Sudden cardiac death risk factors

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Cardiac Arrest or VT/VF Occurring As A Complication of STEMI

VT/VF and/or sudden death may occur early after the presentation of STEMI symptoms (<48 hours) and late after presentation (>48 hours) . The occurrence of both early and late VT/VF is associated with higher mortality. In a large contemporary analysis which included 5,745 high risk patients undergoing primary PCI in the APEX AMI trial, about 6% of patients developed VT/VF. the majority of the cases (64%) occurred during cardiac catheterization, and 90% of cases occurred withing 48 hours of presentation of STEMI symptoms. 90 day mortality was higher in those patients who sustained VT/VF (23.2% vs 3.6%, a multivariate hazard ratio of 3.63). Mortality was higher among those patients with late VT/VF (33.3%) vs early VT/VF (17.2%). It should also be noted that while many of the subsequent deaths in patients with VT/VF were due to sudden cardiac death, sudden cardiac death accounted for less than 50% of the mortality in VT/VF patients. Although VT/VF was not associated with one year mortality in the Primary Angioplasty and Myocardial Infarction (PAMI) trials , this is likely due to the fact that the PAMI population was of lower risk and had a lower one year mortality (4.5% in PAMI vs 23.2% reported in the present study).

Multivariate Predictors of Early VT/VF in the Setting of STEMI

1. Pre-PCI thrombolysis in MI (TIMI) flow grade 0 (HR, 2.94; 95% CI, 1.93-4.47)
2. Inferior infarction (HR, 2.16;95%CI, 1.58-2.93)
3. Total baseline ST deviation (HR, 1.39;95%CI, 1.19-1.63)
4. Creatinine clearance (HR, 0.88; 95% CI, 0.83-0.94)
5. Killip class greater than I (HR, 1.88;95%CI, 1.29-2.76)
6. Baseline systolic blood pressure (HR, 0.92;95%CI, 0.87-0.98)
7. Body weight (HR, 1.16; 95% CI, 1.04-1.29)
8. baseline heart rate greater than 70/min (HR,1.10;95%CI, 1.01-1.20)

c index for the model = 0.75

Multivariate Predictors of Late VT/VF in the setting of STEMI

1. Systolic blood pressure (HR, 0.83; 95% CI, 0.76-0.91)
2. ST resolution less than 70% (HR, 3.17; 95% CI,1.60-6.28)
3. Baseline heart rate greater than 70/min (HR, 1.20; 95% CI, 1.08-1.33)
4. Total baseline ST deviation (HR, 1.43; 95% CI, 1.14-1.79)
5. Post-PCI TIMI flow less than grade 3(HR, 2.09;95%CI, 1.24-3.52)
6. Pre-PCI TIMI flow grade 0(HR, 2.12;95%CI, 1.20-3.75),
7. Blockers less than 24 hours (HR, 0.52; 95% CI, 0.32-0.85)

c index for the model = 0.74

Multivariate modeling did demonstrate that about one-fifth of the variability in 90 day mortality was explained by VT/VF. It should be noted that many patients did not undergo left ventriculography in this study. When left ventricular ejection fraction was available and included in the multivariate model, it failed to be statistically significant. This is likely because it was co-linear with other variables such as Killip class, infarct location, TIMI flow and pulse.

Clinical Implications

Those patients with < TIMI grade 3 flow and < 70% ST resolution following PCI are at higher risk of VT/VF and should be monitored more carefully in an ICU or telemetry setting.

VT/VF Complicating AMI (both STEMI and NSTEMI taken together)

While the prior information focuses on STEMI, a study by Piccini et al of 9,000 patients focused on both STEMI as well as NSTEMI who underwent PCI within 24 hours of acute MI in the New York State Coronary Angioplasty Reporting System database . 5.2% of patients sustained VT/VF and mortality was over 4 times higher among patients with VT/VF (16.3% vs 3.7%). Operator reported successful PCI was associated with a lower subsequent mortality associated with VT/VF. The following were identified as independent predictors of early VT/VF:

1. Cardiogenic shock (OR, 4.10; 95%CI, 3.20-5.58)
2. Heart failure (OR, 2.86;95% CI, 2.24-3.67)
3. Chronic kidney disease (OR, 2.58; 95% CI, 1.27-5.23)
4. Early presentation (6 hours from symptom onset; OR, 1.46; 95% CI, 1.18-1.81)

The following variables were found to be independently associated with a lower risk of VT/VF:

1. History of hypertension (OR, 0.81; 95% CI, 0.65-1.00)
2. Lleft circumflex as infarct artery (OR, 0.80; 95% CI, 0.65-0.99)
3. Diabetes mellitus (OR,0.57; 95% CI, 0.42-0.78)
4. Higher left ventricular ejection fraction (every 5% increment; OR, 0.93; 95% CI, 0.91-0.96)