Impact of age on the prognosis of patients with ventricular tachyarrhythmias and aborted cardiac arrest

The present study is derived from an analysis of the Registry of Malignant Arrhythmias and Sudden Cardiac Death—Influence of Diagnostics and Interventions (RACE-IT) and presents a single-center registry of consecutive patients presenting to the UMM between 2002 and 2016 with VTA and SCD (clinicaltrials.gov identifier: NCT02982473; date of registration 5 December 2016) as previously published [6, 7] (suppl. Fig. 1, flowchart). The registry was established according to the principles of the Declaration of Helsinki and was approved by the Ethics Committee II of the Faculty of Medicine Mannheim, University of Heidelberg, Germany. VTA was defined according to current guidelines as previously published [2, 7].

Risk in the present analysis was stratified according to age, with both age as a binary and age as a continuous variable. For analysis with age as a binary variable, middle-aged (40–60 years old) patients were compared to older patients (> 60 years old) [8]. Furthermore, patients > 75 years were compared to patients < 75 years. Patients younger than 40 years old were excluded.

The primary endpoint was all-cause mortality at long-term follow-up of 2.5 years. The secondary endpoints were cardiac death at 24 h, all-cause mortality at index hospitalization, all-cause mortality after index hospitalization and the composite endpoint at 2.5 years of cardiac death at 24 h, recurrent VTA and appropriate ICD treatment.

As previously published, the statistical methods included multivariate Cox regression models, Kaplan-Meier analyses, and propensity score matching [7].

The present study included a total of 2259 consecutive patients presenting with VTA and aborted cardiac arrest. Of these, 28% were middle-aged (40–60 years old) and 72% were older (> 60 years old) (suppl. Fig. 1, flowchart). As outlined in Table 1, older patients showed higher rates of VT and middle-aged patients showed higher rates of VF. Middle-aged patients had higher rates of CPR due mainly to out-of-hospital CPR. Older patients suffered more often from arterial hypertension, diabetes mellitus and hyperlipidemia, whereas middle-aged patients showed higher rates of a family history of cardiac diseases and smoking. Prior CAD and prior myocardial infarction were more common in older patients; however, middle-aged patients had higher rates of acute myocardial infarction, coronary angiography and electrophysiological examination at index. Nonischemic cardiomyopathy was more frequent among the middle-aged and atrial fibrillation was more frequent among the older patients, besides CKD and chronic obstructive pulmonary disease (COPD). Older patients showed higher rates of prior heart failure, acute heart failure at index and highly restricted LVEF < 35%. Furthermore, older patients had higher rates of device treatment and they were more likely to take beta blockers, ACE inhibitors, angiotensin receptor blockers, statins, amiodarone and digitalis. Study population after propensity score matching is shown in suppl. Table 4.

As shown in Table 2, left panel, older patients > 60 years old in the unmatched cohort showed higher rates of all-cause mortality at 2.5 years (27% vs. 50%, p = 0.001, hazard ratio, HR = 2.137, 95% confidence interval, CI 1.809–2.523, p = 0.001), cardiac death at 24 h and all-cause mortality at index hospitalization and after index hospitalization. Furthermore, older patients showed higher rates of the composite endpoint at 2.5 years (24% vs. 34%, p = 0.001, HR = 1.471; 95% CI 1.230–1.759, p = 0.001). Even after propensity score matching, older patients showed increased mortality at 2.5 years, as shown in Table 2, right panel.

Age was significantly associated with the primary endpoint all-cause mortality at 2.5 years. Other predictors of this endpoint were CKD, LVEF < 35%, cardiogenic shock, CPR and male gender. The presence of an ICD and AMI were beneficial. (Table 3, upper panel). Age > 60 years was also significantly associated with the composite endpoint at 2.5 years. Other predictors of this endpoint were cardiogenic shock, ICD, LVEF < 35%, CPR and CKD; however, STEMI was not significantly associated with this endpoint (Table 3, lower panel). Furthermore, patient age as a continuous variable was independently associated with mortality at 2.5 years in all types of VTA (suppl. Tables 1–3).

As shown in Fig. 1, older patients > 60 years had a worse long-term prognosis for all-cause mortality (18% vs. 35%, p = 0.001, HR = 2.023; 95% CI 1.550–2.641, p = 0.001) and the composite endpoint at 2.5 years (18% vs. 25%, p = 0.006, HR = 1.401; 95% CI 1.050–1.870, p = 0.020). Furthermore, patients ≥ 75 years were associated with increased mortality at 2.5 years and an increased risk of the composite endpoint (suppl. Fig. 2).

The multivariate Cox regression model values in Table 4 show consistent significant associations of CKD, LVEF < 35% and CPR with all-cause mortality at 2.5 years and the composite endpoint at 2.5 years for both middle-aged (40–60 years old) and older patients > 60 years old. In contrast, STEMI and ICD at index were beneficial. There was an association among middle-aged patients after cardiogenic shock and ICD treatment with all-cause mortality at 2.5 years, despite a lack of association with the composite endpoint.