Daily Cardiology Research Analysis
Three studies stand out today: extreme humidity—rather than heat—was linked to increased ventricular arrhythmia risk in patients with cardiac devices; a validated CHARM score offers objective mortality prediction for heart-transplant waitlist candidates; and an RCT in Haiti shows that treating prehypertension in people with HIV safely lowers blood pressure and markedly reduces incident hypertension.
Summary
Three studies stand out today: extreme humidity—rather than heat—was linked to increased ventricular arrhythmia risk in patients with cardiac devices; a validated CHARM score offers objective mortality prediction for heart-transplant waitlist candidates; and an RCT in Haiti shows that treating prehypertension in people with HIV safely lowers blood pressure and markedly reduces incident hypertension.
Research Themes
- Climate and cardiovascular electrophysiology
- Risk stratification and organ allocation in advanced heart failure
- Early antihypertensive therapy in people with HIV
Selected Articles
1. Effects of Extreme Humidity and Heat on Ventricular Arrhythmia Risk in Patients With Cardiac Devices.
In a case time-series of 5,944 device patients linked to geocoded weather data, extreme humidity (95th percentile, 90% RH) increased VT/VF odds over the subsequent 7 days (aOR 1.23; 95% CI 1.00–1.51), with strongest effects in individuals with CAD, HF, diabetes, hypertension, and in socioeconomically deprived areas. High temperatures alone were not associated with VT/VF.
Impact: This is among the first large-scale analyses linking extreme humidity to ventricular arrhythmias, integrating clinical, environmental, and community-level exposures with advanced time-series modeling.
Clinical Implications: Implement humidity-aware risk alerts and remote monitoring for high-risk device patients during humid spells; tailor counseling for patients with CAD/HF/diabetes; public health and urban planning (greenspace) may mitigate vulnerability.
Key Findings
- Extreme humidity (95th percentile, 90% RH) increased VT/VF odds over 7 days (aOR 1.23; 95% CI 1.00–1.51).
- Greatest humidity-related risk among males, age 67–75, and those with CAD, HF, diabetes, hypertension, or prior MI.
- Communities with high socioeconomic deprivation and income inequality, and urban areas with less greenspace, had higher risk.
- High temperatures were not associated with VT/VF events.
Methodological Strengths
- Case time-series design with distributed lag nonlinear models captures short-term exposure–response.
- Geocoded linkage of daily weather to individual residential addresses; adjustment for temporal and individual factors.
Limitations
- Observational design; residual confounding (e.g., indoor climate, medications) possible.
- Generalizability limited to North Carolina device population; exposure misclassification cannot be fully excluded.
Future Directions: Prospective multicenter studies integrating personal humidity exposure, physiologic monitoring, and intervention trials (e.g., cooling/dehumidification, adaptive pacing or alerting) to reduce arrhythmic events.
BACKGROUND: Climate change is increasing the frequency of high heat and high humidity days. Whether these conditions can trigger ventricular arrhythmias [ventricular tachycardia/ventricular fibrillation, VT/VF] in susceptible persons is unknown. OBJECTIVES: The purpose of this study was to determine the relationship between warm-season weather conditions and risk of VT/VF in individuals with pacemakers and defibrillators. METHODS: Baseline clinical and device data from 5,944 patients in North Carolina (2010-2021) were linked to daily weather data geocoded to individuals' residential addresses. Associations between extreme humidity, temperature, and VT/VF overall and by patient, community, and built environment factors were estimated using a case time-series design with distributed lag nonlinear models, adjusting for temporal trends and individual factors.
2. The Colorado Heart Failure Acuity Risk Model: A Mortality Model for Waitlisted Cardiac Transplant Patients.
Using 4,176 U.S. heart-transplant waitlist cases, CHARM incorporated biomarkers (BNP, creatinine, sodium, AST, albumin, bilirubin) and advanced support variables (ECMO, mechanical support, ventilation) to predict 90-day to 2-year mortality. Holdout validation showed AUCs of 0.825, 0.805, 0.779, and 0.766, with risk indices 99% correlated to observed mortality.
Impact: Provides an objective, validated risk tool aligned with continuous organ distribution, potentially standardizing urgency assessment and improving equity.
Clinical Implications: Supports transparent prioritization on waitlists, informs timing of transplant vs. durable MCS, and may harmonize center-level practices using a common risk index.
Key Findings
- Developed and validated CHARM mortality models at 90 days, 180 days, 1 year, and 2 years in 4,176 waitlisted patients.
- AUCs: 0.825 (90d), 0.805 (180d), 0.779 (1y), 0.766 (2y); risk indices 99% correlated with observed mortality.
- Key predictors included BNP, creatinine, sodium, AST, albumin, bilirubin, prior surgeries/transplant, ECMO/mechanical support, ICD, ventilator use.
Methodological Strengths
- Large national registry with contemporary cohort; multi-horizon mortality endpoints.
- Holdout validation demonstrating discrimination and calibration; clinically interpretable predictors.
Limitations
- Retrospective modeling may be affected by unmeasured confounding and center effects.
- External prospective validation and impact analyses on allocation decisions are needed.
Future Directions: Prospective external validation across networks; integration into allocation algorithms and decision-support; assessment of equity and outcome impacts post-implementation.
BACKGROUND: Currently, there is no mathematical model used nationally to determine the medical urgency of patients on the heart transplant waitlist in the United States. While the current organ distribution system accounts for many patient factors, a truly objective model is needed to more reliably stratify patients by their medical acuity. OBJECTIVES: The aim of the study was to develop risk scores (Colorado Heart failure Acuity Risk Model [CHARM] score) to predict mortality in adults waitlisted for heart transplant. METHODS: Risk scores were based on multivariable logistic regression models with mortality endpoints at 90 days, 180 days, 1 year, and 2 years. The models included serology data and patient history variables from waitlisted patients (N = 4,176) within the Scientific Registry of Transplant Recipients database from January 1, 2017, to September 2, 2023.
3. Treatment of prehypertension among adults with HIV.
In 250 virally suppressed adults with HIV and prehypertension in Haiti, amlodipine 5 mg reduced mean SBP by 5.9 mmHg and DBP by 5.5 mmHg vs. control over 12 months, and lowered incident hypertension (5.6% vs 23.0%; HR 0.18; 95% CI 0.07–0.47). Viral suppression and serious drug-related adverse events did not differ; acceptability was high among patients and providers.
Impact: Challenges current threshold-based treatment in low-resource settings by demonstrating safety and efficacy of early pharmacologic therapy in PWH.
Clinical Implications: Programs caring for adults with HIV in resource-limited settings could consider earlier BP treatment to prevent progression to hypertension, integrating simple regimens like amlodipine without compromising HIV control.
Key Findings
- Amlodipine 5 mg reduced mean SBP by −5.9 mmHg (95% CI −8.8 to −3.0) and DBP by −5.5 mmHg (95% CI −7.9 to −3.2) vs control at 12 months.
- Incident hypertension occurred in 5.6% (intervention) vs 23.0% (control); HR 0.18 (95% CI 0.07–0.47).
- No differences in viral load suppression or drug-related serious adverse events; high acceptability in qualitative assessments.
Methodological Strengths
- Randomized clinical trial with pre-specified primary outcome and trial registration (NCT04692467).
- Pragmatic design in a resource-limited setting; clinically relevant incident hypertension endpoint.
Limitations
- Unblinded design may introduce performance bias; single-country setting may limit generalizability.
- Exclusion of patients with diabetes or kidney disease limits applicability to all PWH.
Future Directions: Head-to-head comparisons of agents, cost-effectiveness analyses, and multicountry trials to inform guideline thresholds for PWH in diverse settings.
OBJECTIVE: Elevated blood pressure (BP), even at prehypertensive levels, increases cardiovascular disease risk among people with HIV (PWH); yet international guidelines in low-income countries recommend treatment initiation at BP at least 140/90 mmHg. We determined the efficacy, feasibility, and acceptability of treating prehypertension in PWH in Haiti. DESIGN: An unblinded randomized clinical trial (enrolled April 2021-March 2022) with 12-month follow-up. SETTING: GHESKIO Centres, Port-au-Prince, Haiti. PARTICIPANTS: Two hundred fifty adults with HIV with prehypertension (SBP 120-138 or DBP 80-89) not on medication, aged 18-65 years, virally suppressed, and without pregnancy, diabetes, or kidney disease. INTERVENTION: Participants were randomized to treatment (amlodipine 5 mg) or control (no amlodipine unless two BP ≥140/90 mmHg).