Cardiovascular Journal of Africa: Vol 28 No 3 (May/June 2017)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 3, May/June 2017

AFRICA

189

many investigators. Poli and colleagues found that MBG score

and ST-segment elevation recovery after successful primary PCI

were associated with the degree of early and late recovery of LV

function.

The ability of MBG score to predict survival rate was studied

by Stone

et al

They found a strong relationship between survival

rate and MBG score after primary or rescue PCI. Among their

study group, one-year survival rate was 6.8% in patients with

normal MBG scores, 13.2% in patients with reduced MBG, and

18.3% in patients with absent blush.

Bolognese

et al

. found that microvascular dysfunction, as

assessed by intracoronary myocardial contrast echo score index,

was able to predict the occurrence of LV remodelling as well

as unfavourable long-term outcome.

De Luca and colleagues

found that MBG score was an independent predictor for

one-year mortality after primary PCI for STEMI patients

presenting with signs of heart failure.

The value of time to primary PCI was studied by Soon and

colleagues. They found that symptom-to-balloon not door-to-

balloon time was a significant independent predictor of short-

and medium-term mortality rates and major adverse cardiac

events.

Symptom-to-balloon time was found by Hahn

et al

. to

be associated with infarct transmurality.

Why do some STEMI patients, even after successfully

performed primary PCI, have poor myocardial perfusion with

MBG 0 or 1? In an attempt to answer this question, Prasad

al.

studied the effect of prolonged ischaemia on MBG score

after primary PCI. Their main finding was that delayed primary

PCI was associated with greater injury to the microcirculation

and impaired myocardial perfusion. They also found that

patients presenting four hours after symptom onset had a higher

incidence of MBG 0 and 1, compared to those presenting within

two hours.

Several mechanisms may lead to impaired myocardial

perfusion in patients with prolonged ischaemic time. These

include endothelial dysfunction and damage, interstitial and

cellular haemorrhage/oedema, formation of micro-thrombi

within themicro-vessels, and an increase in thrombus organisation

with time, which lessens its responsiveness to antiplatelet and

anticoagulant therapies and increases the probability for distal

macro- or micro-embolisation.

21,22

Earlier researchers found that many factors may influence

the process of LV remodelling, such as patency of the infarct-

related artery,

treatment with angiotensin converting enzyme

(ACE) inhibitors and/or beta-blockers,

and baseline BNP

concentrations.

Treatment with renin–angiotensin–aldosterone

blockers after MI was found to ameliorate the process of LV

remodelling in experimental models

as well as in humans.

3,27

In our study, which was a single-centre study, all our patients

were treated in a similar way. This may explain why symptom-to-

balloon time, symptom-to-door time and MBG score were the

only significant predictors for LV remodelling. Mean door-to-

balloon time was 46.1

11.8 minutes in the whole study group

and it did not differ significantly between the two groups. It also

did not correlate with increase in LVEDV. The door-to-needle

time was also fairly similar in the whole study group, probably

since the study was conducted in a single centre with the same

treatment strategy applied to all patients.

The longer symptom-to-door time in the remodelling group

made the symptom-to-balloon time significantly longer as

well. This may have been caused by many factors, including

lack of public awareness of the symptoms of STEMI and the

importance of seeking medical help timeously, the small number

of centres capable of performing primary PCI, the large distance

between these centres and primary health centres, and the huge

traffic problem in a developing country such as Egypt.

Limitations of this study are that it was carried out in a single

centre, and recording the time of onset of symptoms is totally

subjective, which may make measuring of symptom-to-door

time inaccurate.

Conclusion

Our study showed that after successfully performed primary

PCI for STEMI patients, symptom-to-door time, symptom-to-

balloon time and MBG were the only significant predictors of

LV remodelling. Efforts must be made to reduce symptom-to-

door time, including promoting health awareness of cardiac

symptoms, educating primary healthcare providers, and

improving the ambulance system.

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