Katsuji Inoue

Scintigraphy using ^99m Tc-PYP as a bone-avid radiotracer reveals physiological and pathologic accumulation of the tracer in the extraosseous tissues and organs—including the breasts—in addition to the bones. ^99m Tc-PYP scintigraphy also reveals deposits of wild-type amyloid transthyretin (ATTRwt) in the myocardium and extracardiac sites, such as subcutaneous fat, skeletal trunk muscles, and alimentary tract, of patients with ATTRwt cardiomyopathy (CM). We describe an 87-year-old man with ATTRwt-CM in whom myocardial ^99m Tc-PYP uptake was reduced and mammary tracer uptake was increased due to gynecomastia after treatment with a disease-modifying drug for ATTRwt-CM, tafamidis, and heart failure medications, including spironolactone.

Aims: Current recommendations for echocardiography-based classification of left ventricular filling pressure (LVFP) as normal or elevated, are based on an algorithm and parameter selection determined by human experts. We tested whether machine learning (ML) can improve classification of LVFP and investigated which parameters were deemed most important by different ML models. Methods and results: In a multicentre study, echocardiography was performed simultaneously with, or within 24 h of, heart catheterization in 250 patients. Eight different ML models were trained and tested using a nested cross-validation procedure to classify LVFP as normal or elevated. The training included a search and selection of the most useful parameters. Performance was assessed from the test sets not seen during training. The eight ML models could classify all patients regardless of missing parameter values with accuracy ranging from 82% to 86%. The 2016 ASE/EACVI guidelines algorithm left 13% unclassified due to missing values and had an accuracy of 81% in the remaining patients. On average, the eight ML models selected 13 parameters, and left atrial strain was included in three of these. The five highest ranked parameters by the ML models were mitral E/left atrial reservoir strain, log(NT-proBNP), tricuspid regurgitation velocity, septal E/e’, and E/A. Conclusion: ML can improve classification of LVFP, particularly with a higher feasibility. The study unveiled less used parameters as some of the most valuable for evaluating LVFP.

BACKGROUND: Evaluation of whether dyspnea has a cardiac cause is essential. Guidelines from 2016 were reported to result in a high incidence of indeterminate left ventricular (LV) filling pressure. We sought to validate a new algorithm for the estimation of LV filling pressure (LVFP) in a multicenter study, with the objective of decreasing the yield of indeterminate filling pressure and increasing accuracy. METHODS: In an observational study, echocardiography was performed in 951 patients referred for cardiac catheterization. Echocardiographic measurements included mitral inflow, pulmonary vein and tissue Doppler mitral annulus velocities, tricuspid regurgitation velocity, assessment of mean right atrial pressure, biplane LV and left atrial volumes, and LV and left atrial strain. A stepwise approach was applied in a new algorithm for estimation of LVFP, whereby pressure >15 mm Hg was considered abnormally elevated. The first step included mitral annulus early diastolic velocity (e′), the ratio of mitral early flow velocity to e′, and pulmonary artery systolic pressure. With concordant findings in all 3 variables, conclusions about LVFP could be reached. In case of discordant or incomplete variables, left atrial reservoir strain, left atrial maximum volume index, isovolumic relaxation time, and pulmonary vein flow were analyzed in a second step. In the presence of ≥1 abnormal measurement in the second step, the conclusion of elevated LVFP could be reached. RESULTS: Only 2 patients had indeterminate LVFP as per the new algorithm versus 38 applying 2016 guidelines ( P P P P P <0.0001). CONCLUSIONS: The new algorithm increases the feasibility of estimating LVFP and has good accuracy with incremental value when natriuretic peptides are considered.

The importance of left atrial (LA) function is recognized, especially when left ventricular function fails or atrial fibrillation occurs and heart failure (HF) develops. A compensatory mechanism of LA function unremittingly operates to maintain cardiac performance and prevent the occurrence of HF. LA function consists of three components: booster pump, reservoir, and conduit function. Echocardiography enables assessment of these components of LA function by LA volumetric changes in one cardiac cycle. Currently, LA strain has emerged as a valuable diagnostic and prognostic tool in patients with various cardiovascular diseases. An aging society is confronted with an issue of public health due to an increased number of patients with heart failure with preserved ejection fraction (HFpEF). Because effective medical and interventional approaches for patients with HFpEF are limited, early diagnosis and prevention are important to avoid a transition from preclinical HF stage to clinically overt HFpEF. Echocardiography with LA strain analysis and exercise stress echocardiography have the potential to identify patients with undiagnosed HFpEF, thus facilitating several preventive and therapeutic interventions. In this review, the development, measurement, and clinical application of LA strain are summarized and future perspectives in preventive medicine, accurate diagnosis, and therapeutic guidance for patients with HF are discussed. Graphical abstract Clinical application of LA strain. A. Mitral inflow patterns and LA strain curves in LVDD. A cutoff value of LA reservoir strain of 35% can differentiate patients with LVDD grade 0 from those with LVDD grades 1–3. Similarly, an LA strain of 24% distinguishes patients with LVDD grades 0–1 from those with LVDD grades 2–3, while an LA strain of 19% serves as a threshold to differentiate LVDD grades 0–2 from grade 3. The percentage values on the LA strain curves represent the LA reservoir strain values corresponding to the white-dotted line. B. LA reservoir strain can be used to estimate LV filling pressure. A cutoff value < 18% for reservoir strain can be used to estimate an elevated LV filling pressure > 12 mmHg. C. LA reservoir strain at rest can be used to diagnose HFpEF. This case was a 75-year-old woman with a history of repeated catheter ablation for AF evaluated for progressive symptoms of exertional dyspnea despite maintaining a sinus rhythm. She had a normal LV ejection fraction of 65% with an enlarged left atrium (LA volume index 57 mL/m²) and reduced LA reservoir strain of 13% (left panel). Right heart catheterization showed mildly elevated pulmonary capillary wedge pressure at rest (a-wave, 18 mmHg; v-wave, 24 mm Hg). However, the pulmonary capillary wedge pressure increased during exercise (a-wave, 34 mmHg) with large v-waves (47 mmHg), suggesting severely reduced LA compliance (right panel). D. LA reservoir strain at rest can be used to predict future HF events in patients with preserved LV ejection fraction. Patients with a low LA reservoir strain value ≤ 21% experienced more HF events than those with a high LA strain value > 21%. LA, left atrial; HF, heart failure; LV, left ventricular; DD, diastolic dysfunction; HFpEF, heart failure with preserved ejection fraction.