CC BY-NC-ND 4.0 · Indian J Cardiovasc Dis Women WINCARS 2021; 06(01): 027-032
DOI: 10.1055/s-0040-1709957
Original Article

Factors Influencing Survival Outcomes in Patients with Left Ventricular Dysfunction after Coronary Revascularization

Rama Kishore Yalampati
1  Department of Cardiology, NIMS, Hyderabad, Telangana, India
,
N Lalitha
1  Department of Cardiology, NIMS, Hyderabad, Telangana, India
,
Naveen Kumar Murki
1  Department of Cardiology, NIMS, Hyderabad, Telangana, India
› Author Affiliations
 

Abstract

Background Outcomes in patients with left ventricular (LV) dysfunction after coronary revascularization are influenced by multiple factors; however, it is difficult to compare a direct relationship between LV dysfunction and mortality due to the presence of confounding variables, so we attempted to observe the influence of risk factors on outcomes in severe LV dysfunction patients after revascularization and delineate if any of them have an effect on one-year mortality of such patients.

Methodology This is a single center prospective study, where the studied population were severe LV dysfunction patients who underwent percutaneous transluminal coronary angioplasty (PTCA) and followed-up for one year and at the end of one year, impact of gender, age, type 2 diabetes mellitus (DM), hypertension (HTN), obesity, chronic kidney disease (CKD), cerebrovascular accident (CVA), hypothyroidism, smoking and alcohol on one-year mortality and MACE (major adverse cardiovascular events), which included reinfarction (nonfatal), recurrence of angina, repeat percutaneous intervention (PCI) or coronary artery bypass grafting (CABG) and heart failure. The above factors were analyzed and statistically approached to observe the impact of those risk factors on one-year mortality and determine whether the timing and mode of revascularization, and number of coronary arteries involved, had any influence on mortality or MACE events. By comparing different parameters of the study with respect to mortality, a regression analysis was made at the end of one year

Results As many as 152 patients of severe LV dysfunction (ejection fraction < 30%) were enrolled in the study, among which 115 (75.6%) patients were males, and 37 patients were females (24.3%), with a mean age of 57.6 years; 89 (58.5%) patients were hypertensive, 80 (52.6%) patients were diabetics, 42 (27.6%) patients were smokers, 20 (13.1%) patients were alcoholics, 9 (5.9%) had CKD, one (0.6%) patient had hypothyroidism and one (0.6%) patient had a history of CVA; 46 (30.2%) patients presented with acute coronary syndrome (ACS) and 106 (69.7) patients had chronic stable angina (CSA); 144 (94.7%) patients underwent PTCA (percutaneous transluminal coronary angioplasty), while eight (5.2%) patients underwent CABG. At the end of one year, mortality was six patients (3.94%). At the end of one year, regression analysis was done for all the confounding variables by observing their influence on the MACE or mortality; none of them showed statistically significant influence (p > 0.05).

Conclusion At the end of one year, after revascularization in patients with severe LV dysfunction, no significant relationship could be ascertained between the mortality or MACE events and gender, age, DM, HTN, CKD, and alcohol or smoking. MACE or mortality may be attributed directly to LV dysfunction itself, and the observed mortality was higher than that of normal LV Function. Hence, in our study, LV dysfunction is the cause of mortality in the study population but not the other confounding variables.


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Introduction

Outcomes in patients with left ventricular (LV) dysfunction after coronary revascularization are influenced by multiple factors. Myocardial stunning and hibernation can occur as a result of LV dysfunction, mostly ischemic in nature. Several hours after myocardial ischemia, contractile dysfunction persists, but then full functional recovery occurs, which may probably be due to myocardial stunning.[1] Percutaneous coronary intervention (PCI) and stenting gives symptomatic relief and improvement in outcomes because of LV remodeling reversal. Concept of the viable myocardium led to the selection of patients with LV dysfunction, which helps in patient selection for coronary revascularization. This aids in categorizing patients into LV dysfunction with scarred myocardium and LV dysfunction with ischemic but viable myocardium.[2] If imaging studies are performed, after revascularization, areas that are associated with functional recovery are the regions that exhibit a reduction in both myocardial blood flow and fluorodeoxyglucose (FDG) uptake (scarred myocardium). Areas with intact FDG uptake or enhanced uptake, despite poor myocardial perfusion, are usually due to hibernating myocardium.[3] Thus revascularization in severe LV dysfunction patient may be of benefit and may have implications on the outcome.[4]

So, through this study, we attempted to observe the influence of risk factors on outcomes in severe LV dysfunction patients after revascularization and delineate if any of them have an effect on one-year mortality of such patients.


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Aim

To study the impact of various modifiable and nonmodifiable risk factors on outcomes after coronary artery revascularization in patients with severe LV dysfunction.


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Objectives

To study the impact of various risk factors like gender, age, type 2 diabetes mellitus (DM), hypertension (HTN), chronic kidney disease (CKD), cerebrovascular accident (CVA), obesity, hypothyroidism, and smoking and alcoholism on one-year major adverse cardiovascular events (MACE), which included heart failure, reinfarction (nonfatal), recurrence of angina, and repeat PCI or coronary artery bypass grafting (CABG).


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Material and Methods

This is a prospective single-center cohort study done at a tertiary care center for cardiology.

This study was a time-bound study done from January 2017 to December 2018 and all consecutive patients with severe LV dysfunction, who underwent coronary revascularization, were included in the study. As many as 152 patients with severe LV dysfunction (EF < 35%) were enrolled in the study.

Data Collection

After obtaining institutional ethics committee approval, the study sample collection was started in January 2017. Written and informed consent in the local language was obtained from all eligible participants after explaining the objectives and the nature of the study. All the patients with severe LV dysfunction belonging to ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), unstable angina, and silent myocardial ischemia were included in the study. In patients with LV dysfunction, which is of more than 7 days duration, myocardial viability was assessed by perfusion scan and/or echocardiography, and patients with significant viable myocardium were taken up for coronary revascularization. After coronary revascularization by percutaneous transluminal coronary angioplasty (PTCA) with drug-eluting stents or CABG, all patients were started on dual antiplatelet drugs, statins, β-blockers, angiotensin-converting-enzyme (ACE) inhibitors, loop diuretics, and mineralocorticoid receptor antagonists, as per the American Heart Association guidelines.

Patients were followed prospectively for one year and at the end of one year, impact of sex, age, HTN, type 2 DM, CKD, obesity, hypothyroidism, CVA, and smoking and alcohol on one-year MACE, which included heart failure, reinfarction (nonfatal), recurrence of angina and repeat PCI or CABG, were analyzed and statistically approached to observe the impact of those risk factors on one-year mortality and determine whether the timing and mode of revascularization, and number of coronary arteries involved, had any influence on mortality or MACE events. Comparing different parameters of the study with respect to mortality a regression analysis was made at the end of one year.


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Results

As many as 152 patients of severe LV dysfunction (EF < 35%) were included in the study, of which 115 (75.6%) were males, and 37 were females (24.3%), with a mean age of 57.6 years at the time of presentation ([Fig. 1])

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Fig. 1 Gender distribution.

Eighty-nine (58.5%) patients were hypertensive, 80 (52.6%) patients were diabetic, 42 (27.6%) patients were smokers, 20 (13.1%) patients were alcoholics, nine (5.9%) patients had CKD, one (0.6%) patient had hypothyroidism, and one (0.6%) patient had a history of CVA. ([Fig. 2])

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Fig. 2 Distribution of various parameters in study.

Forty-six (30.2%) patients presented with acute coronary syndrome (ACS), and 106 (69.7%) patients presented with chronic stable angina (CSA) ([Fig. 3]).

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Fig. 3 Type of cardiac event at presentation.

As many as 144 (94.7%) patients underwent PTCA, while 8 (5.2%) patients had undergone CABG ([Fig. 4]).

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Fig. 4 Showing type of intervention in the study.

At the end of one year, mortality was six patients (3.94%). At the end of one-year, regression analysis was done for all the confounding variables by observing their influence on the MACE or mortality, and none of them showed statistically significant influence (p > 0.05).

Upon performing the chi-square test for follow-up patients, outcomes versus age, sex, HTN, DM, smoking, alcohol, type of coronary artery disease (CAD), single or multivessel disease and abnormal glomerular filtrate rate (GFR), it was observed that the p-value was not significant for any of the parameters, which imply that LV dysfunction in itself was the intrinsic predictor of outcomes among follow-up patients. Similar results were observed in performing a chi-square test for mortality versus clinical parameters. The findings are elucidated in [Table 1] .

Table 1

Binary logistic regression: mortality versus clinical parameters

Source

DF

Adj dev

Adj mean

Chi-square

p-value

Abbreviation: CAD, coronary artery disease; GFR, glomerular filtration rate; HTN, hypertension.

Regression

9

12.0712

1.34124

12.07

0.209

Age

1

2.3941

2.39411

2.39

0.122

Sex

1

0.9144

0.91439

0.91

0.339

HTN

1

2.3567

2.35672

2.36

0.125

DM

1

2.3238

2.32375

2.32

0.127

Smoking

1

1.2436

1.24362

1.24

0.265

Alcohol

1

0.488

0.48803

0.49

0.485

Type of presentation of CAD

1

0.4365

0.43655

0.44

0.509

Single or multivessel disease

1

0.3049

0.30486

0.3

0.581

GFR abnormal

1

0.0473

0.04734

0.05

0.828

When demographic, laboratory parameters were compared between males and females, none of the parameters had statistical significance except that females had a more severe stage of chronic kidney disease than males with statistical significance. When the type of intervention was compared between males and females, CABG was done in eight patients (5.2%) who were exclusively males and the difference was statistically significant ([Table 2] ).

Table 2

Comparison of demographic, laboratory and parameters comparing males and females

Variable

Males (n = 115)

Female (n = 37)

p-value

Abbreviations: ACS, acute coronary syndrome; CABG, coronary artery bypass grafting; CAD, coronary artery disease; CKD, chronic kidney disease; CSA, chronic stable angina; DM, diabetes mellitus; GFR, glomerular filtration rate; FH, familial hypercholesterolemia; HTN, hypertension; MI, myocardial infarction; PCI, percutaneous coronary intervention; SVD, single vessel disease.

*Severe TVD requiring CABG was seen only in males with statistical significance.

Age (yrs.)

57.20 ± 11.47

58.86 ± 10.71

0.423

HTN

63 (54.8%)

26 (70.3%)

0.079

DM

56 (48.6%)

24 (64.8%)

0.076

SM

41 (35.7%)

1(2.7%)

0.000

Alcoholics

20 (17.3%)

0

FH of CAD

0

0

GFR

78.80 ± 48.82

63.77 ± 39.62

0.062

Hemoglobin (gm. %)

12.78 ± 2.05

11.45 ± 1.77

0.000

CSA

32 (27.8%)

14(37.8%)

0.266

Type of ACS–MI

25 (78.1%)

9(64.2%)

0.348

CKD

87 (75.6%)

29 (78.4%)

0.729

Stage of CKD

Stage 1

1(1.1%)

0

0.315

Stage 2

40(45.9%)

8 (27.5%)

0.062

Stage 3A

23 (26.4%)

6 (20.7%)

0.518

Stage 3B

21 (21.1%)

9(31.03%)

0.479

Stage 4

2 (2.29%)

6(20.7%)

0.017

PCI previous cardiac procedure

21(18.2%)

4(10.8%)

0.233

CABG

8 (6.9%)

0

0.003*

SVD

79 (68.9%)

26 (70.3%)

0.856

Route of procedure–radial

103 (89.5%)

30(81.08%)

0.228

Stent size

2.94 ± 0.32

2.96 ± 0.34

0.753

Stent length

21.54 ± 7.51

21.32 ± 8.82

0.892

In hospital complication

3 (2.6%)

1(2.7%)

0.975

One-year follow-up

14 (12.17%)

6(16.2%)

0.551

When outcomes (both in hospital and at one-year follow-up) were compared between males and females, there was no significant difference between males and females in terms of in hospital complications (p-value 0.97) and at one-year follow-up (p-value 0.55) ([Table 3] ).

Table 3

Comparing the outcomes (both in hospital and one-year follow-up) between males and females

Variables

Males (n = 115)

Female (n = 37)

p-value

In hospital complications

3 (2.6%)

1(2.7%)

0.975

One-year follow-up

14 (12.17%)

6(16.2%)

0.551

Also, the parameters were statistically approached with respect to MACE. It had yielded similar results; however, statistical significance was observed between the occurrence of MACE and type of CAD (p-value 0.028).


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Discussion

CAD is one of the main causes of morbidity and mortality worldwide. LV systolic function has prognostic value in CAD, so assessment of left ventricular ejection fraction (LVEF) should be done in all patients after acute myocardial infarction (AMI). Although reperfusion therapy has been found effective in the reduction of complications of AMI, LVEF impairment is a common consequence of an acute coronary event.

A meta-analysis of 19 studies was performed with a sample size of 4766, in which PCI among patients with LV dysfunction (EF < 40%) and one-year mortality were studied. LV dysfunction patients who underwent PCI had acceptable one-year mortality.[5] This is similar to the findings of our study results. Several studies have compared PCI versus CABG and found that PCI is a noninferior mode of revascularization,[6] which is similar to our study result. Even though studies like BARI2D have highlighted the role of diabetic control in the prevention of MACE in post-PCI patients, our study did not show a statistically significant difference in outcome with respect to DM and MACE in severe LV dysfunction,[7] suggesting that DM has no impact on outcomes in patients with severe LV dysfunction.

Studies showed low eGFR affecting MACE rates in severe LV dysfunction patients undergoing PCI, but our study did not find a statistical significance of low e GFR with outcomes.[8]

Studies have shown no effect of smoking, alcohol, age, sex, HTN, and DM in relation to MACE in postrevascularization patients,[9] which is consistent with our findings.

Limitation

Individual variability in modifiable risk factors and their severity were not compared, and it might be one of the confounding factors.


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Conclusion

From our prospective follow-up cohort study conducted to observe the influence of various parameters on the outcomes of mortality or MACE events in patients with severe LV dysfunction, after revascularization at the end of one year, no significant relationship could be determined between the MACE or mortality and gender, age, HTN, type II DM, CKD, smoking or alcohol. Severe CAD requiring CABG was seen only in males. There was no statistically significant correlation between in-hospital complications or MACE events and males or females at one year of follow-up.

On the other hand, MACE or mortality may be attributed directly to LV dysfunction itself. The association of severe LV dysfunction to one-year mortality was found to be the most influential factor after adjusting for all confounding variables, either single or combined, after applying binomial regression analysis.

Audio File

Audio file for this article is available at https://doi.org/10.1055/s-0041-1727566.


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Conflict of Interest

None declared.


Address for correspondence

Rama Kishore Yalampati, DM
Department of Cardiology, NIMS
Hyderabad, Telangana, 500 082
India   

Publication History

Publication Date:
13 April 2021 (online)

© 2021. Women in Cardiology and Related Sciences. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).

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Fig. 1 Gender distribution.
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Fig. 2 Distribution of various parameters in study.
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Fig. 3 Type of cardiac event at presentation.
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Fig. 4 Showing type of intervention in the study.