Cardiopulmonary exercise testing: a complementary tool to assess risk of ventricular arrythmias in hypertrophic cardiomyopathy

Introduction

Hypertrophic cardiomyopathy (HCM) is linked to an elevated risk of ventricular arrhythmias (VA) and sudden cardiac death (SCD). Cardiopulmonary exercise test (CPET) parameters, including peak oxygen consumption (pVO2) and ventilatory efficiency (VE/VCO2 slope), are currently employed to assess functional capacity, prognosis, and arrhythmic risk.

Aim

To evaluate the relationship/association between CPET parameters and VA in HCM patients.

Methods

Single-center retrospective study evaluating the associa&on between CPET parameters and VA in HCM pa&ents (pts) who underwent CPET between 2018-2025. Sustained (SVT) or non-sustained ventricular tachycardia (NSVT) was detected via 24-hour holter monitoring, implantable loop recorder or implantable cardioverter-defibrillator (ICD).

Results

Sixty-seven consecutive HCM pts underwent CPET (66% male, mean age 57±16 years, 19% with obstruc&ve HCM). In a mean follow-up of 69±50 months, SVT occurred in 7%, and NSVT in 42%. Pts with NSTV included more females (50% vs 23%, p=0.024) and had a higher extension of late gadolinium enhancement (LGE) (16% vs 9.6%, p=0.049) compared to pts without VAs during follow-up.

Pts with NSVTs showed a higher VE/VCO2 slope (p=0.006), higher cardiorespiratory op&mal point (COP)(p=0.022), and lower maximal heart rate (HR)(p=0.019) compared to patients without VA.

In a univariate regression analysis, a higher VE/VCO2 slope (adjusted OR 1.125, p=0.009), and higher CROP (adjusted OR 1.14, p=0.029) were significantly associated with occurrence of NSVT. The prognos&c value of VE/VCO2 slope was confirmed in both submaximal (adjusted OR 1.165, p = 0.041) and maximal (adjusted OR 1.115, p=0.019) exercise testing. The prognostic value of COP was also confirmed for both maximal and submaximal efforts.

Maximal HR was significantly associated with NSVTs only in patients with submaximal effort (adjusted OR 0.997, p=0.021).

pVO2 did not show a significant association with VAs (p=0.222) nor percent of predicted pVO2 (p=0.117).

In a multivariate regression analysis VE/VCO2 slope remained an independent predictor of NSVT even after adjusting for sex, age, genotype, wall thickness, (adjusted OR 1.173, p=0.037), but not for %LGE (p=0.546). This multivariate predictive value was only present during maximal CPET tests, not submaximal (p=0.918).

ROC curve analysis showed moderate discriminatory ability for VE/VCO2 slope (AUC=0.696, p=0.002, cutoff 28.9). COP was also significant but with lower accuracy (AUC=0.678, p=0.012, cutoff 24.35). ROC curve for pVO2 demonstrated poor discriminatory ability (AUC=0.321).

Conclusion

VE/VCO2 slope was an independent prognostic marker for the prediction of NSVT in pa&ents with HCM, showing a higher predictive value than pVO2 or COP, highlighting the role of CPET as an additional stratification tool for ventricular arrhythmic risk assessment in HCM patients.For image description, please refer to the figure legend and surrounding text.