Associazione Nazionale Medici Cardiologi Ospedalieri



The impact of Disopyramide on exercise capacity in Hypertrophic Cardiomyopathy: it is not all about relieving obstruction.

Dei Lorenzo-Lupo L’Aquila(Abruzzo) – Università degli Studi de L’Aquila | Ciacci Paolo Roma(Lazio) – Università Campus Biomedico di Roma | Giacalone Guido Roma(Lazio) – Università Sant’Andrea


Disopyramide has been extensively utilized since the late 1980s to decrease obstruction and improve symptoms in patients with obstructive hypertrophic cardiomyopathy (oHCM). Nevertheless, there is currently no evidence about the impact of this drug on functional capacity assessed with cardiopulmonary exercise test (CPET).


To investigate the impact of disopyramide on functional capacity and peak exercise gradient, assessed by CPET combined with stress echocardiography (Imaging-CPET).


21 disopyramide-treated oHCM patients were studied with Imaging CPET before and after 3 months of treatment starting at the cardiomyopathy unit of San Camillo Forlanini Hospital (Rome).

After a baseline echocardiography, symptoms limited CPET was done on an upright bicycle ergometer utilizing a 10 Watt/min. ramp protocol.

Cardiopulmonary variables were measured with breath-by-breath analysis.

During CPET, Doppler Echocardiography was performed. LVOT velocities and trans-valvular gradient and diastolic function were taken at peak exercise and during recovery.


21 patients (mean age 48.3 years; 57% male; average daily-dose 450 mg) were evaluated.

Of those, 96% were taking concurrent b-blocker medication, whereas 4% were receiving a calcium antagonist.

After 3 months of disopyramide, mean resting outflow gradient decreased from 40 to 29 mmHg (p =0.08) and from 63 to 41mmHg (p=0.014) at peak exercise. There was no notable reduction in EF (p=0.9) or improvement in diastolic function at rest (p=0.1) or at peak exercise (p=0.7).

Mean heart rate significantly decreased both at rest (78 vs 68 bpm; p=0.02) and peak exercise (131 vs 113 bpm; p=0.001), along with a decrease in chronotropic response (predicted HR = 81% vs 70%; p=0.001).

Furthermore, after treatment, mean functional capacity decreased significantly (20ml/kg/min vs 17ml/kg/min; p=0.02;) whereas neither VE/VCO2 (p=0.5) nor oxygen pulse(p=0.9) changed considerably.

19 patients (90%) reported improved quality of life despite no increase in NYHA class.


This study, for the first time, showed that although disopyramide decreases the exercise gradient, it does not improve functional capacity since it significantly alters the chronotropic response.

These findings emphasize the value of heart rate response evaluation in patients with HCM and the importance of carefully adjusting the dose of negative chronotropic agents.