AJC: Be aware of asymptomatic hypertrophic cardiomyopathy

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Patients diagnosed with hypertrophic cardiomyopathy (HC), either incidentally or nonincidentally, and who are diagnosed symptomatically and have a family history of HC have an almost five-fold risk of cardiovascular death, according to a study published May 15 in the American Journal of Cardiology.

“HC is probably the most heterogeneous disease in clinical cardiology, in terms of phenotypic presentation, symptoms, and outcome,” the authors wrote. However, there are a large cohort of patients who remain asymptomatic and, often, these patients are diagnosed incidentally during a routine medical exam.

Georgios K. Efthimiadis, MD, from the Aristotle University of Thessaloniki in Greece, and colleagues evaluated 380 patients to investigate the incidence of patients who were incidentally diagnosed with HC.

During the trial, researchers split patients into two groups: 111 asymptomatic patients incidentally diagnosed from routine exam—precordial murmur and/or abnormal electrocardiographic findings—and 269 symptomatic patients who were diagnosed due to a family history of HC.

Between February 1992 and March 2008, researchers performed a retrospective, observational study of HC patients whose condition was determined by echocardiographic appearance or a left ventricular maximum wall thickness of greater than or equal to 15 mm.

Patients had a mean age of 49.3, 65 percent were men and the mean follow-up period of the trial was 58 months.

Patients were evaluated every 12 months via a clinical evaluation, a 12-lead EKG, a transthoracic echo, 24-hour EKG monitoring and an exercise stress test.

The researchers used mortality rates including overall cardiovascular mortality and sudden death as primary endpoints.

Results showed that 65.8 percent of patients who were incidentally diagnosed were graded as NYHA class I, compared to only 33.1 percent of the nonincidentally diagnosed patients.

After a 58-month follow-up, overall results showed that 23 patients died. During the study, the five-year survival rate from CV death was 97.6 percent—seven patients suffered sudden death, three patients from ventricular tachycardia, four patients had implantable cardioverter-defibrillator discharge and five patients suffered resuscitated cardiac arrest.

“Overall mortality did not differ between the two groups,” the authors wrote. “However, the patients diagnosed because of either symptoms or family history tended to have at least a 4.5-fold greater risk of CV death.”

Additionally, patients who were nonincidentally diagnosed had a 4.3 greater risk of sudden death and 8.2 percent of the nonincidentally diagnosed group and 2.7 percent of the incidentally diagnosed group reached end-stage HC.

“Our results have corroborated that most patients with HC continue to be diagnosed largely owing to symptom development or on the basis of a systematic pedigree evaluation for families with a positive disease history,” the authors wrote.

While rates of mortality between the two cohorts were similar, sudden death occurred more frequently in the asymptomatic patient cohort, but cardiovascular mortality was greater in nonincidentally diagnosed patients.

“The discrepancy between the low numbers of patients reported by published registries and the relatively high prevalence of the disease in the general population can be attributed to the large number of patients who remain asymptomatic, even throughout their life, awaiting an accidental diagnosis,” the authors concluded. “A high level of awareness and suspicion for HC among physicians is essential for clinical recognition of such patients."