Myocarditis is a heterogeneous disease with diverse etiologies and clinical trajectories. Traditionally, its diagnosis has been guided by the Dallas criteria, which focus on histopathological features. Clinically, myocarditis is categorized as acute or chronic based on the duration since symptom onset. However, recent expert consensus, particularly in Western countries, has redefined myocarditis as either acute myocarditis or chronic inflammatory cardiomyopathy, including inflammatory dilated cardiomyopathy, reflecting advancements in viral genome analysis and histopathology. In 2023, the Japanese Circulation Society proposed the concept of chronic active myocarditis, a high-risk phenotype characterized by persistent inflammation and ongoing cardiomyocyte injury. The transition from acute myocarditis to its chronic phase involves complex immune mechanisms, with sustained myocardial inflammation driving ventricular remodeling and progression to heart failure. Cardiac magnetic resonance imaging and endomyocardial biopsy remain pivotal diagnostic modalities, though their diagnostic yield varies according to disease phase. Management strategies focus on heart failure treatment, arrhythmia control, and, in select cases, immunosuppressive therapy, particularly for virus-negative inflammatory cardiomyopathy. Although antiviral therapy has shown promise, its clinical efficacy remains uncertain. Given the evolving understanding of the chronic phase of myocarditis, further research is warranted to refine the diagnostic criteria and optimize personalized therapeutic strategies. This review gives a comprehensive overview of the pathophysiology, classification, and management of chronic myocarditis, with an emphasis on emerging disease concepts and their clinical implications.

Background: Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM). Validation of the Japanese Circulation Society (JCS)/Japanese Heart Failure Society (JHFS) guidelines for SCD prevention needs to be undertaken in a large cohort of Japanese patients with HCM.

Methods and Results: In a subanalysis of the REVEAL-HCM registry comprising 3,611 patients, we enrolled 3,547 patients after excluding 64 patients with missing data required for calculating the HCM Risk-SCD score. The endpoint was a composite of SCD or an equivalent event. During a median 5.8-year follow-up period, SCD events occurred in 247 (7.0%) patients. The 5-year cumulative incidence of SCD events differed significantly between Class 2a and 2b recommendations (6.7% vs. 4.9%, respectively; P=0.006) and between Class 2b and 3 recommendations (4.9% vs. 1.7%, respectively; P<0.001). Excess risk of SCD was also significant for patients with Class 2a and 2b compared with Class 3 recommendations, with hazard ratios of 3.59 (95% confidence interval [CI] 2.40–5.37; P<0.001) and 2.09 (95% CI 1.47–2.97; P<0.001), respectively. The 2018 JCS/JHFS guidelines had an area under the curve of 0.75 (95% CI 0.71–0.80; P<0.001) for discriminating SCD events at 5 years.

Conclusions: The 2018 JCS/JHFS guidelines showed good discriminatory performance for SCD risk stratification, particularly among patients with Class 2a recommendations for an implantable cardioverter defibrillator.

Background: HeartMate 3 (HM3), a magnetically levitated centrifugal-flow pump, has demonstrated superior hemocompatibility and reduced adverse events compared to HeartMate II (HMII), an axial-flow pump, in global studies. However, because long-term comparative data in Japanese patients remain scarce, in the present study we evaluated the 5-year outcomes of HM3 support by comparing them with those of HMII at 2 leading left ventricular assist device (LVAD) centers in Japan.

Methods and Results: We retrospectively analyzed 364 patients who underwent primary LVAD implantation (HM3: n=168; HMII: n=196) between 2010 and 2023. The primary endpoint included survival to transplant, recovery, or continued LVAD support free from stroke or pump replacement. At 5 years, freedom from the composite endpoint was higher in the HM3 group (75% vs. 52%; hazard ratio [HR] 0.52; P=0.001), although overall survival was comparable (90% vs. 85%; P=0.44). The HM3 group experienced significantly fewer strokes (HR 0.40; P=0.0008), bleeding events (HR 0.22; P<0.0001), and pump thrombosis (HR 0.09; P=0.003). Rates of rehospitalization, driveline infections, and late right heart failure did not differ between the groups.

Conclusions: HM3 support significantly improved long-term event-free outcomes compared to HMII, despite comparable overall survival, supporting the use of HM3 as durable mechanical circulatory support devices in Japan.

Background: Hospitalization for heart failure (HF) is associated with poor outcomes, yet the temporal patterns of laboratory biomarkers surrounding such events remain inadequately described. This study aimed to characterize trajectories of routinely measured biomarkers before and after HF hospitalization.

Methods and Results: We retrospectively analyzed patients hospitalized for acute HF at Nagoya University Hospital between January 2018 and December 2023. In the main cohort, outpatient levels of B-type natriuretic peptide (BNP), creatinine, hemoglobin, hematocrit, uric acid, sodium, and potassium were evaluated for 1 year following discharge. A second cohort included patients with ≥2 hospitalizations, assessing biomarker trends 1 year before and after the second admission. The main cohort included 709 patients (7,299 laboratory visits). Of them, 191 patients with rehospitalization comprised the second cohort (3,318 visits). In the main cohort, BNP, creatinine, uric acid, hemoglobin, and hematocrit declined for 60 days post-discharge, followed by increases. In the second cohort, BNP, creatinine, and uric acid levels began to rise 60 days before rehospitalization (e.g., BNP increased by 185.2 pg/mL per 30 days, 95% confidence interval: 138.1 to 232.3, P<0.001), while hemoglobin, hematocrit, and sodium declined.

Conclusions: Biomarkers exhibited distinct patterns before and after HF hospitalization. A BNP increase of approximately 200 pg/mL per 30 days within 60 days prior to admission may represent a practical, non-invasive marker to guide early intervention.

Background: Heart failure with mildly reduced ejection fraction (HFmrEF) is a distinct but relatively understudied phenotype of heart failure. Traditional measures, such as ejection fraction and global longitudinal strain (GLS), have limited prognostic value in HFmrEF, prompting interest in global myocardial work (GMW) as a more comprehensive marker. This study investigated the prognostic utility of GMW in HFmrEF.

Methods and Results: In this retrospective study, 273 patients with HFmrEF diagnosed between 2014 and 2018 were followed for a median of 31 months. Forty-eight patients experienced hospitalization for heart failure (HHF). The global work index (GWI), GLS, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEi/ARB) use were significantly associated with HHF risk. Univariate Cox regression showed that GWI (hazard ratio [HR] 0.998; 95% confidence interval [CI] 0.997–0.999; P=0.003), global constructive work (HR 0.999; 95% CI 0.998–1.000; P=0.010), ACEi/ARB use (HR 0.464; 95% CI 0.239–0.902; P=0.024), and GLS (HR 1.058; 95% CI 1.004–1.116; P=0.035) were significant predictors of HHF. In multivariable analysis, higher GWI was independently associated with a lower risk of HHF (HR 0.997; 95% CI 0.996–0.998; P=0.001). Notably, GWI ≥850 mmHg% was associated with a significantly lower HHF risk (HR 0.075; 95% CI 0.0288–0.196; P=0.001).

Conclusions: GWI is an independent prognostic marker for HHF in HFmrEF, offering incremental value beyond conventional echocardiographic parameters. However, validation in prospective and multicenter studies is warranted.

Background: Left ventricular (LV) dyssynchrony worsens with heart failure (HF) progression. However, the early identification of LV dyssynchrony is challenging, and its prognostic value remains unclear. We aimed to evaluate the prognostic value of LV dyssynchrony based on bandwidth (time width within which 95% of the LV myocardium begins to contract), assessed using Heart Risk View (HRV) analysis of myocardial perfusion scintigraphy data.

Methods and Results: This was a post hoc analysis of a prospective, non-randomized, single-center cohort study conducted between January 2019 and December 2023. This study included 584 patients (mean age 72.2±13.0 years; 425 [72.8%] males; non-ischemic 29.8%; LV ejection fraction [LVEF] 46.4±15.0%) who were admitted for HF and had LV dyssynchrony evaluated using HRV-based analysis. The composite endpoint was all-cause mortality and HF rehospitalization. Univariate and multivariate logistic regression showed LV dyssynchrony as a significant predictor of HF prognosis (bandwidth threshold 28.0°). Multiple regression analysis identified QRS width, LVEF, and ischemic cardiomyopathy as significant determinants of bandwidth. Prognosis was poorer in high-bandwidth groups defined by the median (21.0°) or threshold bandwidth (28.0°). Combined with B-type natriuretic peptide, bandwidth improved prognostic utility. Bandwidth showed a moderate correlation with QRS width and strong correlations with end-systolic volume and LVEF.

Conclusions: HRV-derived bandwidth is a non-invasive and safe method providing automatic, objective, and reproducible measurements. It is useful for predicting HF prognosis.

Background: Cardiac computed tomography (CCT) not only evaluates coronary artery disease but also characterizes myocardial features through late iodine enhancement (LIE). This study evaluated the clinical characteristics and prognostic significance of incidentally detected non-ischemic LIE patterns in patients undergoing CCT for coronary artery evaluation.

Methods and Results: We retrospectively analyzed 465 patients who underwent CCT between January 2020 and December 2021. The primary outcome was all-cause death, and the secondary outcome was cardiovascular events, defined as cardiac death and unplanned cardiovascular hospitalization. Cox hazard analysis was performed to identify parameters significantly associated with the outcomes. After excluding patients with non-ischemic cardiomyopathy diagnosed before and after undergoing CCT, coronary stenosis and previous revascularization, 57 patients had non-ischemic LIE and 408 showed no LIE. Compared with patients without LIE, non-ischemic LIE was significantly associated with increased high-sensitivity cardiac troponin T and B-type natriuretic peptide levels, left ventricular (LV) diastolic diameter, LV thickness, and impaired LV ejection fraction. The cumulative incidence of cardiovascular events was significantly higher in patients with non-ischemic LIE than in those without LIE (log-rank P=0.024). In the Cox multivariable analysis, non-ischemic LIE was associated with cardiovascular events (hazard ratio 7.01; 95% confidence interval 1.09–42.2; P=0.041).

Conclusions: CCT may provide prognostic significance through the assessment of myocardial properties.

Background: Passive leg lifting (PLL) may serve as a simple alternative to simulate exercise stress.

Methods and Results: We evaluated 33 patients with PH who underwent PLL-RHC and exercise right heart catheterization (RHC); 25 patients were classified as having PLL-induced PH (LIPH), demonstrating significant increases in mean pulmonary arterial pressure (mPAP) and mPAP–cardiac output slopes. Strong correlations were observed between PLL-RHC and exercise RHC measurements.

Conclusions: PLL-RHC may represent a simple method for detecting EIPH.

Background: Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death in patients with heart failure, but the value of ICD therapy after left ventricular ejection fraction (LVEF) recovery is uncertain.

Methods and Results: We retrospectively studied 118 patients undergoing primary prevention ICD therapy (2013–2022). Of them, 40 (34%) improved to LVEF >35% (impEF). Over 4.4 years, appropriate ICD therapy occurred significantly less in the impEF group vs. the persistently low LVEF group (P=0.008), but 4 impEF patients still required antitachycardia pacing therapy. No patient with LVEF ≥40% received such therapy.

Conclusions: LVEF recovery reduces but does not eliminate ventricular arrhythmia risk, supporting individualized ICD management.

Background: Right ventricular endomyocardial biopsy may cause conduction disturbances, particularly complete right bundle branch block (CRBBB); however, the impact of using the venous access site remains unclear.

Methods and Results: In 274 patients, CRBBB occurred more frequently with the transfemoral than with the transjugular approach (29.2% vs. 6.7%, P<0.001). The transjugular approach independently reduced CRBBB risk (odds ratio 0.17, P<0.001). Sustained CRBBB was also less frequent (8.3% vs. 1.1%, P=0.007). Major complications, including stroke, pacemaker implantation, and death, were absent.

Conclusions: The transjugular approach reduces CRBBB risk and is a safer option for patients at risk of complete atrioventricular block.

Background: Patients with infective endocarditis (IE) on maintenance hemodialysis (HD) have poor outcomes, but contemporary data remain limited.

Methods and Results: We conducted a retrospective analysis using a nationwide Japanese administrative database and identified 12,158 patients hospitalized with IE between 2018 and 2021, including 806 (6.6%) on maintenance HD. The inhospital mortality rate was significantly higher in HD patients (30.0% vs. 13.5%, P<0.05).

Conclusions: Maintenance HD patients with IE had worse outcomes, underscoring the need for early recognition and tailored management in this highrisk group.

Background: Little is known about the recently emerging entity, heart failure with supranormal ejection fraction (HFsnEF).

Methods and Results: Subanalysis of a nationwide, prospective, observational registry that included compensated ambulatory patients with chronic HF and left ventricular ejection fraction (LVEF) >40%. Among the 4,387 patients (mean age 77 years, 43% female), 1,423 had HFsnEF. They were older, more often female, had lower natriuretic peptide levels, and exhibited smaller LV. The prescription rate of guideline-directed medical therapy was lower.

Conclusions: HFsnEF is a common and distinct phenotype characterized by a unique profile and treatment.