Symptoms trend in patients with obstructive hypertrophic cardiomyopathy treated with disopyramide

Abstract Background In obstructive hypertrophic cardiomyopathy (HOCM) medical intervention becomes necessary when symptoms coexist, whereas invasive septal reduction therapy (SRT) is indicated in presence of NYHA class >II, although optimized medical therapy. Thus, if SRT is avoided by medical therapy patient should be considered responder. However, due to inconsistency on definition of responders, effectiveness of medical therapy among data are conflicting. In addition, only short follow-up (FU) is available for analyses. Purpose To address this, we conducted a retrospective analysis in two HCM centers, both defining responders based on guidelines recommendations. Methods 62 symptomatic HOCM patients (43% women, age 52±14 years) with LVOTG ≥50 mmHg at rest or during provocation, were recruited from two HCM Italian centers. Disopyramide was added as second-line therapy. Responders were those reaching at least NYHA class II, if >II at baseline and those reaching NYHA class I or with stabilization of symptoms if in NYHA II class at baseline. Results At FU, (mean 4.4 years, IQR 1.1-6.6 years), 47 patients (76%) were responders, whereas 15(24%) patients were no-responders. Changes in NYHA class from baseline to follow-up are reported in the Figure. There were no differences at baseline of clinical and echocardiographic data between responders and no-responders, whereas at FU responders showed a significant lower LVOTG than no-responders (43 ±32 vs 66 ±28 mmHg, respectively, p=0.013), with LVOTG <50 mmHg more represented in responders than in no-responders (75% vs 25%, respectively; p=0.004) (Figure). No side effects indicating discontinuation of the therapy were recorded. Conclusion Patients treated with disopyramide as second-line therapy showed a reduction in symptoms in a quite long-follow-up, avoiding SRT in up to 70% of them. Patients who might benefit the most from the therapy are those who reached LVOTG <50 mmHg during treatment.