Table 2.

Investigations performed in the workup of patients proposed for ASA

Category	Test	Rationale
Haematological	U&Es	Secondary organ dysfunction
		Often abnormal in phenocopies (HTN, Anderson-Fabry, infiltration)
	CK	Rule out syndromes such as myotonic dystrophy
	FBC	Rule out anaemia as a cause of dyspnoea
	α-galactosidase	Consider in cases where there is clinical suspicion of Anderson-Fabry disease
ECG	12-lead ECG	Help distinguish phenocopies:
		Small QRS – infiltrative myocardial disease
		Excessively large QRS – Pompe's, Danon's syndromes
		1st degree HB – storage disease
		AV block – infiltration, Anderson-Fabry
		Pre-excitation – Pompe's, Danon's syndromes
		Extreme axis deviation – Noonan's syndromes
	24-h ECG	Consideration of SCD risk and potential for ICD implantation before ASA
	24-h BP monitor	Consider in cases where a phenocopy of hypertensive heart disease is suspected
Imaging	Echocardiogram	Assess:
		Septal size
		Extent of SAM
		LVOT gradient extent and localisation, rest and with Valsalva manoeuvre
		Diastolic function
	Cardiac MRI	Assess:
		Septal size and distribution of hypertrophy
		Presence of HCM variant such as abnormal direct papillary muscle insertion into MV leaflets, antero-apical displacement of anterior papillary muscle, sub-aortic band
		Assess pre-existing scar; risk of SCD and comparison of iatrogenic scar location post-ASA
	CT coronary angiography	Plan access to septal arteries that supply target myocardium
		Rule out significant coronary artery disease that will require CABG
Functional	PFTs	Rule out significant lung disease as the primary driver to dyspnoea
	CPEX	Assess:
		Functional capacity (baseline to compare with post-ASA)
		Primary cause of dyspnoea
		Prognostic implications