Low-dose dobutamine stress echo to quantify the degree of remodelling after cardiac resynchronization therapy.

AIMS: Presence of contractile reserve during low-dose dobutamine stress echo (DSE) appears predictive of cardiac resynchronization therapy (CRT) outcome. We hypothesize that changes in left bundle branch block (LBBB)-induced dyssynchronous motion during low-dose DSE could be related to the extent of reverse remodelling. METHODS AND RESULTS: Fifty-two patients (69 +/- 2 years, EF: 24 +/- 7%, QRS > 120 ms) were studied pre- and post-CRT (7 +/- 1 months). Reduction in left ventricular end-systolic volume (LVESV) >/=10% defined response. A clinical improvement was sought additionally prior to implant and after CRT (NYHA class reduction >1), increase in 6 min walk test (>10%), and fall in BNP (>/=30%). To identify the presence of septal scar and its impact on our assessment during low-dose DSE, a cardiac magnetic resonance was performed pre-CRT. Presence of an abnormal short-lived septal motion occurring during the isovolumic contraction time [septal flash (SF)] identified LBBB-induced dyssynchrony. Septal flash extent was quantified from M-mode and radial velocity traces. At baseline, 31/52 patients had an SF. In all patients, DSE increased SF. Twenty-nine out of thirty-one patients responded with reverse remodelling post-CRT. The degree of peak low-dose stress SF correlated with the extent of reverse remodelling (R = 0.6, P < 0.0001). Additionally, SF increase correlated with greater fall in BNP post-CRT (R = 0.4, P = 0.01). Among patients with no SF at rest (21/52 patients), low-dose DSE induced an SF and a fall in stroke volume (SV) in five patients who all showed reverse remodelling after CRT. With low-dose DSE, the remaining 16 patients all failed to demonstrate a SF, and all but one patient with additional atrioventricular dyssynchrony were non-responders. CONCLUSION: Low-dose DSE increases and unmasks LBBB-induced dyssynchronous motion, easing its detection. The degree of clinical and echocardiographic response correlated with the extent of peak SF seen during low-dose DSE.

Usefulness of changes in left ventricular wall thickness to predict full or partial pressure reperfusion in ST-elevation acute myocardial infarction.

Experimental studies have shown that if an acute transmural myocardial infarction is reperfused at full pressure there is an immediate and persisting increase in end-diastolic wall thickness (EDWT) due to massive intramural edema, with the amount of edema inversely related to the residual stenosis in the infarct-related artery. This study investigated if these findings are paralleled in the clinical setting and whether the resultant myocardial substrate differs after percutaneous coronary intervention (PCI) versus thrombolysis (the latter having a higher incidence of residual flow limiting stenosis in the culprit vessel). Eighty-eight consecutive patients with ST-elevation myocardial infarction were enrolled. Twenty-seven patients underwent primary PCI, 23 had rescue PCI, and 38 had thrombolysis. Standard M-mode and 2-dimensional echocardiographies were performed within 12 hours. Regional EDWT was measured in 904 infarct-related segments after the different reperfusion strategies and compared with 504 remote noninfarcted segments. EDWT of infarct-related segments after primary PCI was significantly increased compared with normal segments. At follow-up, after 6 months, EDWT of these segments was significantly decreased, indicating transmural infarction. EDWT of infarct-related segments after thrombolysis did not differ from that of normal segments. After rescue PCI, EDWT of infarct-related segments was significantly decreased compared with that of normal segments. In conclusion, full-pressure restoration of epicardial blood flow after transmural myocardial infarction causes an immediate increase in EDWT, easily detected by echocardiography. In contrast, pressure-limiting reperfusion (typical for thrombolysis) resultsin normal EDWT. This confirms experimental data that PCI and thrombolysis can differ in their resultant myocardial substrate.

The reno-protective effect of hydration with sodium bicarbonate plus N-acetylcysteine in patients undergoing emergency percutaneous coronary intervention: the RENO Study.

OBJECTIVES: This study was designed to determine the effectiveness of a protocol for rapid intravenous hydration to prevent contrast-induced nephropathy (CIN) in patients undergoing emergency percutaneous coronary intervention (PCI). BACKGROUND: Contrast-induced nephropathy frequently complicates PCI, resulting in prolonged hospitalization and increased in-hospital and long-term morbidity and mortality. Little is known regarding prevention of CIN in patients undergoing urgent PCI. METHODS: We conducted a prospective, controlled, randomized, single-center trial in 111 consecutive patients with acute coronary syndrome undergoing emergency PCI. As part of the hydration therapy, 56 patients (group A) received an infusion of sodium bicarbonate plus N-acetylcysteine (N-AC) started just before contrast injection and continued for 12 h after PCI. The remaining 55 patients (group B) received the standard hydration protocol consisting of intravenous isotonic saline for 12 h after PCI. In both groups, 2 doses of oral N-AC were administered the next day. RESULTS: The 2 groups were similar with respect to age, gender, diabetes mellitus, and baseline serum creatinine. A serum creatinine concentration >0.5 mg/dl from baseline after emergency PCI was observed in 1 patient in group A (1.8%) and in 12 patients in group B (21.8%; p < 0.001). Acute anuric renal failure was observed in 1 patient (1.8%) in group A and in 7 patients (12.7%) in group B (p = 0.032). CONCLUSIONS: Rapid intravenous hydration with sodium bicarbonate plus N-AC before contrast injection is effective and safe in the prevention of CIN in patients undergoing emergency PCI.