20-year prognosis of hypertrophic cardiomyopathy: low mortality but high morbidity

In a community-based cohort study on hypertrophic cardiomyopathy (HCM), few patients died each year of the disease but HCM-related morbidity was substantial.

Introduction and methods

Background

Hypertrophic cardiomyopathy (HCM) is a slowly progressive disorder in which clinical features can develop throughout life [1,2]. Recent studies have suggested that the prognosis has improved and HCM is generally associated with mild disability and normal life expectancy, if sudden death can be prevented [3-6].However, the follow-up period of most studies on clinical outcomes of HCM was less than 10 years [7,8].

Aim of the study

The authors aimed to determine the clinical course of HCM over a follow-up period of approximately 20 years.

Methods

In this retrospective, single-center, longitudinal study, complete and detailed clinical records of 93 consecutive patients were analyzed who had been diagnosed with HCM at the Kochi Medical School Hospital in Kochi, Japan by 31 December 2000.

Based on morphologic and hemodynamic assessments by echocardiography, patients were divided into 5 groups:

1. hypertrophic obstructive cardiomyopathy (HOCM), defined as presence of basal LV outflow tract obstruction (gradient: >30 mmHg);

2. mid-ventricular obstruction (MVO), defined as presence of systolic LV cavity obliteration at mid ventricle, creating MVO with peak systolic gradient >30 mmHg;

3. end-stage HCM, defined as LV systolic dysfunction of global EF <50%;

4. apical HCM, defined as hypertrophy confined to LV apex below papillary muscle level;

5. hypertrophic non-obstructive cardiomyopathy (HNCM) (i.e., non-obstructive HCM other than end-stage HCM or apical HCM).

Outcomes

The occurrence of HCM-related death and HCM-related adverse events were evaluated.

Main results

Baseline patient characteristics

• Mean ± SD age at the initial evaluation was 51.5 ± 13.0 years. Of the 93 patients, 63 (68%) were male.
• At the initial evaluation, 11 patients (12%) had documented paroxysmal or permanent AF.
• There were 7 patients (8%) in the HOCM group, 3 (3%) in the MVO group, 7 (8%) in the end-stage HCM group, 18 (19%) in the apical HCM group, and 58 (62%) in the HNCM group.
• At baseline, all patients in the HOCM and MVO groups demonstrated NYHA class I or II HF symptoms.

Hypertrophic cardiomyopathy-related deaths

• During a mean follow-up duration of 19.6 ± 8.1 years (median: 20.1 years), 47 patients (51%) died.
• HCM-related deaths occurred in 20/93 patients (21%): sudden cardiac death (SCD) in 5 patients, HF death in 11 patients, and embolic stroke death in 4 patients.
• The annual HCM-related mortality rate was 1.1%, and the HCM-related 20-year survival rate was 81%.
• Mean age at HCM-related death was 70.7 ± 9.1 years (range: 49–84).
• Patients with HCM-related death were older at initial evaluation than those without HCM-related death (57.8 ± 10.0 vs. 49.7 ± 13.3 years; P=0.005) and had a higher rate of AF symptoms at initial evaluation (40% vs. 4%; P<0.001).

Hypertrophic cardiomyopathy-related adverse events

• During follow-up, a total of 69 HCM-related adverse events occurred in 45 patients (48%): SCD-relevant events (including SCD and spontaneous sustained ventricular tachycardia with haemodynamic instability or discharges of ICD) in 16 patients, composite HF events (including HF death and HF hospitalization) in 33 patients, and composite embolic stroke events (including embolic stroke deaths and hospitalization for embolic stroke) in 20 patients. In 22 patients, multiple events occurred.
• The first HCM-related adverse event occurred in approximately 20% of the patients in the first decade since the initial evaluation. In both the second and third decades, the first HCM-related adverse event was also observed in about 20% of the patients.
• Patients with HCM-related adverse events in the first 10 years had a worse clinical profile than those without HCM-related adverse events. They were significantly older at baseline, experienced more symptoms, had a higher rate of AF (33% vs. 2%; P=0.002), and showed more advanced LV and left atrial remodeling.
• After the first decade, there were no statistically significant differences in the clinical profiles between patients with and without HCM-related events.

Atrial fibrillation and left ventricular remodeling

• During follow-up, 36 patients (39%) developed new-onset AF, which meant that at the last follow-up visit, 47 patients (51%) in total had documentation of AF.
• During the study, 22 patients (24%) progressed to end-stage HCM, resulting in a total of 29 patients (31%) with this diagnosis at the end of follow-up.

Conclusion

References

Find this article online at ESC Heart Fail.