not all people with positive genotype develop manifestations of HCM; phenotype varies widely); epigenetic factors (eg, environment, associated illnesses) affect expression of gene; patients with positive genotype and no signs of HCM may be given drug (eg, statin, losartan) to prevent fu­ture expression of HCM (studies currently underway); children of patients with HCM and positive genotype can be tested for gene, but gene not always identified; chance of identifying gene in young person with HCM, 80% (20% in older person); heterogenous illness; counseling helpful; troponin T gene mutations associated with high incidence of sudden death (genotyping potentially useful)

Nonsustained VT: increases with age (likely due to increasing fibrosis); more common in patients >45 yr of age; no statistical significance in patients >30 yr of age, but major risk factor in patients <30 yr of age; progressive, linear increase in incidence of sudden death based on maximal LV wall thickness (significant risk at 2.5-3.0 cm; con­sider ICD in young patients)

Hypotensive response to exercise: variably defined (eg, <20 mm Hg or <30 mm Hg rise in systolic pressure, or drop in systolic pressure with exercise); maximum gradient in HCM occurs when exercise stopped; patients unable to increase stroke volume (instead, stroke volume decreases with exercise) likely due to global LV ischemia and systolic dysfunction; over time, patients have higher incidence of sudden death, compared to those with normal BP response; unpublished data show that alcohol septal ablation (ASA) successful in 50% of patients with HCM and LVOT obstruction (had normotensive response to exercise after procedure)

Evaluating risk: additive effect of 2 to 4 risk factors (decreases incidence of survival over 10 yr); delayed gadolinium enhancement of magnetic resonance imaging (MRI)  —can identify level of fibrosis in HCM; patients with nonsus­tained VT and high degree of fibrosis have more couplets and premature ventricular contractions (PVCs); expen­sive; time-consuming; statin stress testing and positron emission tomography (PET)  —  for patients with ischemia and ab-normal vascular reserves; study showed abnormal myocardial blood flow had risk ratio of 9.6 for sudden death; easy to perform; fractionation of pace-evoked ventricular ECG  —  correlates to amount of fibrous tissue in myocardium; indirect way of measuring fibrosis; application in clinical practice unlikely

Effect of LVOT obstruction: amount of obstruction affects outcome (“more obstruction, more sudden death”); data show patients with LVOT obstruction who underwent myectomy had only one appropriate ICD discharge over 10 yr; relief of obstruction decreases incidence of sudden death; study —patients with obstructive HCM, significant outflow tract gradient (>30 mm Hg at rest), and 1.5 risk factors (ie, considered at high risk for sudden death) re­ceived ICD and underwent ASA; at 3-yr follow-up, study saw 9 appropriate ICD discharges with annual appropri­ate ICD discharge rate of 2.8%; demonstrates that  ASA not proarrhythmic and considered effective for patients with symptomatic HCM

Summary: high incidence of sudden cardiac death in young people; middle-aged patients have symptoms of heart failure and angina; in elderly, outcome of sudden death similar to age- and gender-matched population

Questions and answers: small apical aneurysms  —  patients with apical HCM generally have benign outcome; aneu­rysm of apex from infarct leads to death due to heart failure or VA; some aneurysms resolve with relief of outflow tract obstruction or midcavity obstruction

Strategies for a Better, Longer Life

Robert A. Vogel, MD, Professor of Medicine, University of Maryland School of Medicine, and Chief Medical Officer, Pritikin Longevity Center, Baltimore

Introduction: according to data from 2000, one-third of total deaths in United States premature, and attributable to problems of lifestyle (eg, tobacco smoking, diet and activity, alcohol use)

Obesity and cardiovascular risk: Can Rapid risk stratification of Unstable angina patients Suppress ADverse out­comes with Early implementation of the ACC/AHA guidelines (CRUSADE) Quality Improvement Initiative showed every extra 10 lb of body weight (»2 body mass index [BMI] units) shortens period before onset of heart disease by 1.5 yr; average American 30 lb overweight, so myocardial infarction predicted to occur 5 yr sooner; decreasing dietary intake by 100 calories per day, or burning 100 calories per day through physical activity can lead to 10-lb weight loss in 1 yr

Identifying obesity: body weight  —  person 5’6” overweight at 155 lb, obese at 189 lb; person 6’0” overweight at 184 lb, obese at 220 lb; waist circumference  —  goal for men, <40 in; goal for women, <35 in; waist-to-hip ratio  —  best predictor of cardiovascular risk; BMI not strong predictor of cardiovascular risk, although risk fac­tors increase as BMI increases; consider ethnicity (eg, upper limit of normal waist circumference in south Asian men, 35 in)

Dietary approaches: volumetric approach  —  start every meal with whole grains, soup, or salad (eg, include oatmeal at breakfast, salad at lunch, and soup at dinner); shown to reduce caloric intake by 100 calories at each meal; avoid high-calorie salad dressings; diet beverages  —  data show 20-lb weight difference in 8 yr between regular beverage drinkers and diet beverage drinkers; every study shows more weight gain in regular beverage drinkers, compared to diet beverage drinkers; some suggest that sweetened, zero-calorie beverages condition mind to “not expect” calo­ries when consuming sweet things; determine how many calories per day patients consume in beverages; average American drinks 20% of total calories, and 300 calories per day in soda; average American eats and drinks 150 lb of raw sugar per year (teenagers, 250 lb per yr); fast food  —  eating fast food ³2 times/wk results in 10-lb weight gain every 15 yr, and doubles risk for diabetes; average fast food meal contains 1050 calories and 50 g of fat; snacking  —  “a habit; not a dietary necessity”; avoid dry snacks (eg, candy, chips); choose snacks high in fiber and water content; physical activity  —  in addition to reduction in caloric intake; study found women who exercised more lost more weight, and kept it off; recommend walking (eg, use pedometer; walk 3000 more steps per day than number usually walked)

Types of diets: general  —  green leafy vegetables, raw and cooked vegetables, and fruit reduce heart disease; meats, fried foods, and salty foods increase heart disease; grains “neutral”; Mediterranean-style diet  —  shown to reduce total mortality, cancer mortality, and neurologic diseases; characterized by generous amounts of whole grains, fruits, beans, vegetables, fish, skim milk products, and limited amounts of meat; study recommends canola oil (con­tains 10 times more omega-3 fatty acids and one-third less saturated fat than olive oil); removal of olive oil from diet not shown to change cholesterol or body weight, but trials saw 72% decrease in cardiovascular events, 60% de­crease in mortality, and 80% decrease in cancer; low-fat (eg, Ornish Diet) or high-fat diets (eg, Atkins Diet)  —low-fat diets reduce low-density lipoprotein (LDL), but high-fat diets may be more appropriate for controlling high-density lipoprotein (HDL) and triglycerides; for other biologic markers (eg, inflammation, endothelial function), consider absolute relationship between vascular health and intake of saturated fat; avoid oils high in saturated fat (eg, palm and coconut oil)

Dietary modifications: alcohol  —  study comparing exclusive red wine drinkers to exclusive white wine drinkers found equal relative risk for heart disease between groups; greater benefits seen in patients with coronary heart dis­ease who drink alcohol daily, compared to those who drink only on weekends; salt  —  Americans consume 3 to 4 times more salt than needed; most salt consumed through processed, canned, and restaurant food; sodium reduction results in lowered BP and improved endothelial function; reducing sodium intake by 25% reduced cardiovascular events by 30% and mortality by 20%; Institute of Medicine recommends 1500 mg per day of sodium

Tobacco smoking cessation: lifetime smokers lose 7 yr of life; 1 min of life lost with every minute of smoking; dis­cuss with younger (eg, 25 yr of age) smokers; strategies include telling women that smoking causes wrinkles

Physical fitness: “most fit, least dead; least fit, most dead”; excessive exercise  —  middle-aged marathon runners have cardiovascular risk equivalent to those with heart disease (10-yr cardiovascular event rate, 21%); be cautious with extreme athletes; hours of myocardial O₂ consumption (mVo₂) >80% produce oxidative stress, endothelial dysfunc­tion, and cause atherosclerosis; discontinuous, interval-based exercise (eg, run for 5 min, walk for 5 min) recom­mended; continuous jogging can result in orthopedic damage and minimal cardiovascular benefit

Mental stress and media: mental stress  —  study found endothelial function diminished for 4 hr in individuals told they were caught shoplifting; video  —  physiologic effect on endothelial function as consequence of video-watching same as that of living through experience; music  —  best biologic response seen with country-western music (“if you like it”)

Questions and answers: vitamin D  —  50% of Americans deficient; apply sunscreen after 10 min of sun exposure; supplementation recommended; traditional French Diet  —relatively low calorie; limited snacking; French lifestyle includes walking and bicycling; in France, incidence of heart disease lower than in United States (but reporting of coronary heart disease on death certificates different from reporting in United States); longevity in France unre­markable

Suggested Reading

Ackerman MJ et al: Prevalence and age-dependence of malignant mutations in the beta-myosin heavy chain and tropo­nin T genes in hypertrophic cardiomyopathy: a comprehensive outpatient perspective. J Am Coll Cardiol 39:2042, 2002; Ciampi Q et al: Hemodynamic determinants of exercise-induced abnormal blood pressure response in hypertrophic car­diomyopathy. J Am Coll Cardiol 40:278, 2002; de Lorgeril M et al: The Mediterranean-style diet for the prevention of cardiovascular diseases. Public Health Nutr 9:118, 2006; Dhingra R et al: Soft drink consumption and risk of develop­ing cardiometabolic risk factors and the metabolic syndrome in middle-aged adults in the community. Circulation 116:480, 2007; Elliott PM et al: Left ventricular outflow tract obstruction and sudden death risk in patients with hyper­trophic cardiomyopathy. Eur Heart J 27:1933, 2006; Elliott PM et al: Sudden death in hypertrophic cardiomyopathy: identification of high risk patients. J Am Coll Cardiol 36:2212, 2000; Ghiadoni L et al: Mental stress induces transient endothelial dysfunction in humans. Circulation 102:2473, 2000; Iqbal R et al: Dietary patterns and the risk of acute myocardial infarction in 52 countries: results of the INTERHEART study. Circulation 118:1929, 2008; Klatsky AL et al: Alcohol use and cardiovascular disease: the Kaiser-Permanente experience. Circulation 64:III 32, 1981; Moon JC et al: Toward clinical risk assessment in hypertrophic cardiomyopathy with gadolinium cardiovascular magnetic reso­nance. J Am Coll Cardiol 41:1561, 2003; Renaud S et al: Cretan Mediterranean diet for prevention of coronary heart disease. Am J Clin Nutr 61:1360S, 1995; Rolls BJ et al: Salad and satiety: energy density and portion size of a first-course salad affect energy intake at lunch. J Am Diet Assoc 104:1570, 2004; Spirito P et al: Magnitude of left ventricu­lar hypertrophy and risk of sudden death in hypertrophic cardiomyopathy. N Engl J Med 342:1778, 2000; Vogel RA et al: The Pritikin Edge. New York: Simon & Schuster; 2008; Wisløff U et al: Superior cardiovascular effect of aerobic in­terval training versus moderate continuous training in heart failure patients: a randomized study. Circulation 115:3086, 2007.