Exercise unmasks impaired vascular and cardiac hemodynamic in patients with hypertrophic cardiomyopathy

Background/Introduction

Exertional dyspnea is a common finding in patients with Hypertrophic Cardiomyopathy (HCM), yet little data is available regarding the hemodynamic disturbances that lead to symptom development in this population.

Purpose

To investigate the mechanisms involved in the functional limitation of patients with HCM.

Methods

We prospectively studied 20 symptomatic patients with confirmed diagnosis of HCM. Assessment included NT-pro BNP levels, echocardiogram, and invasive characterization, where subjects also underwent invasive cardiopulmonary exercise testing.

Results

Median patient age was 57 (48–66) years old and 15 (75%) were male. Basal NT-pro BNP was elevated (748 pg/mL [406–1082]) and 8 (40%) subjects had NYHA functional Class III despite optimal medical treatment. Sarcomeric abnormal mutations were identified in 12 subjects (60%), most frequently in MYBPC3. Ultrasound imaging showed marked left ventricle (LV) hypertrophy (LV Mass Index 140 g/m2 [109–161]), with signs of LV outflow obstruction in 13 (65%) subjects. All patients displayed preserved ejection fraction (68% [61–73]). Significant mitral regurgitation was present in 5 subjects and median E/e' was 9.87 [6.43–13.14].

At rest, biventricular filling pressures were relatively normal, with upper limit mean Pulmonary Pressure (Table). Patients exercised for 6.4 (95% CI: 5.6–7.2) min, achieving a respiratory exchange ratio of 1.11 (1.02–1.17). All subjects displayed normal cardiac output at rest (5.6 L/min (3.7–7.5)), that increased during exertion, due mostly to a rise in heart rate (p<0.0001). Exercise doubled LV End-Diastolic Pressure from 15.3 (11.5–19.1) mmHg at baseline to 30.4 (26.6–34.3) mmHg at peak VO2 (p<0.0001), whereas mean pulmonary pressure increased from 21 (14–29) mmHg to 40 (33–47) mmHg (p<0.0001).

Remarkably, although arterial hemodynamics were relatively normal at baseline, exercise induced significant increases both in the continuous (systemic vascular resistance) and pulsatile components of vascular load (Impedances, p<0.05; Table 1) (Figure 1). This increase in afterload during exertion has not been previously documented in HCM. The decreased compliance derived, can also play a role in the elevated filling pressures documented on exertion.

Conclusion

Exercise unmasks adverse hemodynamics in HCM, severely increasing LV filling pressures and showing systemic arterial dysfunction.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III, Spain.

Pulmonary hypertension and congenital heart disease: medical treatment and risk factors for survival

Background

Pulmonary arterial hypertension (PAH) is a common comorbidity in congenital heart disease (CHD) and significantly affects prognosis. There are four large clinical groups of CHD-related PAH: Eisenmenger syndrome, PAH associated with non-restrictive shunt, PAH associated with restrictive shunt and postoperative PAH. Our purpose was to study the clinical and prognostic differences among them.

Methods

The REHAP is a Spanish multicentre voluntary registry of patients over 14 years of age, which includes patients with CHD and PAH, starting in 2007. 664 patients were analyzed: Baseline characteristics, functional class, right catheterization data, treatment and survival were compared.

Results

664 patients were analyzed: characteristics are detailed in the table. Patients with Eisenmenger were more frequently treated with oral monotherapy as a first line therapy and received less frequently prostanoids during the follow-up. Patients with Eisenmenger had significantly better prognosis, with the best long-term survival of the 4 groups. In a cox regression model, postoperative PAH has a 1.7 hazard ratio (HR) (reference group: Eisenmenger) after adjustment for age (HR 1.02 p 0,001), functional class (HR NYHA III-IV 2.3 p<0,001), sex (p 0.8) and pulmonary vascular resistance (p 0.7).

Conclusion

The clinical classification of PAH associated with CHD defines both the baseline characteristics and the prognosis of patients. Outcome relates closely to functional class and type of PAH–CHD. Eisenmenger group, which has the most severe hemodynamics, is the one with the best prognosis despite a less aggressive treatment.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Ferrer, Janssen