Impact of persistent MVO late after STEMI on adverse left ventricular remodelling: a CMR study

Background

Despite successful revascularization at the epicardial level, microvascular obstruction (MVO) appears soon after reperfusion in up to 50% of cases. Early MVO has been solidly associated with adverse resulting cardiac structure and heightened risk of future cardiovascular events. Although clinical and experimental studies demostrated the spontaneous repair of MVO, little is known about the occurrence and implications of persistent MVO late after infarction.

Purpose

We used cardiovascular magnetic resonance (CMR) to characterize the impact of persistent MVO late after reperfused ST-segment elevation myocardial infarction (STEMI) on adverse left ventricular (LV) remodelling (ALVR).

Methods

A prospective registry of 471 STEMI patients underwent CMR 7 [5–10] and 198 [167–231] days post infarction, and MVO (>1 segment) and ALVR (relative increase >15% at follow-up CMR) of LV end-diastolic (LVEDVI) and end-systolic volume indices (LVESVI) were determined.

Results

One-week MVO occurred in 209 patients (44%) and persisted in 30 of these (6%). Most patients with persistent MVO (22/30, 73%) displayed extensive (>2.5% of LV mass) MVO at 1 week. Compared with patients without MVO (n=262, 56%) or with MVO only at 1 week (n=179, 38%), those with persistent MVO at follow-up (n=30, 6%) showed higher rates of ALVR-LVEDVI (22%, 27%, 50% p=0.003) and ALVR-LVESVI (20%, 21%, 53% p<0.001). After adjustment, the extent (% of LV mass) of MVO at follow-up was independently associated with ΔLVEDVI (relative increase, %) (p=0.01) and ΔLVESVI (p=0.03). Compared to a 1:1 matched population of 30 patients with MVO only at 1 week, patients with persistent MVO more frequently displayed ALVR-LVEDVI (12% vs. 50%, p=0.003) and ALVR-LVESVI (12% vs. 53%, p=0.001).

Conclusion

MVO persists in a small percentage of patients in chronic phase after STEMI and exerts deleterious effects in terms of LV remodelling. These findings fuel the need for further research on microvascular injury repair.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by “Instituto de Salud Carlos III” and “Fondos Europeos de Desarrollo Regional FEDER” [grant numbers PI20/00637, PI15/00531, FI18/00320, and CIBERCV16/11/00486] and by Conselleria de Educaciόn – Generalitat Valenciana (PROMETEO/2021/008).

A novel clinical and stress cardiac magnetic resonance score to predict long-term all-cause mortality in patients with known or suspected chronic coronary syndrome

Background

Vasodilator stress cardiac magnetic resonance (stressCMR) has shown robust diagnostic and prognostic value in patients with known or suspected chronic coronary syndrome (CCS). However, it is unknown whether integration of several prognostic stressCMR parameters, such as the ischemic burden (number of segments with first-pass stress-induced perfusion defects -PD-) and left ventricular ejection fraction (LVEF), with clinical variables can improve risk prediction in this population.

Purpose

We aim to explore the usefulness of a clinical-stressCMR score to predict the risk of all-cause mortality in patients with known or suspected CCS submitted to undergo a stressCMR.

Methods

We included 6187 patients in a large prospective multicenter registry (mean age 65.18±11.51 years, 37.3% female) which underwent stressCMR for known or suspected CCS. Several clinical and stressCMR variables were collected, such as LVEF, end-diastolic and end-systolic volume indices, ischemic burden and segments with necrosis (with late gadolinium enhancement imaging).

Results

During a mean and median follow-up of 5.85±3.82 years we registered 682 (11%) all-cause deaths. Several clinical and all stressCMR variables were associated with all-cause mortality in univariate analysis. However, the only independent predictors of all-cause mortality in multivariate analysis were age (HR 1.07 [1.06–1.08] per year, p<0.001), male sex (HR 1.36 [1.15–1.61], p<0.001), diabetes mellitus (HR 1.6 [1.37–1.87], p<0.001), LVEF (0.98 [0.97–0.98] per %, p<0.001) and ischemic burden (HR 1.04 [1.02–1.06] per segment with stress-induced PD, p=0.001). By means of the chi-square increase at each step of the stepwise multiparametric Cox regression we created a clinical-stressCMR score that included these variables (age, male sex, diabetes mellitus, LVEF and ischemic burden) kept in their continuous state if possible. This score showed a good performance to predict all-cause mortality (area under the curve = 0.716 [0.697–0.735], p<0.001). Dividing the population into quintiles according to the clinical-stressCMR score allowed for a stratification of the annualized risk of all-cause mortality (0.39%/year, 0.94%/year, 1.62%/year, 2.63%/year and 3.83%/year, respectively; log-rank 420.33 and p<0.001 for Kaplan-meier curves).

Conclusions

A novel clinical-stressCMR, which includes clinical (age, male sex, and diabetes mellitus) and stressCMR (LVEF and ischemic burden) variables, can provide robust prediction and stratification of the risk of all-cause mortality in a population of patients with know or suspected CCS.

Figure 1. Clinical-stress CMR score

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study was funded by “Instituto de Salud Carlos III” and “Fondos Europeos de Desarrollo Regional FEDER” (PIE15/00013, PI17/01836, and CIBERCV16/11/00486 grants) and by Generalitat Valenciana (GV/2018/116).

Opposite effects of myocardial stretch and verapamil on the complexity of the ventricular fibrillatory pattern: an experimental study

An experimental model is used to analyze the effects of ventricular stretching and verapamil on the activation patterns during VF. Ten Langendorff-perfused rabbit hearts were used to record VF activity with an epicardial multiple electrode before, during, and after stretching with an intraventricular balloon, under both control conditions and during verapamil (Vp) infusion (0.4-0.8 mumol). The analyzed parameters were dominant frequency (FrD) spectral analysis, the median (MN) of the VF intervals, and the type of activation maps during VF (I = one wavelet without block lines, II = two simultaneous wavelets with block lines, III = three or more wavelets with block lines). Stretch accelerates VF (FrD: 22.8 +/- 6.4 vs 15.2 +/- 1.0 Hz, P < 0.01; MN: 48 +/- 13 vs 68 +/- 6 ms, P < 0.01). On fitting the FrD time changes to an exponential model after applying and suppressing stretch, the time constants (stretch: 101.2 +/- 19.6 s; stretch suppression: 97.8 +/- 33.2 s) do not differ significantly. Stretching induces a significant variation in the complexity of the VF activation maps with type III increments and type I and II decrements (control: I = 17.5%, II = 50.5%, III = 32%; stretch: I = 7%, II = 36.5%, III = 56.5%, P < 0.001). Vp accelerates VF (FrD: 20.9 +/- 1.9 Hz, P < 0.001 vs control; MN: 50 +/- 5 ms, P < 0.001 vs control) and diminishes activation maps complexity (I = 25.5%, II = 60.5%, III = 14%, P < 0.001 vs control). On applying stretch during Vp perfusion, the fibrillatory process is not accelerated to any greater degree. However, type I and II map decrements and type III increments are recorded, though reaching percentages similar to control (I = 16.5%, II = 53%, III = 30.5%, NS vs control). The following conclusions were found: (1) myocardial stretching accelerates VF and increases the complexity of the VF activation pattern; (2) time changes in the FrD of VF during and upon suppressing stretch fit an exponential model with similar time constants; and (3) although stretching and verapamil accelerate the VF process, they exert opposite effects upon the complexity of the fibrillatory pattern.