Cardiac Involvement in Muscular Dystrophy: A Medical-Legal Guide for Attorneys

A 15-year-old boy with Duchenne muscular dystrophy (DMD) has been followed for years by neurology and pulmonology. He uses a power wheelchair and is no longer ambulatory. His last echocardiogram was at age 9; because he never complained of chest pain or shortness of breath, no further cardiac imaging was obtained, and no cardiac medication was ever started. He is admitted for elective scoliosis surgery without a pre-operative cardiac evaluation. During the procedure he develops refractory heart failure and dies. Autopsy reveals a severely dilated, fibrotic left ventricle — a cardiomyopathy that had been progressing silently for years.

This hypothetical illustrates the central medical-legal problem in muscular dystrophy: the heart disease is frequently advanced before it produces any symptom the patient can report, because the skeletal-muscle disability that defines these disorders also removes the exertional demands that normally unmask heart failure. As survival from respiratory causes has improved, cardiac disease has become a leading cause of death in several muscular dystrophies — and, correspondingly, a growing focus of litigation. This article provides an objective, evidence-based overview to help attorneys understand where liability is alleged, how causation is analyzed, and what legitimate defenses exist.

Why Cardiac Involvement in Muscular Dystrophy Is a Distinct Medical-Legal Problem

The muscular dystrophies are inherited disorders of skeletal and cardiac muscle. From a cardiac standpoint, they fall into two broad and clinically critical categories — a distinction that drives nearly every standard-of-care question:

• Cardiomyopathy-predominant dystrophies, in which a dilated cardiomyopathy is the main cardiac threat. These include Duchenne (DMD), Becker (BMD), and limb-girdle types 2C, 2D, 2E, 2F, and 2I (Silvestri et al., Muscle & Nerve, 2018; Al-Khatib et al., 2017 AHA/ACC/HRS Guideline).
• Conduction-predominant dystrophies, in which degeneration of the heart's electrical (conduction) system, heart block, and sudden death are the main threats, with cardiomyopathy variable. These include myotonic dystrophy types 1 and 2, Emery-Dreifuss muscular dystrophy, and limb-girdle type 1B (lamin A/C) (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline; Glikson et al., 2021 ESC Pacing Guidelines).

Two features make these cases distinctive. First, cardiac disease is often silent: in DMD, myocardial scarring (fibrosis) and falling heart function develop before any symptoms, and a non-ambulatory patient cannot generate the exertion that would normally reveal heart failure (Feingold et al., Circulation, 2017; Kamdar & Garry, Journal of the American College of Cardiology, 2016). Second, the standards for surveillance and treatment are unusually explicit and society-endorsed, which makes deviations comparatively easy to identify. Because the two categories require fundamentally different monitoring, applying the wrong framework to a given diagnosis is itself a recurring standard-of-care error.

The Standard of Care: Surveillance

The surveillance schedules are the most concrete standards in this area because they are specified by professional societies.

For Duchenne and Becker muscular dystrophy, the American Heart Association's 2017 scientific statement recommends:

• An initial cardiac evaluation — examination, electrocardiogram (ECG), and imaging — at the time of diagnosis (Feingold et al., Circulation, 2017).
• Evaluation every two years in asymptomatic patients under age 10, increasing to at least annually beginning at age 10, because the risk of left-ventricular dysfunction rises steeply with age — from under 5% in boys younger than 10 to more than 75% in men older than 20 (Feingold et al., Circulation, 2017).
• More frequent evaluation once symptoms appear or abnormalities are first detected on imaging (Feingold et al., Circulation, 2017).
• Cardiac evaluation of female carriers in the second-to-third decade of life, with follow-up every three to five years, because carriers can develop reduced heart function and myocardial fibrosis (Feingold et al., Circulation, 2017).

The 2018 DMD Care Considerations, published in Lancet Neurology, reinforce these schedules and add two litigation-relevant points: cardiac MRI (CMR) is the preferred imaging modality once a child can cooperate (typically around age 6–7), because it detects fibrosis earlier than echocardiography; and an ECG and cardiac imaging should be obtained before major surgery such as scoliosis correction (Birnkrant et al., Lancet Neurology, 2018). The American Academy of Pediatrics' companion guidance goes further, recommending that yearly cardiac screening begin at diagnosis, reflecting growing recognition that adverse myocardial changes occur earlier than previously believed (Buddhe et al., Pediatrics, 2018).

A crucial evidentiary theme is that normal symptoms and even a normal echocardiogram do not exclude significant disease. In DMD, heart dysfunction precedes chamber dilation, the average age of a first abnormal ejection fraction is roughly 14 years, and fibrosis is often visible on CMR before echocardiographic or ECG changes appear (Feingold et al., Circulation, 2017; Kamdar & Garry, Journal of the American College of Cardiology, 2016). Reliance on symptoms alone, or on echocardiography in a patient with poor imaging windows from scoliosis and respiratory disease, is a recurring vulnerability.

For the conduction-predominant dystrophies, surveillance is directed at the electrical system. In myotonic dystrophy, professional guidelines advise at least annual ECG, and often ambulatory (Holter) monitoring, even during the asymptomatic "concealed" phase, because conduction disease progresses unpredictably and can cause sudden death (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline; Zeppenfeld et al., 2022 ESC Guidelines). For Emery-Dreifuss and limb-girdle type 1B (lamin A/C), a 12-lead ECG and echocardiogram are important at initial assessment regardless of symptoms, with ongoing rhythm monitoring (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline).

The Standard of Care: Treatment

Because there is no dystrophin-specific cardiac drug, the standard is conventional heart-failure therapy, applied on a disease-appropriate timeline.

Early / prophylactic ACE-inhibitor therapy in DMD

A randomized trial (Duboc et al.) and subsequent registry analyses found that starting an ACE inhibitor before measurable dysfunction — as boys approach age 10 — delayed the onset of left-ventricular dysfunction and was associated with improved survival, and the 2014 NHLBI working group recommended ACE inhibitors or ARBs by age 10 (Birnkrant et al., Lancet Neurology, 2018; McNally et al., Circulation, 2015). A Cochrane review characterizes the certainty of this evidence as low, and opinion differs on treating very young asymptomatic boys with normal imaging (Bourke et al., Cochrane Database of Systematic Reviews, 2018).

Treatment once dysfunction or fibrosis appears

Irrespective of age, therapy should begin with the onset of heart-failure symptoms or when abnormalities such as reduced ejection fraction, abnormal chamber size, or myocardial fibrosis are seen on imaging. Beta-blockers are typically added with ventricular dysfunction, and the mineralocorticoid antagonist eplerenone has been shown in a randomized trial to attenuate the decline in cardiac function (Birnkrant et al., Lancet Neurology, 2018; Bourke et al., Cochrane Database of Systematic Reviews, 2018).

Device therapy and advanced options

In the conduction-predominant dystrophies, guidelines set specific thresholds — for example, pacemaker implantation for advanced heart block, and a low threshold for an implantable cardioverter-defibrillator (ICD) in lamin A/C disease, where sudden death accounts for roughly one-third of deaths and ICDs can be appropriate even with preserved ejection fraction (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline; Zeppenfeld et al., 2022 ESC Guidelines). In DMD/BMD, ICDs and advanced therapies (including transplant in selected BMD patients) follow non-ischemic cardiomyopathy standards, tempered by overall prognosis (Zeppenfeld et al., 2022 ESC Guidelines).

Common Targets of Litigation (Plaintiff Perspective)

• Failure to perform baseline and surveillance cardiac testing. Not obtaining an evaluation at diagnosis, or not escalating to annual imaging at age 10 in DMD/BMD, is the most concrete allegation because the schedule is explicit (Feingold et al., Circulation, 2017; Buddhe et al., Pediatrics, 2018).
• Failure to obtain pre-operative cardiac evaluation before scoliosis surgery or other major procedures, as specifically called for in the DMD Care Considerations (Birnkrant et al., Lancet Neurology, 2018).
• Over-reliance on symptoms or a single normal study, given that fibrosis and dysfunction accumulate silently and may be missed by echocardiography (Kamdar & Garry, Journal of the American College of Cardiology, 2016).
• Failure to initiate or escalate guideline-directed therapy — for example, not starting an ACE inhibitor/ARB when dysfunction or fibrosis first appears, or not adding beta-blockade or a mineralocorticoid antagonist as disease progresses (Birnkrant et al., Lancet Neurology, 2018).
• Applying the wrong surveillance model to the diagnosis — monitoring a conduction-predominant dystrophy (myotonic dystrophy, Emery-Dreifuss, LGMD1B) as though it were a cardiomyopathy problem, and thereby missing progressive heart block and sudden-death risk (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline).
• Failure to recognize conduction disease and prevent sudden death — not acting on a lengthening PR interval or widening QRS, or not referring for pacemaker/ICD evaluation when indicated (Zeppenfeld et al., 2022 ESC Guidelines).
• Failure to refer to a cardiologist / delayed referral. The DMD Care Considerations note that patients historically have not been referred to a cardiac specialist until late in the disease, contributing to poor outcomes, and that heart-failure signs in non-ambulatory patients are frequently subtle and overlooked (Birnkrant et al., Lancet Neurology, 2018).
• Failure to screen and counsel female carriers, who are themselves at risk of cardiomyopathy (Feingold et al., Circulation, 2017).

Common Defense Themes

A balanced evaluation requires equal attention to legitimate defenses, several of which are grounded in the same literature:

• Relentless natural history. Dystrophin-deficient cardiomyopathy is progressive and, to date, incurable; there is no dystrophin-specific cardiac therapy. A defensible position in many cases is that guideline-concordant care delays but does not prevent cardiac decline, so some deterioration was unavoidable regardless of management (Kamdar & Garry, Journal of the American College of Cardiology, 2016; Birnkrant et al., Lancet Neurology, 2018).
• Limited and low-certainty evidence for prevention. The Cochrane review found only low- to very-low-certainty evidence that early ACE inhibitors, ARBs, or eplerenone modify the disease course, and no adequately powered long-term trials; the trials were small and used surrogate endpoints (Bourke et al., Cochrane Database of Systematic Reviews, 2018). This undercuts claims that a specific earlier medication would, more probably than not, have changed the outcome.
• Genuine areas of clinical judgment and controversy. Guidelines expressly leave certain decisions to the treating cardiologist — for example, whether to start an ACE inhibitor in a very young asymptomatic boy with normal imaging is a matter on which "opinion differs" (Birnkrant et al., Lancet Neurology, 2018). Discretionary decisions within an accepted range are difficult to characterize as departures from the standard of care.
• Prognostic balancing of interventions. For interventions such as ICDs in DMD, guidelines themselves direct that the benefit be weighed against the patient's overall prognosis — so a decision to defer an aggressive intervention may reflect appropriate, guideline-endorsed judgment rather than negligence (Zeppenfeld et al., 2022 ESC Guidelines).
• Inherent limits of testing. Echocardiography is genuinely limited by scoliosis, contractures, and respiratory dysfunction; a "missed" finding may reflect the recognized technical ceiling of the available modality rather than substandard interpretation (Kamdar & Garry, Journal of the American College of Cardiology, 2016).
• Causation and preventability. Even where a lapse in surveillance or therapy is conceded, the defense can contest whether earlier detection or treatment would have altered the trajectory, given the disease's natural history and the low-certainty prevention evidence.

How Causation Is Analyzed

The central causation question mirrors other pediatric malpractice contexts: would guideline-concordant surveillance and earlier therapy, more likely than not, have delayed dysfunction, prevented sudden death, or otherwise changed the outcome? Several evidence-based anchors frame the analysis:

• Evidence that earlier ACE inhibition improves outcomes, and the principle that therapeutic intervention before symptom onset has greater impact, supports plaintiff preventability arguments (Feingold et al., Circulation, 2017; McNally et al., Circulation, 2015).
• The progressive, incurable natural history of the cardiomyopathy and the low certainty of the prevention data support defense arguments that decline was unavoidable (Bourke et al., Cochrane Database of Systematic Reviews, 2018; Kamdar & Garry, Journal of the American College of Cardiology, 2016).
• In conduction-predominant disease, sudden death can result from unpredictable, rapid progression of heart block, which cuts both ways: it strengthens the argument for aggressive rhythm surveillance and pacing, but also supports the position that some sudden deaths occur despite appropriate care (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline).

Causation analysis is therefore highly diagnosis-specific and depends on the exact timeline of testing, findings, and therapy documented in the record.

Common Misconceptions

• "No cardiac symptoms means no significant heart disease." False. Cardiomyopathy in DMD progresses silently, and a non-ambulatory patient may never generate the exertion that reveals heart failure (Feingold et al., Circulation, 2017).
• "A normal echocardiogram rules out cardiomyopathy." False. Fibrosis is frequently detectable on cardiac MRI before echocardiographic or ECG abnormalities, and echocardiography is technically limited in these patients (Kamdar & Garry, Journal of the American College of Cardiology, 2016).
• "All muscular dystrophies need the same cardiac monitoring." False. Cardiomyopathy-predominant and conduction-predominant dystrophies require different surveillance and carry different risks (Al-Khatib et al., 2017 AHA/ACC/HRS Guideline).
• "Female carriers have no cardiac risk." False. Carriers can develop reduced ejection fraction and myocardial fibrosis and warrant their own surveillance (Feingold et al., Circulation, 2017).
• "Any cardiac death in muscular dystrophy proves negligence." False. These cardiomyopathies are progressive and incurable, and death can occur despite fully guideline-concordant care.

Medical Records That Often Matter

• The specific genetic/molecular diagnosis and subtype, which determines the applicable surveillance framework
• Serial ECGs (with attention to PR interval and QRS duration trends), and Holter/ambulatory monitoring
• Echocardiography and cardiac MRI reports, including ejection fraction, chamber dimensions, and late gadolinium enhancement (fibrosis)
• Documentation of surveillance intervals against the age-based schedule
• Pre-operative cardiac evaluation before scoliosis or other major surgery
• Cardiology referral and consultation records, and timing of referral
• Medication records — timing of ACE inhibitor/ARB, beta-blocker, and mineralocorticoid antagonist initiation relative to first abnormal findings
• Device evaluation records — pacemaker/ICD consideration where indicated
• Carrier counseling and screening documentation for at-risk female relatives

Long-Term Outcomes and Damages

Damages depend on the injury. Progressive heart failure may involve escalating medical therapy, hospitalization, advanced device or transplant care, and reduced life expectancy. Sudden cardiac death — the dominant risk in conduction-predominant dystrophies and a recognized risk in lamin A/C disease — gives rise to wrongful-death claims. Because these are chronic, life-limiting diseases, damages analysis must account for the patient's baseline prognosis independent of any alleged negligence.

The Value of Subspecialty Expertise

Evaluating these cases requires expertise spanning pediatric and adult cardiology, electrophysiology, and neuromuscular disease. An experienced expert can identify the correct surveillance framework for the specific diagnosis, interpret ECG, echocardiographic, and CMR findings, assess whether therapy was initiated at the appropriate time, distinguish avoidable from unavoidable outcomes given the natural history, and explain why a normal symptom profile or single normal study does not exclude significant disease. Given how sharply the standards differ by subtype, and how nuanced the causation questions are, subspecialty input is often decisive to accurate case evaluation for either side.

Key Takeaways for Attorneys

• Muscular dystrophies split into cardiomyopathy-predominant (DMD, BMD, several LGMDs) and conduction/sudden-death-predominant (myotonic dystrophy, Emery-Dreifuss, LGMD1B) types requiring different cardiac monitoring.
• Cardiac disease is frequently silent; absence of symptoms and even a normal echocardiogram do not exclude significant disease.
• The surveillance schedules are explicit — baseline evaluation at diagnosis and at least annual assessment from age 10 in DMD/BMD — making deviations comparatively identifiable.
• Pre-operative cardiac evaluation before scoliosis surgery is a specifically recommended step.
• Guideline-directed therapy (ACE inhibitor/ARB, beta-blocker, mineralocorticoid antagonist; device therapy where indicated) and its timing relative to first abnormal findings are central to case review.
• In conduction-predominant dystrophies, watch for failure to monitor for and act on progressive heart block and sudden-death risk.
• Female carriers carry cardiac risk and warrant their own surveillance and counseling.
• Legitimate defenses rest on the progressive, incurable natural history and the low-certainty evidence for prevention — decline may be unavoidable and specific interventions may not have changed the outcome.
• Several decisions fall within recognized clinical judgment, and guidelines direct that some interventions be balanced against overall prognosis.
• Diagnosis-specific subspecialty expertise is essential to distinguish preventable injury from the natural course of the disease.

References

• Silvestri et al., Muscle & Nerve, 2018.
• Al-Khatib et al., 2017 AHA/ACC/HRS Guideline.
• Glikson et al., 2021 ESC Pacing Guidelines.
• Feingold et al., Circulation, 2017.
• Kamdar & Garry, Journal of the American College of Cardiology, 2016.
• Birnkrant et al., Lancet Neurology, 2018.
• Buddhe et al., Pediatrics, 2018.
• Duboc et al., randomized trial.
• McNally et al., Circulation, 2015.
• Bourke et al., Cochrane Database of Systematic Reviews, 2018.
• Zeppenfeld et al., 2022 ESC Guidelines.