MYOCARDIAL INFARCTION;

NEW ONSET HEART FAILURE AFTER MI. ITS FREQUENCY AND FACTORS CONTRIBUTING IT

Abstract

Objectives: To determine the frequency of new onset heart failure after acute
myocardial infarction and factors contributing it. Methods: A total of 228 patients were studied
for occurrence of new onset clinical heart failure within24 hours after admission with an
acute Myocardial Infarction. Clinical parameters were used to diagnose heart failure. Various
risk factors were analyzed which contributed to occurrence of heart failure after MI. Patients
undergoing primary angioplasty were not included into this study as medical thrombolysis was
the most common mode of therapy (in >90% of patients). Results: Among the 228 patients
studied 77.2 %( 176) were males and 22.8 %(52) were females. Mean age of the population
was 56.3(±12.1) years. Women were relatively older on presentation as compared to men
(mean age 58.9±10.9yr vs 55.5±12.3yr). Similarly mean age for NSTEMI was higher as
compared to STEMI (58.59±11.1 vs 54.2±12.6yr.). A total of36.8 %( 84) patients exhibited
clinical signs of heart failure within24 hours of their admission. These patients tend to be older
than patients without HF (mean age 60±11years vs 54±12 years). Females after MI showed a
greater frequency for going into HF as compared to males (42.3% vs 35.2% respectively). Now
regarding the association of HF with various factors it was seen that, having a previous history
of MI was found to be the strongest factor associated with occurrence of HF, with HF being
nearly three times more common in these patients (i.e. 73% vs 26.1%, p value < 0.05). The
current type of MI on presentation also showed a direct relationship with HF, being highest in
patients with NSTEMI (i.e. up to 50 %) followed by AWMI (35.5%) and lowest in inferior wall MI (p
value < 0.05). Diabetes, hypertension and smoking also showed a higher but statistically nonsignificant
relationship with HF development (41.2% vs 34.3%, 41% vs 32.2% and 44% vs 32%
respectively p value > 0.05). The blood pressure on presentation however was significantly
associated with HF in these patients. Patients having high BP (> 140/80) on presentation
depicted an overall higher incidence of HF as compared to patients having BP equal to or less
than 140/80 (45.2% vs 31.3% p value < 0.05). Conclusion: Heart failure is a fairly common
entity after acute MI, being the commonest in patients suffering an NSTEMI. Previous history of
an MI showed to be the strongest coexisting factor associated with HF.