AIMS Treatment options for patients with non-obstructive hypertrophic cardiomyopathy (HCM) are limited. We sought to determine whether biventricular (BiV) pacing improves exercise capacity in HCM patients, and whether this is via augmented diastolic filling. METHODS AND RESULTS Thirty-one patients with symptomatic non-obstructive HCM were enrolled. Following device implantation, patients underwent detailed assessment of exercise diastolic filling using radionuclide ventriculography in BiV and sham pacing modes. Patients then entered an 8-month crossover study of BiV and sham pacing in random order, to assess the effect on exercise capacity [peak oxygen consumption (VO2 )]. Patients were grouped on pre-specified analysis according to whether left ventricular end-diastolic volume increased (+LVEDV) or was unchanged/decreased (-LVEDV) with exercise at baseline. Twenty-nine patients (20 male, mean age 55 years) completed the study. There were 14 +LVEDV patients and 15 -LVEDV patients. Baseline peak VO2 was lower in -LVEDV patients vs. +LVEDV patients (16.2 ± 0.9 vs. 19.9 ± 1.1 mL/kg/min, P = 0.04). BiV pacing significantly increased exercise ΔLVEDV (P = 0.004) and Δstroke volume (P = 0.008) in -LVEDV patients, but not in +LVEDV patients. Left ventricular ejection fraction and end-systolic elastance did not increase with BiV pacing in either group. This translated into significantly greater improvements in exercise capacity (peak VO2  + 1.4 mL/kg/min, P = 0.03) and quality of life scores (P = 0.02) in -LVEDV patients during the crossover study. There was no effect on left ventricular mechanical dyssynchrony in either group. CONCLUSION Symptomatic patients with non-obstructive HCM may benefit from BiV pacing via augmentation of diastolic filling on exercise rather than contractile improvement. This may be due to relief of diastolic ventricular interaction. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov NCT00504647.

中文翻译：

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双心室起搏器治疗通过增强运动时的舒张充盈来提高非梗阻性肥厚型心肌病患者的运动能力。

非阻塞性肥厚型心肌病 (HCM) 患者的 AIMS 治疗选择有限。我们试图确定双心室 (BiV) 起搏是否能提高 HCM 患者的运动能力，以及这是否是通过增强舒张期充盈。方法和结果 31 名有症状的非阻塞性 HCM 患者被纳入研究。植入装置后，患者在 BiV 和假起搏模式下使用放射性核素心室造影对运动舒张期充盈进行了详细评估。然后，患者以随机顺序进入 BiV 和假起搏的 8 个月交叉研究，以评估对运动能力的影响 [峰值耗氧量 (VO2)]。根据基线运动时左心室舒张末期容积是增加（+LVEDV）还是不变/减少（-LVEDV），对患者进行预先指定的分析。29 名患者（20 名男性，平均年龄 55 岁）完成了研究。有 14 名 +LVEDV 患者和 15 名 -LVEDV 患者。-LVEDV 患者的基线峰值 VO2 低于 +LVEDV 患者（16.2 ± 0.9 vs. 19.9 ± 1.1 mL/kg/min，P = 0.04）。BiV 起搏显着增加 -LVEDV 患者的运动 ΔLVEDV (P = 0.004) 和 Δ 每搏输出量 (P = 0.008)，但在 +LVEDV 患者中没有。在任一组中，左心室射血分数和收缩末期弹性没有随着 BiV 起搏而增加。这转化为运动能力（峰值 VO2 + 1.4 mL/kg/min，P = 0.03）和生活质量得分（P = 0. 02) 在交叉研究期间在-LVEDV 患者中。两组对左心室机械不同步均无影响。结论 有症状的非阻塞性 HCM 患者可能受益于 BiV 起搏，通过增加运动时的舒张充盈而不是改善收缩。这可能是由于舒张期心室相互作用的缓解。临床试验注册 ClinicalTrials.gov NCT00504647。