Invasive Cardiac Hemodynamics in Apical Hypertrophic Cardiomyopathy

Abstract

Background: Symptomatic limitations in apical hypertrophic cardiomyopathy may occur because of diastolic dysfunction with resultant elevated left ventricular filling pressures, cardiac output limitation to exercise, pulmonary hypertension (PH), valvular abnormalities, and/or arrhythmias. In this study, the authors aimed to describe invasive cardiac hemodynamics in a cohort of patients with apical hypertrophic cardiomyopathy.

Methods and results: Patients presenting to a comprehensive hypertrophic cardiomyopathy center with apical hypertrophic cardiomyopathy were identified (n=542) and those who underwent invasive hemodynamic catheterization (n=47) were included in the study. Of these, 10 were excluded due to postmyectomy status or incomplete hemodynamic data. The mean age was 56±18 years, 16 (43%) were women, and ejection fraction was preserved (≥50%) in 32 (91%) patients. The most common indication for catheterization was dyspnea (48%) followed by suspected PH (13%), and preheart transplant evaluation (10%). Elevated left ventricular filling pressures at rest or exercise were present in 32 (86%) patients. PH was present in 30 (81%) patients, with 6 (20%) also having right-sided heart failure. Cardiac index was available in 25 (86%) patients with elevated resting filling pressures. Of these, 19 (76%) had reduced cardiac index and all 6 with right-sided heart failure had reduced cardiac index. Resting hemodynamics were normal in 8 of 37 (22%) patients, with 5 during exercise; 3 of 5 (60%) patients had exercise-induced elevation in left ventricular filling pressures.

Conclusions: In patients with apical hypertrophic cardiomyopathy undergoing invasive hemodynamic cardiac catheterization, 86% had elevated left ventricular filling pressures at rest or with exercise, 81% had PH, and 20% of those with PH had concomitant right-sided heart failure.

Keywords: apical hypertrophic cardiomyopathy; diastolic dysfunction; invasive hemodynamics; pulmonary hypertension.

Figure 1. Chart depicting patient selection.

Out of a total of 542 consecutive patients with hypertrophic cardiomyopathy (HCM) presenting to our comprehensive HCM center, 495 patients with eosinophilic myocardits, nonapical HCM, and/or those who did not undergo invasive cardiac hemodynamic catheterization were excluded. The remaining 47 patients were chart reviewed and another 10 patients were excluded due to postmyectomy status or incomplete hemodynamic data. The final study cohort included 37 patients. LAP indicates left atrial pressure; LV, left ventricular; and LVEDP, left ventricular end diastolic pressure.

Figure 2. Distribution of invasive cardiac hemodynamic catheterization data.

Of 37 patients with apical hypertrophic cardiomyopathy (ApHCM) who underwent invasive cardiac hemodynamic assessment at rest, 29 patients had elevated left ventricular (LV) filling pressures defined as pulmonary artery wedge pressure (PAWP) >15 mm Hg and/or LV end‐diastolic pressure >12 mm Hg. Of these, 19 patients had low cardiac index (<2.5 L/min per m²), 6 patients had normal cardiac index (≥2.5 L/min per m²), and 4 did not have cardiac index calculated. Of 8 patients with normal resting LV filling pressures, 5 patients had hemodynamic assessment repeated with exercise, and 3 of these patients had elevated LV filling pressures with exercise (PAWP ≥25 mm Hg). Pulmonary hypertension (defined as mean pulmonary artery pressure >20 mm Hg) was present in 30 of 37 (81%) patients. Of these, 16 patients (53.3%) had postcapillary pulmonary hypertension defined as PAWP >15 mm Hg and pulmonary vascular resistance (PVR) <3 WU, 13 patients (43.3%) had mixed pulmonary hypertension (PAWP >15 mm Hg and PVR ≥3 WU), and 1 patient (3.3%) had precapillary pulmonary hypertension (PAWP ≤15 mm Hg and PVR ≥3 WU).

Figure 3. Impact of cardiac catheterization on clinical management.

Results of cardiac hemodynamic catheterization influenced clinical management in 31 of 37 (84%) cases including assistance with surgical decision (12 of 31 [39%] proceeded to myectomy, 4 of 31 [13%] deferred myectomy), change in medical management (8 of 31 [26%] adjusted heart failure with preserved ejection fraction [HFpEF] management and 4 of 31 [13%] adjusted pulmonary hypertension [PH] therapy), and decision to proceed with heart transplant evaluation (3 of 31 [10%]). Cardiac hemodynamic catheterization was performed as part of preheart transplant evaluation in 3 of 37 (8%) patients and did not change clinical management in 3 of 37 (8%) patients.