Non-Specific Intra-Ventricular Conduction Delay - A quick-lit-review

The clinical/prognostic significance of a non-specific intra-ventricular conduction delay

1. Non-Specific Intra-Ventricular
Conduction Delay (nsIVCD).
A 'quick-lit-review'.
BY SIMON MARK DALEY (2019)
The clinical/prognostic significance of a

2. "nonspecific intraventricular conduction delay is defined by a QRS
duration >110ms in adults, >90ms in 8-16yr olds and >80ms in under 8
year olds. without meeting the criteria for RBBB or LBBB."
DEFINITION AS PER AHA/ACC/HRS (2009);
These conduction delays may be observed after large myocardial infarctions, in which the necrotic
area may cause non-specific conduction disturbances.
Delays may be due to myocardial fibrosis, amyloidosis, cardiomyopathy or hypertrophy.
NON-SPECIFIC INTRA-VENTRICULAR
CONDUCTION DELAY (nsIVCD).

3. NON-SPECIFIC INTRA-VENTRICULAR
CONDUCTION DELAY (nsIVCD).
DEFINITION AS PER "LIFE IN THE FAST LANE.COM" (2019);
QRS interval >120ms;
Absence of a supraventricular rhythm.
Most commonly this will be due to bundle branch block or hypertrophy.

There are a variety of causes for an IVCD, but a non-specific IVCD can only be defined in their absence;

.

Fascicular (LAFB & LPFB) and bundle branch blocks;
Left and right ventricular hypertrophy;
Bi-ventricular enlargement;
Dilated cardiomyopathy;
Wolf Parkinson White syndrome (WPW) (also delta wave);
Brugada syndrome;
Arrhythmogenic right ventricular dysplasia (ARVD) (also
epsilon waves).
Hyperkalaemia;
Sodium channel blocker toxicity (TCA overdose) (also +ve R wave in aVR).
(2 life-threatening causes that should be excluded as a priority).

4. Quick-lit-review for the term "clinical significance of non-
specific intra-ventricular conduction delay" performed.

"Intraventricular
Conduction Delay in a
Standard 12-Lead
Electrocardiogram as a
Predictor of Mortality in
the General Population."
Aro et al
(2011).
"Prognostic implications
of intraventricular
conduction delays in a
general population: The
Health 2000 Survey."
Tiosano et al
(2016).
"Prevalence of
ventricular conduction
blocks in the resting
electrocardiogram in a
general population: The
Health 2000 Survey."
Haataja et al
(2016).
"Prognostic Significance
and Clinical Utility of
Intraventricular
Conduction Delays on
the Preoperative
Electrocardiogram."
Richardson et al
(2018).
"A Three-Decade
Survival Analysis of
Intraventricular
Conduction Delay in
Adults Without Ischemic
Heart Disease."
Haataja et al
(2014).
5 studies were identified;

5. ARO ET AL (2011);
10,957 Finnish subjects aged 30-60years.
Data obtained from screening between 1966-1972.

Non-specific IVCD (nsIVCD) was associated with increased mortality and a markedly increased risk of sudden
arrhythmic death in the general population. This was independent of factors that may be expected to predict
cardiac death and risk of sudden arrhythmic death increased 3-fold even after multivariant adjustment.

In patients with suspected coronary artery disease (CAD), nsIVCD was an independent predictor of cardiac
death and non-fatal myocardial infarction (MI).

In patients with suspected acute coronary syndrome (ACS), nsIVCD predicted in-hospital and 1 year mortality.

In the general population without BBB, a change in QRS delay from <110ms to >130ms was associated with an
1.8 fold increase in risk of cardiovascular death.

In hypertensive patients with left ventricular hypertrophy, nsIVCD predicted all cause and cardiovascular
mortality and identified patients at risk of sudden cardiac death.

6. HAATAJA ET AL (2014);
6,299 Finnish subjects.
8 year follow-up.

In the general population, nsIVCD (as well as left bundle
branch block and incomplete right bundle branch block) was
associated with increased risk for all cause and cardiovascular
mortality.

7. TIOSANO ET AL (2016);
2,465 Isreali subjects between 1976-1982.
30 year follow-up.

When controlled for gender, age and BMI, nsIVD was not
associated with increased mortality in individuals without
ischaemic heart disease.

8. HAATAJA ET AL (2016);
6,315 Finnish subjects.


nsIVCD was associated with CAD/angina (22.9% of patients).

nsIVCD was associated with heart failure (11.4% of patients).

9. RICHARDSON ET AL (2018);
152,479 non-cardiac surgical patients.
Retrospective analysis.
3.3% of subjects had nsIVCD.

ECGs with conduction delays did not confer an increased risk
of post-operative death.

Risk of post-operative MI was not significantly increased
among those with conduction delays, compared with normal
ECGs.

10. 3 out of 4 studies
(including the largest
cohort) indicated that
nsIVCD was a predictor of
mortality - cardiac & non-
cardiac.
CONCLUSIONS;

At 30yr follow-up &
when adjusted for
controls, nsIVCD was
not associated with
increased mortality in
those without IHD.
There is no
increased surgical
risk in individuals
with nsIVCD.

These apparently contradictory findings can perhaps be reconciled by interpreting that nsIVCD
is a predictor of IHD, as well as mortality for those with IHD only. It is more difficult to
interpret the significance of nsIVCD in those without IHD, although the largest cohort study
found increased mortality and sudden arrhythmic death in the general population with nsIVCD.

11. IMPLICATIONS FOR CLINICIANS;

The threshold for testing
those at risk of IHD/CAD
should be lower in those
with nsIVCD.
Testing threshold
Individuals with nsIVCD
do not need any specific
surgical considerations.
Surgery
Individuals with nsIVCD but
with a proven absence of
IHD/CAD may still have
greater risk of death
therefore appropriate
clinical judgement should
be applied on a case by
case basis.
Absence of
IHD/CAD
Individuals with nsIVCD
should have their risk
factors aggressively
controlled, as the largest
cohort study suggests
that they are at greater
risk of IHD/CAD and
sudden death.
Risk factors

12. REFERENCES;
https://litfl.com/interventricular-conduction-delay-qrs-widening/
https://ecgwaves.com/ecg-topic/nonspecific-intraventricular-conduction-delay-defect/
https://www.tandfonline.com/doi/abs/10.3109/07853890.2014.985704?
needAccess=true&journalCode=iann20
https://www.sciencedirect.com/science/article/abs/pii/S0002914918301140
https://www.sciencedirect.com/science/article/pii/S0002934316305654
https://www.ahajournals.org/doi/full/10.1161/CIRCEP.111.963561
https://www.sciencedirect.com/science/article/pii/S0167527312006353