Keywords:
Outcomes analysis, MR, Cardiac, Cardiac Assist Devices
Authors:
G. Pontone1, D. Andreini1, A. Solbiati1, M. Guglielmo1, S. Mushtaq1, A. Baggiano1, V. Beltrama1, C. Rota1, A. I. Guaricci2, M. Pepi1; 1Milan/IT, 2Foggia/IT
Methods and Materials
The study population consisted of 515 consecutive patients with clinical history of chronic heart failure according to the Framingham Criteria (10) and referred to our hospital to be evaluated for ICD implantation in primary prevention between January 2011 and December 2013.
Exclusion criteria were unstable angina (n= 30),
decompensated heart failure (n= 28),
acute myocarditis (n= 3),
severe claustrophobia (n= 15),
presence of an implantable device (n= 11),
estimated glomerular filtration rate ≤30 ml/min (n= 12),
and contraindication to gadolinium contrast agent (n= 7).
According to the exclusion criteria,
the final study population comprised 409 patients (mean age: 64±12; men: 331) (Figure 1).
All patients underwent:
1) Screening Procedure and Enrolment
2) TTE
3) CMR
4) Follow-up and End Points: Patient follow-up was performed every 6 months after enrolment until the end of the study by trained physicians.
They performed office visits and ECG-Holter monitoring in all patients.
ICD analysis was performed in patients receiving the device.
If a patient missed the follow-up visit,
telephone contact,
review of out-patient clinic or hospital records and contact with patient primary care physician or cardiologist were carried out.
During follow-up,
we recorded the following end points as previously described (16): a) ventricular tachycardia; b) aborted SCD,
defined as an appropriate ICD intervention for ventricular arrhythmias; c) SCD defined as unexpected death either within 1 hour of cardiac symptom onset in the absence of progressive deterioration,
during sleep,
or within 24 hours of last being seen alive; e) chronic heart failure death,
defined as death associated with unstable or progressive deterioration of LV function despite active therapy.
Major adverse cardiac events (MACE) were defined as a composite end point of ventricular tachycardia,
aborted SCD or SCD.
Statistical analysis
Statistical analysis was performed with the SPSS,
version 17.0 software (SPSS Inc.,
Chicago,
IL).
Continuous variables are expressed as mean + SD and discrete variables as absolute numbers and percentages.The Spearman correlation and Bland-Altman analysis were used for comparing CMR to TTE values.
Student’s independent t- or Mann-Whitney tests were used as appropriate to compare continuous variables between patients with and without MACE.
Comparisons between groups of discrete variables were performed by Chi-square or Fisher’s exact test if the expected cell count was <5.
Univariate Cox proportional hazard models were used to assess the association between baseline covariates and the composite end point (results presented as hazard ratio and 95% confidence interval).
Variables with p<0.05 at univariate analysis were then included as covariates in multivariate Cox proportional hazard models to test which variables were independently associated with the composite end point.
Survival curves were obtained by Kaplan-Meier analysis and compared by log-rank test.
CMR-LVEF and presence of LGE were introduced in two separated models.
For each model,
the incremental value of predicting the composite end point by stepwise inclusion of CMR parameters in addition to clinical history and TTE parameters was assessed by the C2.
using Omnibus test of model coefficients.
Re-classification of patients was determined using net reclassification improvement (NRI) analysis for MACE and obtained by adding CMR-LVEF and LGE status to the model based on clinical history and TTE-LVEF.
All tests were 2-tailed,
and p<0.05 was considered statistically significant.