Dr. Albert A. Hagege, Hopital Europeen G. Pompidou, reviewed studies of atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM). The prevalence of AF in patients with HCM ranges from 10-22%. The incidence of embolic events in non-selected patients with HCM is 0.8% annually. Multivariate analysis showed that the main risk factors for AF in HCM patients were age >50 years (OR=2.3, p<0.001), NYHA class III/IV (OR=2.8, p<0.005), and left atrial (LA) dimension ≥45 mm (OR=3.4, p<0.0001). More than 30% of patients with LA >45 mm and NYHA class II-IV develop AF by 6 years (p<0.0001). P wave duration ≥140 ms plus LA >40 mm also predicts AF in HCM patients.

Figure 1. Prognostic impact of atrial fibrillation. 【Click to enlarge】

Figure 2. Morbidity and mortality associated with atrial fibrillation. 【Click to enlarge】

HCM patients with AF have a higher risk for CV death (OR=3.7) and stroke (OR=8.3) than the general population and patients with heart failure (HF) (Figure 1). AF can lead to pulmonary edema/ischemia, syncope, and sudden death in the acute setting and to functional impairment, thromboembolic events, and death in the chronic setting (Figure 2). HCM patients with AF have higher risk of mortality (p<0.0001) and cumulative risk of embolism (p<0.0001) than those with SR. The probability of HCM-related adverse outcomes is higher with chronic versus paroxysmal AF (p<0.0001).

More HCM patients with vascular events have NYHA class III/IV (p<0.005), history of AF (p<0.001), LA dimension ≥45 ms (p<0.001), and age >60 years (p<0.01). HCM patients with AF and outflow obstruction have a higher risk of death than those with AF without obstruction (p<0.0001). Patients ≤50 years with AF have higher rates of mortality (p<0.001), stroke (p<0.0001), and progression to NYHA III/IV (p<0.0001) than those >50 years.

Patients with HCM and AF are treated with anticoagulation and rate control or rhythm control therapies. Olivotto showed that HCM patients with chronic AF over time had a higher probability of CV death, embolism, and/or progression to NYHA class III/IV versus those maintained in SR (p<0.001).

AF is the most common sustained arrhythmia in patients with HCM. The main risk factors are LA dilatation, advanced age, and NYHA class. AF is associated with disease progression, a 4-fold increase in mortality, and 8-fold increase in embolic events. Early onset and obstruction markedly increase the risk of adverse outcomes. Maintenance of SR is associated with better outcomes. Long-term anticoagulation is necessary once paroxysmal or chronic AF occurs. As stroke may be the first manifestation of AF, progressive LA dilatation is an indication for repeat Holter ECG and consideration of anticoagulation.

Dr. Makoto Okawa, Kochi Medical School, discussed data from his studies on the natural history and clinical course of hypertrophic cardiomyopathy (HCM). A study of the long-term clinical course of HCM in rural Japan (N=137) reported 5-, 10-, and 15-year survival of 91%, 88%, and 79%, respectively. Of 28 HCM-related deaths, 10 were caused by heart failure (HF).

Tissue doppler imaging (TDI) was used to assess 156 patients with HCM in sinus rhythm (SR). Elevated LV filling pressure was defined as E/e’ ≥15. Decreased left atrial (LA) filling was defined as a’ ≤8. During 3.3 years mean follow-up, cardiac events (HF hospitalization, death) occurred n 13 patients. Diastolic HF associated with atrial fibrillation (AF) was common (N=6). Cardiac events occurred more frequently in patients with E/e’ ≥15 (p=0.001) or a’ ≤8 (p=0.002). AF occurred in 31% of patients with a’ ≤8 and in 10% of those with a’ >8. Multivariate analysis showed that both E/e’ ≥15 (HR=3.74, p=0.025) and a’ ≤8 (HR=3.64, p=0.032) were independent predictors of cardiac events.

HCM patients (N=59) in SR were evaluated to determine if the Doppler-derived Tei index (assessment of total myocardial performance) is predictive of future ventricular remodeling. Ventricular remodeling was defined as an increase in LV dimension ≥5 mm and decrease in maximum wall thickness (MWT) ≥5 mm. Significantly more patients with a Tei index ≥0.58 developed ventricular remodeling versus patients with Tei index <0.58 (p<0.02).

Echocardiographic features of 13 end-stage HCM patients were evaluated, focusing on wall motion abnormalities. Patients with mild LV remodeling had preserved septal hypertrophy and reduced septal wall motion. Patients with advanced LV remodeling had septal wall thinning and cavity enlargement but relatively maintained posterolateral wall motion.

The prognosis of patients with dilated phase HCM (D-HCM) (N=20) and DCM (N=115) was compared in a recent study. Patients with D-HCM had more severe HF symptoms and poorer prognosis than those with DCM. Kaplan-Meier analysis showed that 5-year survival rates were significantly lower in patients with D-HCM (45.6%) versus those with DCM (81.6%) (p=0.0001). Intensive treatment strategies including implantable cardioverter defibrillator (ICD) and cardiac resyndhronization therapy (CRT), or ultimately heart transplantation, might be necessary for patients with end-stage HCM.

Assessment of LV diastolic and systolic function, LA function, and ventricular remodeling is clinically important in the management of patients with HCM. Early identification and intensive treatment of ventricular remodeling are warranted, considering the unfavorable course of end-stage HCM.