Daily Cardiology Research Analysis
Analyzed 200 papers and selected 3 impactful papers.
Summary
A multicenter double-blind RCT in JAMA found no benefit of sodium bicarbonate during in-hospital cardiac arrest and more metabolic adverse effects, challenging routine use. A JCI preclinical study overturns prior assumptions about TBX18-based biological pacemakers, showing fibrosis and lack of pacemaking, while HCN2 succeeds. A large CMR cohort in JACC Cardiovascular Imaging shows that concomitant mitral regurgitation identifies a high-risk subgroup among patients with moderate aortic stenosis, especially in low-flow states.
Research Themes
- Resuscitation pharmacotherapy and cardiac arrest outcomes
- Cardiac gene therapy and biological pacemaker feasibility
- Valvular heart disease risk stratification using CMR
Selected Articles
1. Sodium Bicarbonate for In-Hospital Cardiac Arrest: A Randomized Clinical Trial.
In a multicenter double-blind RCT (n=913 randomized; primary analysis n=779), sodium bicarbonate during in-hospital cardiac arrest did not improve sustained ROSC, 30-day survival, or favorable neurologic outcome compared with placebo. Alkalosis and hypernatremia were more frequent with bicarbonate.
Impact: This high-quality randomized trial addresses a long-debated practice and provides definitive evidence against routine bicarbonate during in-hospital cardiac arrest.
Clinical Implications: Avoid routine sodium bicarbonate during in-hospital cardiac arrest; reserve for specific indications (e.g., severe hyperkalemia, tricyclic overdose, profound metabolic acidosis) while being mindful of alkalosis/hypernatremia risk.
Key Findings
- Sustained ROSC: 39% with bicarbonate vs 37% with placebo (RR 1.05; P=.62)
- 30-day survival and favorable neurologic outcome numerically higher but not significant in bicarbonate group
- Higher rates of alkalosis and hypernatremia after arrest in the bicarbonate group
Methodological Strengths
- Multicenter, double-blind, placebo-controlled randomized design
- Pre-registered with clearly defined primary and secondary outcomes
Limitations
- Trial conducted within a single national health system; external generalizability may vary
- Not powered for subgroup effects (e.g., severe acidosis or hyperkalemia) and secondary outcomes show wide CIs
Future Directions: Assess targeted use in predefined subgroups (severe metabolic acidosis, hyperkalemia), evaluate out-of-hospital settings, and explore interactions with vasopressor dosing and ventilation strategies.
IMPORTANCE: Patients with in-hospital cardiac arrest have poor outcomes. Sodium bicarbonate is commonly administered during cardiac arrest, but the effects on clinical outcomes are unknown. OBJECTIVE: To determine whether administration of sodium bicarbonate during in-hospital cardiac arrest increases the proportion of patients with return of spontaneous circulation. DESIGN, SETTING, AND PARTICIPANTS: Randomized, parallel-group, double-blind, placebo-controlled clinical trial conducted at 21 hospitals in Denmark. Participants were adults with in-hospital cardiac arrest, who received at least 1 dose of epinephrine. Patients were enrolled from February 6, 2023, to February 11, 2026, with the last 90-day follow-up conducted on May 4, 2026. Final statistical analysis was conducted on May 5, 2026. INTERVENTION: Sodium bicarbonate (up to 100 mmol) or placebo intravenously. MAIN OUTCOMES AND MEASURES: The primary outcome was sustained return of spontaneous circulation. Key secondary outcomes were survival at 30 days and survival at 30 days with a favorable neurologic outcome, defined by a score of 0 to 3 on the modified Rankin Scale (scores range from 0 to 6, with higher scores indicating greater disability). RESULTS: A total of 2913 patients with in-hospital cardiac arrest were screened; 913 patients were randomized, of which 779 were eligible for the primary analyses, with 372 randomized to receive sodium bicarbonate and 407 randomized to receive placebo. The median (IQR) age of patients was 73 (64-79) years and 502 were male (64%). Sustained return of spontaneous circulation occurred in 146 patients (39%) in the sodium bicarbonate group and 150 (37%) in the placebo group (risk ratio, 1.05 [95% CI, 0.88-1.24]; P = .62). At 30 days, 45 patients (12%) in the sodium bicarbonate group and 37 (9.1%) in the placebo group were alive (risk ratio, 1.25 [95% CI, 0.84-1.88]); a favorable neurologic outcome at 30 days occurred in 30 patients (8.1%) and 22 patients (5.4%), respectively (risk ratio, 1.39 [95% CI, 0.82-2.34]). Alkalosis and hypernatremia after cardiac arrest were more common in the sodium bicarbonate group. CONCLUSIONS AND RELEVANCE: There was no significant difference in sustained return of spontaneous circulation between sodium bicarbonate and placebo in adults with in-hospital cardiac arrest. These findings do not support routine administration of sodium bicarbonate for patients with in-hospital cardiac arrest. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05564130; ClinicalTrialsRegister.eu Identifier: 2022-501304-10-00.
2. AAV-mediated long-term TBX18 expression causes cardiac fibrosis and fails to induce pacemaker activity in rodents.
Long-term AAV-mediated TBX18 expression caused severe cardiac fibrosis in mice and, at non-fibrogenic levels, failed to induce pacemaker gene programs or funny current. In contrast, AAV-Hcn2 enabled robust ectopic pacing in an AV-block rat model.
Impact: This work overturns prior optimism about TBX18-based biological pacemakers and redirects the field toward alternative targets such as HCN2, with crucial safety implications.
Clinical Implications: TBX18 should not be advanced clinically for biological pacemakers without addressing fibrosis and lack of pacemaker phenotype; HCN2 appears more promising but requires rigorous translational safety and efficacy testing.
Key Findings
- CMV-driven long-term TBX18 expression induced severe cardiac fibrosis in mice.
- At non-fibrogenic expression, TBX18 suppressed working myocardial genes but failed to induce pacemaker programs and did not generate funny current.
- In AV-block rats, AAV-Hcn2 produced robust ectopic pacing (with isoproterenol), whereas TBX18 did not and did not augment Hcn2 pacing.
Methodological Strengths
- Rigorous in vivo comparison of transcription factor (TBX18) versus ion channel (HCN2) strategies across rodent models
- Integrated electrophysiological, transcriptional, and phenotypic assessments to link mechanism to function
Limitations
- Findings are limited to rodent models; translatability to large animals/humans is uncertain
- Promoter choice (CMV) and vector/dose may influence fibrosis and expression patterns
Future Directions: Evaluate tissue-specific promoters and controlled expression systems in large-animal models, explore combination or alternative ion channel strategies, and perform chronic safety studies.
Gene therapy-based biological pacemakers have been proposed as an alternative to their hardware-based counterparts. In this context, short-term ectopic expression of the T-box transcription factor 18 (TBX18) in the ventricle has been reported to generate potent short-term pacemaker function in various animal models. Here, we investigated the impact of adeno-associated virus (AAV)-mediated long-term expression of TBX18, and compared the outcomes to those of the pacemaker ion channel Hcn2. Our findings revealed that CMV-driven ectopic TBX18 expression in mouse hearts led to severe cardiac fibrosis. At lower, non-fibrogenic levels, TBX18 maintained its transcriptional function but failed to induce pacemaker phenotypes. TBX18-expressing cells showed suppressed expression of key working myocardial genes, but the pacemaker gene program was not induced. Electrophysiological studies showed abnormal automaticity in TBX18-expressing cells, combined with prolonged repolarization and various current changes. However, no hyperpolarization-activated funny current was detected. In a complete AV-block rat model, AAV-mediated Hcn2 expression induced robust ectopic pacemaker activity in the presence of isoproterenol, whereas TBX18 expression neither generated such activity nor augmented Hcn2-mediated pacing. In conclusion, at functionally non-fibrogenic levels, TBX18 is neither sufficient nor necessary to induce pacemaker activity. In contrast, Hcn2 generates reliable pacing, making it a more viable candidate for biological pacemaker development.
3. Impact of Concomitant Mitral Regurgitation in Moderate Aortic Stenosis: Assessment of Remodeling and Clinical Outcomes.
In a CMR-based cohort of 742 AS patients, those with moderate AS plus moderate-or-greater MR had greater symptoms, adverse remodeling, and higher risk of cardiovascular death or heart failure hospitalization (adjusted HR 1.86). Risk was accentuated in low-flow physiology (SVI ≤35 mL/m²).
Impact: Identifies a clinically important high-risk subgroup (moderate AS with MR), informing surveillance and potential earlier intervention strategies, particularly in low-flow states.
Clinical Implications: In moderate AS, incorporate MR burden and flow status (SVI) into risk stratification; consider closer follow-up, optimization of medical therapy, and earlier multidisciplinary evaluation for intervention in symptomatic low-flow patients.
Key Findings
- Among moderate AS (n=422), 76 had moderate-or-greater MR with higher NYHA II–IV prevalence (80.3%).
- Concomitant MR associated with larger LV volumes, lower LVEF, and reduced aortic forward flow on CMR.
- Coexisting MR independently predicted cardiovascular death or HF hospitalization (adjusted HR 1.86; 95% CI 1.31–2.65; P<0.001), especially in low-flow (SVI ≤35 mL/m²).
Methodological Strengths
- Large CMR-based cohort with detailed remodeling and flow quantification
- Multivariable Cox modeling across AS severity strata and MR burden
Limitations
- Observational design with potential residual confounding; treatment decisions not randomized
- Median follow-up of 1.8 years may undercapture late events; abstract truncation limits some numeric details
Future Directions: Prospective trials to test earlier intervention strategies in moderate AS with MR, especially low-flow; standardized CMR thresholds to guide timing of therapy.
BACKGROUND: Patients with moderate aortic stenosis (AS) and concomitant mitral regurgitation (MR) often present with symptoms despite neither lesion individually reaching intervention thresholds. The clinical impact of this dual valvular disease remains a knowledge gap. OBJECTIVES: The aims of this study were to evaluate the effect of concomitant MR on cardiac remodeling and clinical outcomes in patients with moderate AS using cardiac magnetic resonance (CMR) and to compare with isolated moderate and severe AS. METHODS: A total of 742 patients with at least moderate AS on CMR (422 with moderate AS, 320 with severe AS) were studied. Patients were stratified by AS severity and MR burden. Remodeling parameters, symptoms, and outcomes, including cardiovascular death and heart failure hospitalization, were analyzed. Multivariable Cox models identified covariates associated with outcomes. RESULTS: Among 422 patients with moderate AS, 76 had moderate or greater MR. Compared with isolated moderate AS, combined AS and MR was associated with higher symptom burden (80.3% in NYHA functional classes II-IV), more pronounced remodeling (larger indexed left ventricular volumes, lower left ventricular ejection fractions), and reduced aortic forward flow. Over a median 1.8 years, coexisting moderate or greater MR was independently associated with cardiovascular death or heart failure hospitalization (adjusted HR: 1.86; 95% CI: 1.31-2.65; P < 0.001). This risk was more apparent in the low-flow subgroup (stroke volume index ≤35 mL/m CONCLUSIONS: Patients with moderate AS and MR constitute a high-risk subgroup with high symptom burden, adverse cardiac remodeling, and poor clinical outcomes. Risk appears more pronounced in the setting of reduced forward flow (stroke volume index ≤35 mL/m