What is the next management step for a young athlete diagnosed with Hypertrophic Obstructive Cardiomyopathy (HOCM) with left ventricular hypertrophy and normal structure after collapsing during a marathon?

Immediate Disqualification from Competitive Sports and Risk Stratification

This young athlete with HOCM must be immediately and permanently disqualified from competitive athletics, including marathon running, and undergo comprehensive sudden cardiac death risk stratification with consideration for ICD placement. 1

Critical First Steps: Sports Restriction

• Permanent disqualification from all competitive sports is mandatory for athletes diagnosed with HCM, as HCM accounts for approximately one-third of sudden cardiac deaths in young athletes, and intense competitive sports significantly increase this risk. 1

• The collapse during marathon running represents a sentinel event—physical activity during training or competition triggers the vast majority of sudden deaths in athletes with HCM, with a relative risk 2.5 times higher than non-athletes with the same disease. 1

• This recommendation applies specifically to sanctioned high school and college competitive sports and any recreational activities that simulate competitive athletics or involve burst exertion (like marathon running). 1

Immediate Management Algorithm

Step 1: Sudden Cardiac Death Risk Stratification

• All patients with HCM require comprehensive SCD risk assessment using major noninvasive risk markers to identify candidates for ICD placement—this is the highest priority given the collapse during exertion. 1, 2

• Risk factors to evaluate include: family history of sudden cardiac death, unexplained syncope, non-sustained ventricular tachycardia on Holter monitoring, abnormal blood pressure response to exercise, massive left ventricular hypertrophy (≥30mm), and left atrial enlargement. 1

Step 2: Initiate Pharmacologic Therapy

• Start nonvasodilating beta-blockers as first-line therapy, titrated to resting heart rate of 60-65 bpm, regardless of whether the patient has obstructive or non-obstructive HCM. 3, 2

• Beta-blockers reduce LVOT gradients, alleviate dyspnea, improve quality of life, and may reduce arrhythmic risk. 2, 4

• If beta-blockers are ineffective or not tolerated, substitute with non-dihydropyridine calcium channel blockers (verapamil up to 480mg/day or diltiazem), never dihydropyridine types like amlodipine or nifedipine which are Class III: Harm. 3, 2

Step 3: Comprehensive Cardiac Imaging and Follow-up

• Repeat echocardiography is appropriate, but the timing should be based on clinical need for assessing response to therapy and LVOT gradient measurement, not arbitrarily at 3 weeks. 1

• Cardiac MRI should be performed if not already done to assess for fibrosis (late gadolinium enhancement), which is an additional risk marker for sudden death. 1

Step 4: Permitted Physical Activity Counseling

• Low-intensity recreational exercise only: aerobic activities like swimming laps or cycling at moderate pace are preferable to isometric exercise or burst exertion activities. 1

• Avoid all activities that simulate competitive athletics, involve sprinting or burst exertion, or occur in extreme environmental conditions (heat, cold, high humidity). 1

• The statement "exercise after 3 months" is dangerously misleading—competitive sports remain permanently contraindicated, and only carefully selected low-intensity recreational activities are appropriate, with no specific 3-month waiting period required. 1

Critical Pitfalls to Avoid

• Never allow return to competitive sports or marathon running—the collapse during exertion is a red flag that this patient is at high risk, and continued competitive athletics could be fatal. 1

• Do not prescribe vasodilators (ACE inhibitors, ARBs, dihydropyridine calcium channel blockers, nitrates, alpha-blockers) as these worsen LVOT obstruction and can precipitate hemodynamic collapse. 3, 2

• "Advise to eat healthy food" is insufficient—specifically address cardiometabolic risk factors including obesity (present in >70% of HCM patients), hypertension, diabetes, and sleep apnea, as these are associated with worse outcomes. 1, 2

• Avoid aggressive diuresis even if congestive symptoms develop, as decreased preload worsens LVOT obstruction. 3

Additional Considerations

• Screen first-degree relatives with echocardiography and consider genetic testing, as HCM has a prevalence of 1:500 and is inherited in an autosomal dominant pattern. 1

• If symptoms persist despite optimal medical therapy and significant LVOT obstruction (gradient ≥50 mmHg) is present, consider mavacamten (cardiac myosin inhibitor) or referral to a comprehensive HCM center for septal reduction therapy. 3, 2, 5

• Establish anticoagulation if atrial fibrillation develops, as HCM patients have high thromboembolic risk independent of CHA₂DS₂-VASc score. 2