Hughes, Alun D

BACKGROUND: The impact of life-course blood pressure (BP) trajectories on later-life focal left ventricular (LV) fibrosis by late gadolinium enhancement (LGE) remains elusive. METHODS: MyoFit46 prospectively recruited ≈500 participants from a 1946 birth cohort for a cardiovascular magnetic resonance scan at 77 years, assessing LV LGE calculated using the 3-SD method or 5-SD method. Systolic BP (SBP) and diastolic BP were recorded at 36, 43, 53, 63, 69, and 77 years. For each participant, annual rates of BP change (steepness) and area under the BP trajectory (cumulative burden) for each age interval were calculated using mixed-effects models. Associations between life-course BPs and LGE were tested using generalized linear models, adjusted for antihypertensives, demographics, lifestyle, and comorbidities. Time-to-event associations between LGE and incident major adverse cardiovascular event (hospitalizations for coronary artery disease, stroke, heart failure, and atrial/ventricular arrhythmias; n=29) were also evaluated. RESULTS: Among 472 participants (54% male), each 10 mm Hg greater individual SBPs at 36 to 69 years were associated with 6% to 11% greater LV LGE calculated using the 3-SD method (all P ≤0.033), whereas each 10 mm Hg sustained greater SBPs on any age interval from 36 to 69 associated with 16% to 24% greater LGE calculated using the 3-SD method at 77(all P ≤0.005), independent of SBP at 77 years. Each 1 mm Hg/y steeper SBP rise during age intervals 36 to 43, 43 to 53, and 53 to 63 was associated with 6% to 12% greater LGE calculated using the 3-SD method at 77 years. LGE presence was associated with greater major adverse cardiovascular event rates (hazard ratio, 2.5 [95% CI, 1.2–5.2]). CONCLUSIONS: Higher life-course BPs, cumulative burden, and steeper increases were associated with greater older-age LV LGE, which was linked to incident major adverse cardiovascular events. BP trajectories, beyond single-point BP measurements, warrant further investigation as tools to guide BP management strategies.

BACKGROUND: Elevated blood pressure (BP) is a major contributor to coronary artery disease. We explored the impact of life-course BP on later-life normalized stress myocardial blood flow (sMBF N ) and myocardial perfusion reserve by cardiovascular magnetic resonance (CMR). METHODS: MyoFit46 prospectively recruited ≈500 National Survey of Health and Development 1946 birth cohort participants, aged ≈77 years, to undergo stress perfusion and late gadolinium enhancement CMR. Systolic (SBPs) and diastolic BPs were recorded at 36, 43, 53, 63, 69, and 77 years. For each participant, the annual rates of BP change (steepness of BP increase) and area under the BP trajectory curve (cumulative life-course BP burden) were derived using mixed-effects models. The associations between BP measures and CMR metrics were tested using generalized linear and additive models, adjusted for antihypertensive use, demographics, lifestyle choices, and comorbidities. Cross-sectional associations between CMR metrics and major adverse cardiovascular events (myocardial infarction, stroke, and heart failure) were also tested. Mediation analyses explored the mechanistic pathways linking life-course BPs, myocardial perfusion, and myocardial fibrosis. RESULTS: Among 459 included MyoFit46 participants, each 10 mm Hg higher SBP at 36 to 69 years was associated with 3% to 6% lower sMBF N by CMR at 77 years. At 43 to 63 years, as SBPs rose from 120 to 140 mm Hg, sMBF N was 18% to 24% lower. Having a sustained higher SBP by 10 mm Hg from 36 to 77 years was associated with 11% (95% CI, 8–14) lower sMBF N at 77 years. Each 1 mm Hg/y steeper SBP rise during age intervals 36 to 43, 43 to 53, 53 to 63, and 63 to 69 years was associated with 2% to 6% lower sMBF N at 77 years, associations not conditional on baseline or final BPs in each age interval. Associations may be clinically relevant as each 1% lower sMBF N was associated with 3% higher odds of major adverse cardiovascular events. sMBF N mediated ≈20% to ≈40% of the associations between life-course SBPs and late gadolinium enhancement at 77 years. Results were similar for diastolic BP, myocardial perfusion reserve, or sMBF (not normalized). CONCLUSIONS: Higher life-course BPs, steeper increases, and greater cumulative BP burden associate with lower myocardial perfusion by CMR at 77 years, which can be linked with higher odds of major adverse cardiovascular events and greater myocardial fibrosis burden. This underscores the importance of early life BP screening and guiding hyperetension treatment based on longitudinal BP trajectories (rather than relying solely on cross-sectional BPs). REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT05455125.

Background Constant flow and concentration CO2 has previously been efficacious in attenuating ventilatory oscillations in periodic breathing (PB) where oscillations in CO2 drive ventilatory oscillations. However, it has the undesirable effect of increasing end-tidal CO2, and ventilation. We tested, in a model of PB, a dynamic CO2 therapy that aims to attenuate pacemaker-induced ventilatory oscillations while minimising CO2 dose. Methods First, pacemakers were manipulated in 12 pacemaker recipients, 6 with heart failure (ejection fraction (EF)=23.7±7.3%) and 6 without heart failure, to experimentally induce PB. Second, we applied a real-time algorithm of pre-emptive dynamic exogenous CO2 administration, and tested different timings. Results We found that cardiac output alternation using pacemakers successfully induced PB. Dynamic CO2 therapy, when delivered coincident with hyperventilation, attenuated 57% of the experimentally induced oscillations in end-tidal CO2: SD/mean 0.06±0.01 untreated versus 0.04±0.01 with treatment (p<0.0001) and 0.02±0.01 in baseline non-modified breathing. This translated to a 56% reduction in induced ventilatory oscillations: SD/mean 0.19±0.09 untreated versus 0.14±0.06 with treatment (p=0.001) and 0.10±0.03 at baseline. Of note, end-tidal CO2 did not significantly rise when dynamic CO2 was applied to the model (4.84±0.47 vs 4.91± 0.45 kPa, p=0.08). Furthermore, mean ventilation was also not significantly increased by dynamic CO2 compared with untreated (7.8±1.2 vs 8.4±1.2 L/min, p=0.17). Conclusions Cardiac pacemaker manipulation can be used to induce PB experimentally. In this induced PB, delivering CO2 coincident with hyperventilation, ventilatory oscillations can be substantially attenuated without a significant increase in end-tidal CO2 or ventilation. Dynamic CO2 administration might be developed into a clinical treatment for PB. Trial Registration number ISRCTN29344450.