Remote past left ventricular function before chronic right ventricular pacing predicts responses to cardiac resynchronization therapy upgrade.

BACKGROUND: This study examined factors that could predict response to cardiac resynchronization therapy (CRT) upgrade in patients who developed heart failure (HF) after long-term right ventricular (RV) pacing.

METHODS: Twenty-five consecutive patients who received CRT upgrade for long-term RV pacing (RVP) were enrolled in this study. None of these patients were eligible for CRT at the moment of starting RVP. After 5.7 ± 4.0 years chronic RVP, these 25 patients developed HF symptoms and received CRT upgrade. Echocardiography was conducted at the moment of CRT upgrade and 6 months after CRT. Remote past left ventricular ejection fraction (RP-LVEF) at the moment of starting RVP was retrospectively obtained from the echocardiographic and cardiac catherization reports. Responders were defined as a reduction in LV end-systolic volume (LVESV) ≥ 15%. Their clinical and echocardiographic parameters were analyzed and compared.

RESULTS: Responders had significant higher RP-LVEF as compared to nonresponders (53.6 ± 16.5% vs 31.4 ± 11.6%, P = 0.002). RP-LVEF correlated with reduction in LVESV after CRT upgrade (P < 0.001). RP-LVEF ≥ 43.5% as a cutoff value predicted response to CRT upgrade with an area under the receiver-operating curve of 0.87, a sensitivity of 78%, and a specificity of 100%. Intrinsic QRS width, septal-posterior wall motion delay, or tissue Doppler-derived dyssynchrony indexes did not predict responses to CRT upgrade.

CONCLUSION: In long-term RVP patients who developed HF and received CRT upgrade, RP-LVEF ≥ 43.5% predicts good response. Conventional dyssynchrony indexes do not predict responses to CRT upgrade in these patients.