Table 1.

Methods to identify left atrial myopathy

Parameter	How to determine LA myopathy	Advantages	Disadvantages
LA maximum volume [13]	-Increased LA volumes at the end of atrial diastole as assessed by biplane method of discs	-Cost-effective -Technology readily available -Associated with poor outcomes in AF-HF	-Potential for foreshortening leading to improper calculation of LA volume -Increased LA volume may not occur until the late stages of LA myopathy
LA minimum volume [14]	-Increased LA volumes at the end of atrial systole as assessed by biplane method of discs	-Cost-effective -Technology readily available -Associated with poor outcomes in AF-HF -Greater association with LA myopathy than LA maximum volume	-Potential for foreshortening leading to improper calculation of LA volume -Increased LA volume may not occur until the late stages of LA myopathy
LA emptying fraction [15, 16]	-Decreased LA emptying fraction, as calculated by the equation: ((LA maximum volume − LA minimum volume)/(LA maximum volume))	-Cost-effective -Technology readily available -Associated with poor outcomes in AF-HF	-Potential for foreshortening leading to improper calculation of LA volumes -Decreased LA emptying fraction may not occur until the late stages of LA myopathy
LA Functional Index [17]	-Decreased LA functional index as calculated by the equation: ((LA emptying fraction × outflow tract velocity time integral)/(LA max volume indexed to BMI))	-Cost-effective -Technology readily available -Can be calculated independent of rhythm -Provides a functional estimate of LA mechanics	-Potential for foreshortening leading to improper calculation of LA volumes -Calculations may be impacted by patient age, heart rate, and LA size
Mitral inflow Doppler pattern [18]	-Decreased A-wave velocity	-Cost effective -Technology readily available	-Cannot be measured in setting of AF -Low velocities may only be present in later stages of disease
LA tissue Doppler [19]	-Decreased a′ tissue velocity (< 5 cm/s)	-Cost effective -Technology readily available	-Potential for inaccuracy due to foreshortened views of the LA -Cannot be measured in the setting of AF -Low velocities may only be present in later stages of disease
LA strain [20]	-Decreased reservoir, conduit or booster strain	-Cost-effective -Technology readily available -Potential to post-process images if strain is not obtained on acquired images -Sensitive measurement of atrial dynamics that can detect changes to LA myocardium early in the disease course -Holds significant prognostic value in AF-HF	-Potential for inaccuracy due to foreshortened views of the LA -Manufacturer-dependent algorithms may lead to discrepant measurements -Potential for user-related error when tracing the endocardial border
Cardiac MRI [21]	-Presence of macroscopic LA scar (late gadolinium enhancement)	-Sensitive and noninvasive method of evaluating LA fibrosis -Ability to provide additional information about myocardial structure	-High cost -Limited availability -Long duration of exam -Dependent on patient participation -Requires specific imaging protocol that may be center-dependent
Four-dimensional flow MRI [22]	-Decreased velocity of flow as determined by post-processing calculations	-Ability to quantify flow through the LA -Sensitive to subtle decreases in flow velocity which infer LA myopathy	-High cost -Limited availability of 4D flow MRI technology -Long duration of exam -Dependent on heart rate and patient participation -Does not provide information about LA myocardial tissue
Electroanatomic mapping [23]	-Areas of decreased voltage in the LA prior to ablation	-High sensitivity in determining areas of impaired LA conduction	-Very high cost -Invasive procedure -Does not provide information about LA mechanical function

Abbreviations: LA left atrium, AF-HF comorbid atrial fibrillation and heart failure, BMI body mass index, AF atrial fibrillation, MRI magnetic resonance imaging